Issue after Fuel Pump Replacement
10-01-2017, 06:59 PM
#1
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Issue after Fuel Pump Replacement
Greetings fellow Vett enthusiasts,
Several months ago the fuel gauge in my 2006 Z51 Automatic started acting up. I was on a long road trip when it first threw me for a loop, I thought I was doing a good job of keeping an eye out on the fuel level when out of the blue the low fuel warning chime caught my attention. I was baffled, I thought I had just under a half tank of fuel left. I figured I must have zoned out as the miles passed. After filling the tank (it only accepted about 10 gallons at the pump) I was rather confused. Sure that the tank capacity was 18 gallons, meaning I still must have had 8 gallons on hand but the gauge had read empty. From then the problem manifested itself more and more frequently.
After searching the forums for answers, I became more certain that the sending unit was starting to go bad ( there are of course two units, one in each tank). From what I could tell, folks had been able to pull out the swap at home, but all the accounts I read were for manual transmission models, so I did not have a ton of confidence in attempting the job. Regardless after getting a quote for the job of nearly $2000, I decided to buy the parts (about $300 for the pump and a new sending unit for the right side) and attempt the job myself.
So this past Saturday I got the tools out and went to work at about 8 am. I started off by driving the front wheels onto ramps and then jacked up the rear end (not before breaking the lug nuts loose on the back wheels). I placed jack stands and removed the back wheels, pulled the wheel-wells, and removed the fuel tank access hatch on the right side wheel well (right=passenger side). From here I disconnected the "evap" lines from the passenger tank and the wires. Got under the car and removed the aluminum plates under each tank, they were bolted in with 5x bolts each, 15mm if I recall. at this point while laying under the car looking up I could see the cross-over tube, but the exhaust pipes were in the way and stopped my from getting my hands up to loosen the cross-over tube. So I removed the "H" pipe from the exhaust, sadly I am getting rather good at this procedure haha. Once this was out of the way I was able to get my hands where they needed to be, although it still took like another two hours of feeling around to get the cross-over pipe unhooked from the passenger side tank. Once that major achievement was finished I was able to drop the tank and slide it out from under the car (note this tank was empty as it drains first, then the driver side drains while driving).
After another good little while I got the old sending unit out and installed a new one. While I had the pressure relieved on the cross-over tube I went about dropping the driver side tank, it took another good hour to get the cross-over tube removed, the space is so tight, I can really see why a normal shop would rather drop the transmission. Long story short, I was able to get the new fuel pump installed, put the tanks back in their place. It only took me about 11 hours to get this far, haha (and counting, the wheels were still off at this point as well as the wheel wells, I did have the H pipe reinstalled). So the moment of truth, I reconnected the battery, and tried to start the car ( there were about 4 gallons of fuel in the tank at this point). I held down the start button for about 5 seconds, the starter turned the engine over but no luck.
On the second attempt (after the fuel system was re-pressurized) the engine came to life after about two seconds of holding down the start button. Success! At this point in time the fuel gauge read about 1/4 full. I turned the car off and restarted, it roared to life! I turned it off and got to work reinstalling the wheel wells, tires and lowered the car. at this point I re-added some fuel from a gas can that I had used to lower the fuel level in the tank prior to starting the project to make the tank driver side tank lighter to handlle, I had 2x 2 gallon cans that I added back to the tank (4 gallons total). Here's where things got weird, After getting back in the car and starting it up, the gas gauge now showed the needle on empty (no warnings or chimes though). I thought this was really odd and decided to drive to the local gas station and top off. After filing the tank (it accepted about 10 gallons) and starting the car, the gauge now read half full. Very strange. I decided to call it a night.
The next day, (today) I decided to put some miles on the car and see if the needle would move, and sure enough after about 25 mile the needle was now just a little below half a tank. This is super weird because it seems to me like this confirms that the passenger side sending unit is now functioning normally, bur for some reason the driver side unit must be sending an empty signal? But if this is the case why did it show a quarter tank when I first turned the car on after installing the new pump and sensors? And what caused the needle to drop to zero after I added back in those 4 gallons I had on hand? My plan moving forward is to wait and see what happens. I have already tried disconnecting the battery and reconnecting it to see if that reset the computer, no luck. So the moral of this story is twofold, yes one can replace a fuel pump and sending unit on an automatic C6 at home, and it can easily take all day if it is the first time you are attempting it. The second point to ask if anyone else has experienced anything similar after replacing a sending unit and how did you go about getting the gauge to read correctly? Thanks and happy driving!
Several months ago the fuel gauge in my 2006 Z51 Automatic started acting up. I was on a long road trip when it first threw me for a loop, I thought I was doing a good job of keeping an eye out on the fuel level when out of the blue the low fuel warning chime caught my attention. I was baffled, I thought I had just under a half tank of fuel left. I figured I must have zoned out as the miles passed. After filling the tank (it only accepted about 10 gallons at the pump) I was rather confused. Sure that the tank capacity was 18 gallons, meaning I still must have had 8 gallons on hand but the gauge had read empty. From then the problem manifested itself more and more frequently.
After searching the forums for answers, I became more certain that the sending unit was starting to go bad ( there are of course two units, one in each tank). From what I could tell, folks had been able to pull out the swap at home, but all the accounts I read were for manual transmission models, so I did not have a ton of confidence in attempting the job. Regardless after getting a quote for the job of nearly $2000, I decided to buy the parts (about $300 for the pump and a new sending unit for the right side) and attempt the job myself.
So this past Saturday I got the tools out and went to work at about 8 am. I started off by driving the front wheels onto ramps and then jacked up the rear end (not before breaking the lug nuts loose on the back wheels). I placed jack stands and removed the back wheels, pulled the wheel-wells, and removed the fuel tank access hatch on the right side wheel well (right=passenger side). From here I disconnected the "evap" lines from the passenger tank and the wires. Got under the car and removed the aluminum plates under each tank, they were bolted in with 5x bolts each, 15mm if I recall. at this point while laying under the car looking up I could see the cross-over tube, but the exhaust pipes were in the way and stopped my from getting my hands up to loosen the cross-over tube. So I removed the "H" pipe from the exhaust, sadly I am getting rather good at this procedure haha. Once this was out of the way I was able to get my hands where they needed to be, although it still took like another two hours of feeling around to get the cross-over pipe unhooked from the passenger side tank. Once that major achievement was finished I was able to drop the tank and slide it out from under the car (note this tank was empty as it drains first, then the driver side drains while driving).
After another good little while I got the old sending unit out and installed a new one. While I had the pressure relieved on the cross-over tube I went about dropping the driver side tank, it took another good hour to get the cross-over tube removed, the space is so tight, I can really see why a normal shop would rather drop the transmission. Long story short, I was able to get the new fuel pump installed, put the tanks back in their place. It only took me about 11 hours to get this far, haha (and counting, the wheels were still off at this point as well as the wheel wells, I did have the H pipe reinstalled). So the moment of truth, I reconnected the battery, and tried to start the car ( there were about 4 gallons of fuel in the tank at this point). I held down the start button for about 5 seconds, the starter turned the engine over but no luck.
On the second attempt (after the fuel system was re-pressurized) the engine came to life after about two seconds of holding down the start button. Success! At this point in time the fuel gauge read about 1/4 full. I turned the car off and restarted, it roared to life! I turned it off and got to work reinstalling the wheel wells, tires and lowered the car. at this point I re-added some fuel from a gas can that I had used to lower the fuel level in the tank prior to starting the project to make the tank driver side tank lighter to handlle, I had 2x 2 gallon cans that I added back to the tank (4 gallons total). Here's where things got weird, After getting back in the car and starting it up, the gas gauge now showed the needle on empty (no warnings or chimes though). I thought this was really odd and decided to drive to the local gas station and top off. After filing the tank (it accepted about 10 gallons) and starting the car, the gauge now read half full. Very strange. I decided to call it a night.
The next day, (today) I decided to put some miles on the car and see if the needle would move, and sure enough after about 25 mile the needle was now just a little below half a tank. This is super weird because it seems to me like this confirms that the passenger side sending unit is now functioning normally, bur for some reason the driver side unit must be sending an empty signal? But if this is the case why did it show a quarter tank when I first turned the car on after installing the new pump and sensors? And what caused the needle to drop to zero after I added back in those 4 gallons I had on hand? My plan moving forward is to wait and see what happens. I have already tried disconnecting the battery and reconnecting it to see if that reset the computer, no luck. So the moral of this story is twofold, yes one can replace a fuel pump and sending unit on an automatic C6 at home, and it can easily take all day if it is the first time you are attempting it. The second point to ask if anyone else has experienced anything similar after replacing a sending unit and how did you go about getting the gauge to read correctly? Thanks and happy driving!
07-05-2021, 01:13 PM
#2
Instructor
Member Since: Feb 2020
Location: Summerville, South Carolina
Posts: 200
Received 14 Likes
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14 Posts
Greetings fellow Vett enthusiasts,
Several months ago the fuel gauge in my 2006 Z51 Automatic started acting up. I was on a long road trip when it first threw me for a loop, I thought I was doing a good job of keeping an eye out on the fuel level when out of the blue the low fuel warning chime caught my attention. I was baffled, I thought I had just under a half tank of fuel left. I figured I must have zoned out as the miles passed. After filling the tank (it only accepted about 10 gallons at the pump) I was rather confused. Sure that the tank capacity was 18 gallons, meaning I still must have had 8 gallons on hand but the gauge had read empty. From then the problem manifested itself more and more frequently.
After searching the forums for answers, I became more certain that the sending unit was starting to go bad ( there are of course two units, one in each tank). From what I could tell, folks had been able to pull out the swap at home, but all the accounts I read were for manual transmission models, so I did not have a ton of confidence in attempting the job. Regardless after getting a quote for the job of nearly $2000, I decided to buy the parts (about $300 for the pump and a new sending unit for the right side) and attempt the job myself.
So this past Saturday I got the tools out and went to work at about 8 am. I started off by driving the front wheels onto ramps and then jacked up the rear end (not before breaking the lug nuts loose on the back wheels). I placed jack stands and removed the back wheels, pulled the wheel-wells, and removed the fuel tank access hatch on the right side wheel well (right=passenger side). From here I disconnected the "evap" lines from the passenger tank and the wires. Got under the car and removed the aluminum plates under each tank, they were bolted in with 5x bolts each, 15mm if I recall. at this point while laying under the car looking up I could see the cross-over tube, but the exhaust pipes were in the way and stopped my from getting my hands up to loosen the cross-over tube. So I removed the "H" pipe from the exhaust, sadly I am getting rather good at this procedure haha. Once this was out of the way I was able to get my hands where they needed to be, although it still took like another two hours of feeling around to get the cross-over pipe unhooked from the passenger side tank. Once that major achievement was finished I was able to drop the tank and slide it out from under the car (note this tank was empty as it drains first, then the driver side drains while driving).
After another good little while I got the old sending unit out and installed a new one. While I had the pressure relieved on the cross-over tube I went about dropping the driver side tank, it took another good hour to get the cross-over tube removed, the space is so tight, I can really see why a normal shop would rather drop the transmission. Long story short, I was able to get the new fuel pump installed, put the tanks back in their place. It only took me about 11 hours to get this far, haha (and counting, the wheels were still off at this point as well as the wheel wells, I did have the H pipe reinstalled). So the moment of truth, I reconnected the battery, and tried to start the car ( there were about 4 gallons of fuel in the tank at this point). I held down the start button for about 5 seconds, the starter turned the engine over but no luck.
On the second attempt (after the fuel system was re-pressurized) the engine came to life after about two seconds of holding down the start button. Success! At this point in time the fuel gauge read about 1/4 full. I turned the car off and restarted, it roared to life! I turned it off and got to work reinstalling the wheel wells, tires and lowered the car. at this point I re-added some fuel from a gas can that I had used to lower the fuel level in the tank prior to starting the project to make the tank driver side tank lighter to handlle, I had 2x 2 gallon cans that I added back to the tank (4 gallons total). Here's where things got weird, After getting back in the car and starting it up, the gas gauge now showed the needle on empty (no warnings or chimes though). I thought this was really odd and decided to drive to the local gas station and top off. After filing the tank (it accepted about 10 gallons) and starting the car, the gauge now read half full. Very strange. I decided to call it a night.
The next day, (today) I decided to put some miles on the car and see if the needle would move, and sure enough after about 25 mile the needle was now just a little below half a tank. This is super weird because it seems to me like this confirms that the passenger side sending unit is now functioning normally, bur for some reason the driver side unit must be sending an empty signal? But if this is the case why did it show a quarter tank when I first turned the car on after installing the new pump and sensors? And what caused the needle to drop to zero after I added back in those 4 gallons I had on hand? My plan moving forward is to wait and see what happens. I have already tried disconnecting the battery and reconnecting it to see if that reset the computer, no luck. So the moral of this story is twofold, yes one can replace a fuel pump and sending unit on an automatic C6 at home, and it can easily take all day if it is the first time you are attempting it. The second point to ask if anyone else has experienced anything similar after replacing a sending unit and how did you go about getting the gauge to read correctly? Thanks and happy driving!
Several months ago the fuel gauge in my 2006 Z51 Automatic started acting up. I was on a long road trip when it first threw me for a loop, I thought I was doing a good job of keeping an eye out on the fuel level when out of the blue the low fuel warning chime caught my attention. I was baffled, I thought I had just under a half tank of fuel left. I figured I must have zoned out as the miles passed. After filling the tank (it only accepted about 10 gallons at the pump) I was rather confused. Sure that the tank capacity was 18 gallons, meaning I still must have had 8 gallons on hand but the gauge had read empty. From then the problem manifested itself more and more frequently.
After searching the forums for answers, I became more certain that the sending unit was starting to go bad ( there are of course two units, one in each tank). From what I could tell, folks had been able to pull out the swap at home, but all the accounts I read were for manual transmission models, so I did not have a ton of confidence in attempting the job. Regardless after getting a quote for the job of nearly $2000, I decided to buy the parts (about $300 for the pump and a new sending unit for the right side) and attempt the job myself.
So this past Saturday I got the tools out and went to work at about 8 am. I started off by driving the front wheels onto ramps and then jacked up the rear end (not before breaking the lug nuts loose on the back wheels). I placed jack stands and removed the back wheels, pulled the wheel-wells, and removed the fuel tank access hatch on the right side wheel well (right=passenger side). From here I disconnected the "evap" lines from the passenger tank and the wires. Got under the car and removed the aluminum plates under each tank, they were bolted in with 5x bolts each, 15mm if I recall. at this point while laying under the car looking up I could see the cross-over tube, but the exhaust pipes were in the way and stopped my from getting my hands up to loosen the cross-over tube. So I removed the "H" pipe from the exhaust, sadly I am getting rather good at this procedure haha. Once this was out of the way I was able to get my hands where they needed to be, although it still took like another two hours of feeling around to get the cross-over pipe unhooked from the passenger side tank. Once that major achievement was finished I was able to drop the tank and slide it out from under the car (note this tank was empty as it drains first, then the driver side drains while driving).
After another good little while I got the old sending unit out and installed a new one. While I had the pressure relieved on the cross-over tube I went about dropping the driver side tank, it took another good hour to get the cross-over tube removed, the space is so tight, I can really see why a normal shop would rather drop the transmission. Long story short, I was able to get the new fuel pump installed, put the tanks back in their place. It only took me about 11 hours to get this far, haha (and counting, the wheels were still off at this point as well as the wheel wells, I did have the H pipe reinstalled). So the moment of truth, I reconnected the battery, and tried to start the car ( there were about 4 gallons of fuel in the tank at this point). I held down the start button for about 5 seconds, the starter turned the engine over but no luck.
On the second attempt (after the fuel system was re-pressurized) the engine came to life after about two seconds of holding down the start button. Success! At this point in time the fuel gauge read about 1/4 full. I turned the car off and restarted, it roared to life! I turned it off and got to work reinstalling the wheel wells, tires and lowered the car. at this point I re-added some fuel from a gas can that I had used to lower the fuel level in the tank prior to starting the project to make the tank driver side tank lighter to handlle, I had 2x 2 gallon cans that I added back to the tank (4 gallons total). Here's where things got weird, After getting back in the car and starting it up, the gas gauge now showed the needle on empty (no warnings or chimes though). I thought this was really odd and decided to drive to the local gas station and top off. After filing the tank (it accepted about 10 gallons) and starting the car, the gauge now read half full. Very strange. I decided to call it a night.
The next day, (today) I decided to put some miles on the car and see if the needle would move, and sure enough after about 25 mile the needle was now just a little below half a tank. This is super weird because it seems to me like this confirms that the passenger side sending unit is now functioning normally, bur for some reason the driver side unit must be sending an empty signal? But if this is the case why did it show a quarter tank when I first turned the car on after installing the new pump and sensors? And what caused the needle to drop to zero after I added back in those 4 gallons I had on hand? My plan moving forward is to wait and see what happens. I have already tried disconnecting the battery and reconnecting it to see if that reset the computer, no luck. So the moral of this story is twofold, yes one can replace a fuel pump and sending unit on an automatic C6 at home, and it can easily take all day if it is the first time you are attempting it. The second point to ask if anyone else has experienced anything similar after replacing a sending unit and how did you go about getting the gauge to read correctly? Thanks and happy driving!
07-05-2021, 01:38 PM
#3
Le Mans Master
1) installation of a late-model sender in an early-model car or vice versa
2) a mechanical screwup such as a jammed float arm or leaking internal fitting
A connector left unplugged would throw a code.
If your gas gauge is reading backwards, it's number 1.
07-05-2021, 01:45 PM
#4
Instructor
Member Since: Feb 2020
Location: Summerville, South Carolina
Posts: 200
Received 14 Likes
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Weird fuel gauge readings following replacement of a fuel level sender are usually caused by:
1) installation of a late-model sender in an early-model car or vice versa
2) a mechanical screwup such as a jammed float arm or leaking internal fitting
A connector left unplugged would throw a code.
If your gas gauge is reading backwards, it's number 1.
1) installation of a late-model sender in an early-model car or vice versa
2) a mechanical screwup such as a jammed float arm or leaking internal fitting
A connector left unplugged would throw a code.
If your gas gauge is reading backwards, it's number 1.
07-05-2021, 01:55 PM
#5
Le Mans Master
07-05-2021, 02:47 PM
#6
Instructor
Member Since: Feb 2020
Location: Summerville, South Carolina
Posts: 200
Received 14 Likes
on
14 Posts
Did your pump come with a level sender installed? It needs to be the later style to work with an '08. You can check if this is the problem by monitoring the sender voltage with a scan tool or volt meter as you drive around. If you do have a backwards sender, you can either replace it or use tuning software to reverse the fuel level table.
07-05-2021, 04:22 PM
#7
Le Mans Master