MUST READ if you have fuel sender/p2068 issues
02-23-2014, 06:50 PM
#1
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MUST READ if you have fuel sender/p2068 issues
...or How to Stop all the Dings, DIC Messages and glowing MIL Lamp for 3 bucks and an hour of your time.
First a disclaimer: Use the following information for your possible benefit AND at your risk. I am not an electrical engineer. But I think some will be happy with the results I got with this “experiment.”
A while back I started a thread asking if there was a way to trick the right tank fuel sender so the error codes would stop.
http://forums.corvetteforum.com/c6-c...el-sender.html
The responses almost convinced me that it couldn’t be done. But even though I am quick to give up on ideas, I decided not to give up on my theory and delved into the service manual for information. From what I saw, it looked like the sender in the tank was just a simple potentiometer/rheostat. It looked like it didn’t have any factor in signaling the jet transfer pump to move fuel between tanks (see Venturi pump info below). The fact that when the sender circuit failed and the MIL lamp glowed and nothing else started acting up, I was mildly convinced that the only thing adversely affected by the bad sender was merely the display on the dash.
I decided that if I could GET to the wires that go to the fuel sender that I could cut them and wire in a new sender on the outside of the tank. Then I could just slide the float arm to “empty” for the secondary tank and the errors would stop. In other words, the ECM would always get an empty RH tank signal causing the gage to read no higher than half full and then gage fuel level would drop between half and empty because it was using data from the left tank sender.
Here is info from the service manual that I used when deciding if this was possible:
FUEL SENDER OPERATION
The fuel level sender changes resistance in response to the fuel level. The engine control module (ECM) monitors the signal circuit of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the primary and the secondary fuel level sender resistance is low and the ECM senses a low signal voltage. When the fuel tank is empty, the primary and the secondary fuel level sender resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the primary and secondary fuel level sender in order to calculate the percentage of remaining fuel in the tanks. The ECM sends the fuel level information via serial data circuit to the instrument panel cluster (IPC) for display in the fuel gage.
(The RH tank sender for 2007 and up should test to 247-253 Ohms from Half full to Empty and 38-41.5 Ohms at Full. 2005-06 are opposite of these readings.)
FUEL SYSTEM OPERATION
The fuel system is a returnless on-demand design. The fuel pressure regulator is a part of the fuel tank module, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.
Two fuel tanks store the fuel supply. An electric turbine style fuel pump attaches to the fuel tank module inside the left fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pump also supplies fuel to a Venturi pump located on the bottom of the left fuel tank module. The function of the Venturi pump is to fill the left fuel tank module reservoir. The primary fuel pressure regulator, a part of the left fuel tank module, maintains the correct fuel pressure to the fuel injection system. The left fuel tank module contains a reverse flow check valve. The check valve, the primary fuel pressure regulator, and the secondary fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.
The fuel pump also supplies a small amount of pressurized fuel through the auxiliary fuel feed pipe to the siphon jet pump inside the right fuel tank. The pressurized fuel creates a Venturi action inside the siphon jet pump. The Venturi action causes the fuel to be drawn out of the right fuel tank.
The fuel transfers from the right fuel tank to the left fuel tank through the auxiliary fuel return pipe. The auxiliary fuel return pipe inside the left fuel tank contains an anti-siphon hole in order to prevent fuel from siphoning from the left fuel tank into the right fuel tank. Both the auxiliary fuel feed pipe and the auxiliary fuel return pipe are located inside the convoluted stainless steel crossover hose.
The right fuel tank module contains a secondary fuel pressure regulator. The secondary fuel pressure regulator has a lower set point than the primary regulator in order to allow fuel to flow to the siphon jet pump on the right fuel tank module. When the engine is shut off, the pressure in the feed pipes immediately drops to the secondary regulator set point. This prevents the siphon jet pump from operating and in turn prevents the equalization of the left and right fuel tanks. The secondary fuel pressure regulator maintains fuel pressure in the auxiliary fuel feed pipe which reduces the time to prime the siphon jet pump. The pressurization also reduces fuel vaporization and boiling in the auxiliary fuel feed pipe.
So now I set out to see if I could get to the tank wires. Luckily I found a picture of the dual fuel tank setup that someone took as it sat on their driveway. I saw that the RH tank wires were routed to the right side toward the wheel. I pulled the wheel and the splash guard and right there it was….the tank plugs! There is a 6 pin in line plug on the frame and a 4 pin plug going into the tank module. This is the plug that has the 2 sender wires to modify.
After I ordered a new sender, I cancelled the order because I thought..why can’t I find a simple resistor to put in place of the sender rheostat (which is just a variable resistor)? I need a fixed 250 Ohms across the 2 wires to tell the ECM that the RH tank was empty. (40 Ohms for 05 and 06) I went to Radio Shack and found this:
http://www.radioshack.com/product/in...ductId=2062317
They don’t carry a 250 Ohm resistor, so in addition to this 220 Ohm resistor, I also bought their 33 Ohm ones. http://www.radioshack.com/product/in...ductId=2062312 When you connect a 220 and a 33, you get 253 Ohms of resistance. Close enough I hoped… but the 220 resistor happened to read 217 so I got a perfect 250 when I soldered them together. They come 5 to a pack so test several until you find 2 that add up to 250. Early model guys can probably find mutiple resistors to get to 40 if the Shack does not carry 40s. Even four 10s connected would get you there.
Below is a step-by-step on what I did to replace the bad in-tank sender with 2 resistors totaling 250 Ohms soldered to the outside plug wires. The upside to this setup is that the dinging and MIL light goes away for only $3 instead of $1200. The downside is that the gas gage will show no more than half a tank. I can live with that because I am more concerned with when the tank is 1/4 full or less and a refill is due. The left sender will still function and display this. If you can live with that it might be worth the hour or two of your time. Oh…and 3 bucks.
STEPS TO DISCONNECT THE DEFECTIVE RIGHT TANK FUEL SENDER AND ADD A RESISTOR THAT TRICKS THE ECM AND STOPS THE TROUBLE CODES:
1) Attach a 220 and 33 ohm resistor together by twisting the wires and soldering together. Verify with a VOM that it is about 250 ohms of resistance. If your VOM reads in k-Ohms, you are looking for .250 on the display.
2) Pull right wheel, remove 7mm screw holding the brake cooling duct to frame, remove 2 plastic rivets holding the flexible splash shield on. It can now swing out of the way. Pull the in-line harness clip off the frame if you need more room to get to the plug on top of the tank. Do not cut into this in-line harness to add the resistor because the LOW REFERENCE wire at that plug is shared with tank pressure sensor and cutting here would kill that circuit.
3) Instead, pull the square plug behind it. Do this by sliding the red lock out and pressing down to unlock while pulling off. This 4-pin plug has only 3 wires.
4) The plug harness is long enough to pull out of the frame to work on it. You will locate and cut the 2 wires that go to the fuel sender. I cut about 2 inches from the plug. The service manual connector end view diagram did not match my car (??) but the colors did. For my 07 there is a light blue signal wire and a black low reference wire. These are the 2. The black/white stripe wire is a ground and stays as is. I verified it was indeed the ground wire by verifying continuity to the metal chassis.
5) Connect and solder the 2 ends of the resistor leads to the 2 cut wires where they lead to the in-line plug. It doesn’t matter which direction or wire. The 2 cut wires coming out of the plug are left as is. Tape the bare wire areas to prevent shorts, BUT don’t tape over the resistors so they can better dissipate heat. Then plug the plug back in to the module. I took a picture of my rig up if someone wants me to send it to them so they can post it. I don’t have Photobucket set up.
6) I covered my ***** and said a quick prayer as I started the car hoping not to see a puff of smoke coming from the ECM. No codes set and gage worked as I hoped. If all is well, put the splash shield back together and hit the road with a smile on your face.
Worked for me...may work for you.
First a disclaimer: Use the following information for your possible benefit AND at your risk. I am not an electrical engineer. But I think some will be happy with the results I got with this “experiment.”
A while back I started a thread asking if there was a way to trick the right tank fuel sender so the error codes would stop.
http://forums.corvetteforum.com/c6-c...el-sender.html
The responses almost convinced me that it couldn’t be done. But even though I am quick to give up on ideas, I decided not to give up on my theory and delved into the service manual for information. From what I saw, it looked like the sender in the tank was just a simple potentiometer/rheostat. It looked like it didn’t have any factor in signaling the jet transfer pump to move fuel between tanks (see Venturi pump info below). The fact that when the sender circuit failed and the MIL lamp glowed and nothing else started acting up, I was mildly convinced that the only thing adversely affected by the bad sender was merely the display on the dash.
I decided that if I could GET to the wires that go to the fuel sender that I could cut them and wire in a new sender on the outside of the tank. Then I could just slide the float arm to “empty” for the secondary tank and the errors would stop. In other words, the ECM would always get an empty RH tank signal causing the gage to read no higher than half full and then gage fuel level would drop between half and empty because it was using data from the left tank sender.
Here is info from the service manual that I used when deciding if this was possible:
FUEL SENDER OPERATION
The fuel level sender changes resistance in response to the fuel level. The engine control module (ECM) monitors the signal circuit of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the primary and the secondary fuel level sender resistance is low and the ECM senses a low signal voltage. When the fuel tank is empty, the primary and the secondary fuel level sender resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the primary and secondary fuel level sender in order to calculate the percentage of remaining fuel in the tanks. The ECM sends the fuel level information via serial data circuit to the instrument panel cluster (IPC) for display in the fuel gage.
(The RH tank sender for 2007 and up should test to 247-253 Ohms from Half full to Empty and 38-41.5 Ohms at Full. 2005-06 are opposite of these readings.)
FUEL SYSTEM OPERATION
The fuel system is a returnless on-demand design. The fuel pressure regulator is a part of the fuel tank module, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.
Two fuel tanks store the fuel supply. An electric turbine style fuel pump attaches to the fuel tank module inside the left fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pump also supplies fuel to a Venturi pump located on the bottom of the left fuel tank module. The function of the Venturi pump is to fill the left fuel tank module reservoir. The primary fuel pressure regulator, a part of the left fuel tank module, maintains the correct fuel pressure to the fuel injection system. The left fuel tank module contains a reverse flow check valve. The check valve, the primary fuel pressure regulator, and the secondary fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.
The fuel pump also supplies a small amount of pressurized fuel through the auxiliary fuel feed pipe to the siphon jet pump inside the right fuel tank. The pressurized fuel creates a Venturi action inside the siphon jet pump. The Venturi action causes the fuel to be drawn out of the right fuel tank.
The fuel transfers from the right fuel tank to the left fuel tank through the auxiliary fuel return pipe. The auxiliary fuel return pipe inside the left fuel tank contains an anti-siphon hole in order to prevent fuel from siphoning from the left fuel tank into the right fuel tank. Both the auxiliary fuel feed pipe and the auxiliary fuel return pipe are located inside the convoluted stainless steel crossover hose.
The right fuel tank module contains a secondary fuel pressure regulator. The secondary fuel pressure regulator has a lower set point than the primary regulator in order to allow fuel to flow to the siphon jet pump on the right fuel tank module. When the engine is shut off, the pressure in the feed pipes immediately drops to the secondary regulator set point. This prevents the siphon jet pump from operating and in turn prevents the equalization of the left and right fuel tanks. The secondary fuel pressure regulator maintains fuel pressure in the auxiliary fuel feed pipe which reduces the time to prime the siphon jet pump. The pressurization also reduces fuel vaporization and boiling in the auxiliary fuel feed pipe.
So now I set out to see if I could get to the tank wires. Luckily I found a picture of the dual fuel tank setup that someone took as it sat on their driveway. I saw that the RH tank wires were routed to the right side toward the wheel. I pulled the wheel and the splash guard and right there it was….the tank plugs! There is a 6 pin in line plug on the frame and a 4 pin plug going into the tank module. This is the plug that has the 2 sender wires to modify.
After I ordered a new sender, I cancelled the order because I thought..why can’t I find a simple resistor to put in place of the sender rheostat (which is just a variable resistor)? I need a fixed 250 Ohms across the 2 wires to tell the ECM that the RH tank was empty. (40 Ohms for 05 and 06) I went to Radio Shack and found this:
http://www.radioshack.com/product/in...ductId=2062317
They don’t carry a 250 Ohm resistor, so in addition to this 220 Ohm resistor, I also bought their 33 Ohm ones. http://www.radioshack.com/product/in...ductId=2062312 When you connect a 220 and a 33, you get 253 Ohms of resistance. Close enough I hoped… but the 220 resistor happened to read 217 so I got a perfect 250 when I soldered them together. They come 5 to a pack so test several until you find 2 that add up to 250. Early model guys can probably find mutiple resistors to get to 40 if the Shack does not carry 40s. Even four 10s connected would get you there.
Below is a step-by-step on what I did to replace the bad in-tank sender with 2 resistors totaling 250 Ohms soldered to the outside plug wires. The upside to this setup is that the dinging and MIL light goes away for only $3 instead of $1200. The downside is that the gas gage will show no more than half a tank. I can live with that because I am more concerned with when the tank is 1/4 full or less and a refill is due. The left sender will still function and display this. If you can live with that it might be worth the hour or two of your time. Oh…and 3 bucks.
STEPS TO DISCONNECT THE DEFECTIVE RIGHT TANK FUEL SENDER AND ADD A RESISTOR THAT TRICKS THE ECM AND STOPS THE TROUBLE CODES:
1) Attach a 220 and 33 ohm resistor together by twisting the wires and soldering together. Verify with a VOM that it is about 250 ohms of resistance. If your VOM reads in k-Ohms, you are looking for .250 on the display.
2) Pull right wheel, remove 7mm screw holding the brake cooling duct to frame, remove 2 plastic rivets holding the flexible splash shield on. It can now swing out of the way. Pull the in-line harness clip off the frame if you need more room to get to the plug on top of the tank. Do not cut into this in-line harness to add the resistor because the LOW REFERENCE wire at that plug is shared with tank pressure sensor and cutting here would kill that circuit.
3) Instead, pull the square plug behind it. Do this by sliding the red lock out and pressing down to unlock while pulling off. This 4-pin plug has only 3 wires.
4) The plug harness is long enough to pull out of the frame to work on it. You will locate and cut the 2 wires that go to the fuel sender. I cut about 2 inches from the plug. The service manual connector end view diagram did not match my car (??) but the colors did. For my 07 there is a light blue signal wire and a black low reference wire. These are the 2. The black/white stripe wire is a ground and stays as is. I verified it was indeed the ground wire by verifying continuity to the metal chassis.
5) Connect and solder the 2 ends of the resistor leads to the 2 cut wires where they lead to the in-line plug. It doesn’t matter which direction or wire. The 2 cut wires coming out of the plug are left as is. Tape the bare wire areas to prevent shorts, BUT don’t tape over the resistors so they can better dissipate heat. Then plug the plug back in to the module. I took a picture of my rig up if someone wants me to send it to them so they can post it. I don’t have Photobucket set up.
6) I covered my ***** and said a quick prayer as I started the car hoping not to see a puff of smoke coming from the ECM. No codes set and gage worked as I hoped. If all is well, put the splash shield back together and hit the road with a smile on your face.
Worked for me...may work for you.
02-25-2014, 07:10 AM
#3
Safety Car
Mine is doing the same thing, but I'm still under warranty, it goes away after using about 1/2 gallon of gas (about 10 -15 miles of driving). I'm gonna live with mine for now.
And, when I schedule my repairs, and they drop my tanks, I'm going to get them to put in a Z06 fuel pump (at my cost), so that I'm prepped for a supercharger fuel supply, if I decide to put one on the LS3 later.
And, when I schedule my repairs, and they drop my tanks, I'm going to get them to put in a Z06 fuel pump (at my cost), so that I'm prepped for a supercharger fuel supply, if I decide to put one on the LS3 later.
02-27-2014, 06:59 AM
#5
Safety Car
03-12-2014, 01:29 PM
#8
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I will get it to empty on a long trip this weekend and will update on how it acts as i get down to a couple of gallons.
03-19-2014, 04:35 PM
#9
Melting Slicks
so you think the right tank is the first half tank, and the left tank is second half on the empty side of the gauge. like the computer adds the two signals together vs. an average.
03-19-2014, 08:13 PM
#10
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This weekend as I emptied the tanks I discovered another diagnostic that the ECM computes. If you drive more than 60 miles with no change in the fuel level readings, you get a "service fuel system" ding and a pending code of P0461.
Circuit/System Description
The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are low and the ECM senses a low signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are high and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data circuit to the instrument cluster in order to control the fuel gage.
Conditions for Setting the DTC
• The ECM detects that the primary fuel tank is greater than 28.5 L (7.5 gal) and the secondary fuel tank is less than 3.3 L (.87 gal) over a distance of 200 km (124.2 mi).
• The ECM detects that the primary fuel tank is less than 28.5 L (7.5 gal) and no change in primary tank of at least 3 L (.79 gal) over a distance of 80 km (49.7 mi).
and P2066
Circuit/System Description
The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are low and the ECM senses a low signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are high and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data circuit to the instrument cluster in order to control the fuel gage.
Conditions for Setting the DTC
P2066
• The secondary fuel tank is equal to or greater than 3.3 L (.87 gal) and the ECM does not detect a change in the secondary fuel level of at least 3 L (0.79 gal) over a distance of 100 km (62 mi).
• The ECM detects that the primary fuel tank is less than 28.5 L (7.5 gal) and the secondary fuel tank is more than 3.3 L (.87 gal) and the condition is present for 30 minutes.
• The ECM detects that the primary fuel tank is greater than 28.5 L (7.5 gal) and the secondary fuel tank is less than 3.3 L (.87 gal) over a distance of 200 km (124.2 mi).
To try to prevent this from popping up, I have added a toggle that changes the resistance between 250 ohms and a lower value. This way the ECM won't see the same reading over many miles causing the DTC to appear. Haven't fully tested it yet.
03-19-2014, 09:53 PM
#11
Racer
Mine is doing the same thing, but I'm still under warranty, it goes away after using about 1/2 gallon of gas (about 10 -15 miles of driving). I'm gonna live with mine for now.
And, when I schedule my repairs, and they drop my tanks, I'm going to get them to put in a Z06 fuel pump (at my cost), so that I'm prepped for a supercharger fuel supply, if I decide to put one on the LS3 later.
And, when I schedule my repairs, and they drop my tanks, I'm going to get them to put in a Z06 fuel pump (at my cost), so that I'm prepped for a supercharger fuel supply, if I decide to put one on the LS3 later.
02-10-2015, 12:37 AM
#12
Melting Slicks
There is no averaging. Each tank's senders send signals to the ecm. When the right tank is empty it reads 250 ohms resistance ('07 and later). Then as the left tank level drops, the resistance level changes and the gage on the dash drops.
This weekend as I emptied the tanks I discovered another diagnostic that the ECM computes. If you drive more than 60 miles with no change in the fuel level readings, you get a "service fuel system" ding and a pending code of P0461.
Circuit/System Description
The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are low and the ECM senses a low signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are high and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data circuit to the instrument cluster in order to control the fuel gage.
Conditions for Setting the DTC
• The ECM detects that the primary fuel tank is greater than 28.5 L (7.5 gal) and the secondary fuel tank is less than 3.3 L (.87 gal) over a distance of 200 km (124.2 mi).
• The ECM detects that the primary fuel tank is less than 28.5 L (7.5 gal) and no change in primary tank of at least 3 L (.79 gal) over a distance of 80 km (49.7 mi).
and P2066
Circuit/System Description
The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are low and the ECM senses a low signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are high and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data circuit to the instrument cluster in order to control the fuel gage.
Conditions for Setting the DTC
P2066
• The secondary fuel tank is equal to or greater than 3.3 L (.87 gal) and the ECM does not detect a change in the secondary fuel level of at least 3 L (0.79 gal) over a distance of 100 km (62 mi).
• The ECM detects that the primary fuel tank is less than 28.5 L (7.5 gal) and the secondary fuel tank is more than 3.3 L (.87 gal) and the condition is present for 30 minutes.
• The ECM detects that the primary fuel tank is greater than 28.5 L (7.5 gal) and the secondary fuel tank is less than 3.3 L (.87 gal) over a distance of 200 km (124.2 mi).
To try to prevent this from popping up, I have added a toggle that changes the resistance between 250 ohms and a lower value. This way the ECM won't see the same reading over many miles causing the DTC to appear. Haven't fully tested it yet.
This weekend as I emptied the tanks I discovered another diagnostic that the ECM computes. If you drive more than 60 miles with no change in the fuel level readings, you get a "service fuel system" ding and a pending code of P0461.
Circuit/System Description
The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are low and the ECM senses a low signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are high and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data circuit to the instrument cluster in order to control the fuel gage.
Conditions for Setting the DTC
• The ECM detects that the primary fuel tank is greater than 28.5 L (7.5 gal) and the secondary fuel tank is less than 3.3 L (.87 gal) over a distance of 200 km (124.2 mi).
• The ECM detects that the primary fuel tank is less than 28.5 L (7.5 gal) and no change in primary tank of at least 3 L (.79 gal) over a distance of 80 km (49.7 mi).
and P2066
Circuit/System Description
The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistances of both fuel level senders are low and the ECM senses a low signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are high and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data circuit to the instrument cluster in order to control the fuel gage.
Conditions for Setting the DTC
P2066
• The secondary fuel tank is equal to or greater than 3.3 L (.87 gal) and the ECM does not detect a change in the secondary fuel level of at least 3 L (0.79 gal) over a distance of 100 km (62 mi).
• The ECM detects that the primary fuel tank is less than 28.5 L (7.5 gal) and the secondary fuel tank is more than 3.3 L (.87 gal) and the condition is present for 30 minutes.
• The ECM detects that the primary fuel tank is greater than 28.5 L (7.5 gal) and the secondary fuel tank is less than 3.3 L (.87 gal) over a distance of 200 km (124.2 mi).
To try to prevent this from popping up, I have added a toggle that changes the resistance between 250 ohms and a lower value. This way the ECM won't see the same reading over many miles causing the DTC to appear. Haven't fully tested it yet.
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02-10-2015, 04:19 AM
#13
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Yes. I have a small box with a toggle that switches between the 2 resistance values (40 and 250 I think). When "service fuel system" pops up, I toggle over. Makes the fuel gage move and stops message.
The only problem is on long trips when the engine does not get shut off. Sometimes it throws a check engine light that has to be cleared. Still better than constant dings or $1500 repair.
The only problem is on long trips when the engine does not get shut off. Sometimes it throws a check engine light that has to be cleared. Still better than constant dings or $1500 repair.
02-10-2015, 03:04 PM
#14
Drifting
I had the same problem and my gas gauge stopped working. I did the Techron additive and thankfully the gauge started working again. I have been filling up with Chevron since and no more issues. I was going to drop the tanks and change the sender but thankfully, this worked...
02-10-2015, 07:00 PM
#15
Team Owner
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I don't leave near an urban area, and the only top tier nearby is Mobil, which is what I use.
Should I use Techron anyway once in a while? What, every 1,000 miles or something?
Should I use Techron anyway once in a while? What, every 1,000 miles or something?
02-10-2015, 11:49 PM
#16
Melting Slicks
My car has just developed this issue under certain conditions. The last two times my level has gone down to 1/3 of a tank, I've gotten the warning chime and “Service fuel system “message along with the gauge going to zero.
I’ve added a bottle of Lucas Deep Fuel System Cleaner each of the last two fill ups, but I still have the issue. I ran for a couple of weeks after the first instance and did not let the level drop below half a tank, and no issues. Last tankful, I decided to let the level go down, and right at 1/3 the problem is triggered. I can clear the code, and all’s well, at least until I hit 1/3 of a tank. I’ll keep trying fuel cleaners for a while and see how it goes.
BTW, for the past 3+ years I have used Chevron 94 octane exclusively, nothing else. I recall reading a post on this board years back by a retired petroleum engineer, who suggested the best strategy for keeping the fuel system clean was to change among the top tier brands every 6 months, since each has slight differences in the formulation of their additives, and each will be a little better than the others at cleaning certain types of build-up. I think I’m going to give that a try, switch to Shell for 6 months, certainly can’t hurt.
I’ve added a bottle of Lucas Deep Fuel System Cleaner each of the last two fill ups, but I still have the issue. I ran for a couple of weeks after the first instance and did not let the level drop below half a tank, and no issues. Last tankful, I decided to let the level go down, and right at 1/3 the problem is triggered. I can clear the code, and all’s well, at least until I hit 1/3 of a tank. I’ll keep trying fuel cleaners for a while and see how it goes.
BTW, for the past 3+ years I have used Chevron 94 octane exclusively, nothing else. I recall reading a post on this board years back by a retired petroleum engineer, who suggested the best strategy for keeping the fuel system clean was to change among the top tier brands every 6 months, since each has slight differences in the formulation of their additives, and each will be a little better than the others at cleaning certain types of build-up. I think I’m going to give that a try, switch to Shell for 6 months, certainly can’t hurt.
02-16-2015, 12:43 AM
#17
Droping fuel tanks
My car has just developed this issue under certain conditions. The last two times my level has gone down to 1/3 of a tank, I've gotten the warning chime and “Service fuel system “message along with the gauge going to zero.
I’ve added a bottle of Lucas Deep Fuel System Cleaner each of the last two fill ups, but I still have the issue. I ran for a couple of weeks after the first instance and did not let the level drop below half a tank, and no issues. Last tankful, I decided to let the level go down, and right at 1/3 the problem is triggered. I can clear the code, and all’s well, at least until I hit 1/3 of a tank. I’ll keep trying fuel cleaners for a while and see how it goes.
BTW, for the past 3+ years I have used Chevron 94 octane exclusively, nothing else. I recall reading a post on this board years back by a retired petroleum engineer, who suggested the best strategy for keeping the fuel system clean was to change among the top tier brands every 6 months, since each has slight differences in the formulation of their additives, and each will be a little better than the others at cleaning certain types of build-up. I think I’m going to give that a try, switch to Shell for 6 months, certainly can’t hurt.
I’ve added a bottle of Lucas Deep Fuel System Cleaner each of the last two fill ups, but I still have the issue. I ran for a couple of weeks after the first instance and did not let the level drop below half a tank, and no issues. Last tankful, I decided to let the level go down, and right at 1/3 the problem is triggered. I can clear the code, and all’s well, at least until I hit 1/3 of a tank. I’ll keep trying fuel cleaners for a while and see how it goes.
BTW, for the past 3+ years I have used Chevron 94 octane exclusively, nothing else. I recall reading a post on this board years back by a retired petroleum engineer, who suggested the best strategy for keeping the fuel system clean was to change among the top tier brands every 6 months, since each has slight differences in the formulation of their additives, and each will be a little better than the others at cleaning certain types of build-up. I think I’m going to give that a try, switch to Shell for 6 months, certainly can’t hurt.
04-23-2015, 07:42 PM
#18
1st Gear
Member Since: Apr 2015
Posts: 1
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Bought me 2 years to replace fuel sender
This worked great on my 07 C6. I passed CA emissions, so I have 2 years to drop the passenger gas tank and replace the sender unit. I did not cut the wires. I made an extension wire using RS crimp on quick connects to maintain the black/white wire circuit. Plug the male end into the connector, the female end into the pump receptor. I then made a "U" out of the resistors and plugged them into the two connector ports. Seal the receptor and connector with high quality electrical tape, stuff back into the space above the tank, and reinstall the access panel and wheel well cover.
I already purchased the new sender unit and pump. I may place the sender unit in the cabin and run two wires back to the connector ports, after removing the resistors workaround. That way I can just manually move the sender unit to match gallons used.
$2,500 vs $3 at RS, thanks again.
I already purchased the new sender unit and pump. I may place the sender unit in the cabin and run two wires back to the connector ports, after removing the resistors workaround. That way I can just manually move the sender unit to match gallons used.
$2,500 vs $3 at RS, thanks again.
11-27-2015, 06:23 AM
#20