Help, C3 engine's not getting any gas.
Burning Brakes
Joined: Jan 2006
Posts: 1,154
Likes: 1
From: St Augustine FL
I am pretty sure their is some kind of delay. Im not sure the theory of operation. I imagine it would either be timed or a temperature thing. However you do have oil pressure and inital start....once the engine starts turning the pump starts pumping right?
Racer
Joined: May 2007
Posts: 285
Likes: 0
From: Ga.
Reading your thread I noticed that your voltage is still low. 8 or 9 volts will not fire the engine. Why is the voltage so low. Is the battery weak?
Put a battery charger on it, charge it then recheck your volts at the fuel pump relay. While charging the battery start verifying grounds at the fuel pump & relay. If they are any more than 3 ohms you probably have a bad ground.
You can bypass the oil pressure switch with a jumper to see if that is a problem.
Put a battery charger on it, charge it then recheck your volts at the fuel pump relay. While charging the battery start verifying grounds at the fuel pump & relay. If they are any more than 3 ohms you probably have a bad ground.
You can bypass the oil pressure switch with a jumper to see if that is a problem.
Thread Starter
Instructor
Joined: Apr 2008
Posts: 182
Likes: 0
From: New Jersey
Thanks!
Agreed, the engine's only turning over a few times before being starved. I assume it's to soon.
The low voltage is going to the fuel sensor(tank float). I assume that's ok. I'm not getting any voltage to the fuel pump. The battery is new and checked, ok.
I'll keep the oil pressure bypass in mind.
I'll get to it tomorrow. I ran out of time after checking the fp wiring.
Reading your thread I noticed that your voltage is still low. 8 or 9 volts will not fire the engine. Why is the voltage so low. Is the battery weak?
Put a battery charger on it, charge it then recheck your volts at the fuel pump relay. While charging the battery start verifying grounds at the fuel pump & relay. If they are any more than 3 ohms you probably have a bad ground.
You can bypass the oil pressure switch with a jumper to see if that is a problem.
Put a battery charger on it, charge it then recheck your volts at the fuel pump relay. While charging the battery start verifying grounds at the fuel pump & relay. If they are any more than 3 ohms you probably have a bad ground.
You can bypass the oil pressure switch with a jumper to see if that is a problem.
I'll keep the oil pressure bypass in mind.
I'll get to it tomorrow. I ran out of time after checking the fp wiring.
Le Mans Master
Joined: Apr 2001
Posts: 5,000
Likes: 1
From: Minneapolis, Mn USA
Im interested insolving this as someday I could be in the same boat as you.
The oil pressure switch is supposed to shut off the fuel pump if pressure goes below 4 PSI.
The fuel pump relay is there so while you are cranking, the pump gets supplied 12V to start up. Once X amount of time has passed the relay turns off and the pump continues operation from the 12V powered through the oil pressure switch.
12V supplied to the ALDL terminal G is in front of the relay (upstream) and not the same as jumpering the oil pressure switch and maybe the reason for the wacky relay action.
If you try jumpering if the oil pressure switch terminals (ORG to TAN/WHT), you might get normal operation- other than you can't turn off the pump. If would be a test to rule out the oil pressure switch.
Brent....
The oil pressure switch is supposed to shut off the fuel pump if pressure goes below 4 PSI.
The fuel pump relay is there so while you are cranking, the pump gets supplied 12V to start up. Once X amount of time has passed the relay turns off and the pump continues operation from the 12V powered through the oil pressure switch.
12V supplied to the ALDL terminal G is in front of the relay (upstream) and not the same as jumpering the oil pressure switch and maybe the reason for the wacky relay action.
If you try jumpering if the oil pressure switch terminals (ORG to TAN/WHT), you might get normal operation- other than you can't turn off the pump. If would be a test to rule out the oil pressure switch.
Brent....
Thread Starter
Instructor
Joined: Apr 2008
Posts: 182
Likes: 0
From: New Jersey
Too busy to work on the car today, I'll get to it tomorrow.
Is there an inertia switch on an '82 corvette and if so, where?
Is there an inertia switch on an '82 corvette and if so, where?
Last edited by 82crossfirevette; Apr 29, 2008 at 05:23 PM. Reason: spelling! haha, I'm fried today!
Instructor
Joined: Nov 2005
Posts: 129
Likes: 1
From: Plano Texas
The '82 crossfire has a specific 'timing circuit' connected to the ECM.
I have never heard of anyone who actually knows what it is there for, but this thread brings up an interesting possibility. It may be timing the oil pressure. Obviously ther is little if any pressure at startup . . . at least for a few nanos.
The most plausible explaination for the timing circuit is that it delays closed loop until a cold engine has been running a certain amount of time. But that has never been confirmed to my knowledge.
You can test the fuel pump by running 12V to the pump test terminal on the ALDL connector . . upper right corner. That bypasses the relay so you will at least know if the pump is working.
I have never heard of anyone who actually knows what it is there for, but this thread brings up an interesting possibility. It may be timing the oil pressure. Obviously ther is little if any pressure at startup . . . at least for a few nanos.
The most plausible explaination for the timing circuit is that it delays closed loop until a cold engine has been running a certain amount of time. But that has never been confirmed to my knowledge.
You can test the fuel pump by running 12V to the pump test terminal on the ALDL connector . . upper right corner. That bypasses the relay so you will at least know if the pump is working.
Thread Starter
Instructor
Joined: Apr 2008
Posts: 182
Likes: 0
From: New Jersey
The details of where I'm at now are on page 2 of this thread, 3 posts from the bottom.
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Burning Brakes
Joined: Jan 2006
Posts: 1,154
Likes: 1
From: St Augustine FL
Im interested insolving this as someday I could be in the same boat as you.
The oil pressure switch is supposed to shut off the fuel pump if pressure goes below 4 PSI.
The fuel pump relay is there so while you are cranking, the pump gets supplied 12V to start up. Once X amount of time has passed the relay turns off and the pump continues operation from the 12V powered through the oil pressure switch.
12V supplied to the ALDL terminal G is in front of the relay (upstream) and not the same as jumpering the oil pressure switch and maybe the reason for the wacky relay action.
If you try jumpering if the oil pressure switch terminals (ORG to TAN/WHT), you might get normal operation- other than you can't turn off the pump. If would be a test to rule out the oil pressure switch.
Brent....
The oil pressure switch is supposed to shut off the fuel pump if pressure goes below 4 PSI.
The fuel pump relay is there so while you are cranking, the pump gets supplied 12V to start up. Once X amount of time has passed the relay turns off and the pump continues operation from the 12V powered through the oil pressure switch.
12V supplied to the ALDL terminal G is in front of the relay (upstream) and not the same as jumpering the oil pressure switch and maybe the reason for the wacky relay action.
If you try jumpering if the oil pressure switch terminals (ORG to TAN/WHT), you might get normal operation- other than you can't turn off the pump. If would be a test to rule out the oil pressure switch.
Brent....
Thread Starter
Instructor
Joined: Apr 2008
Posts: 182
Likes: 0
From: New Jersey
Update:
Here's what I've done so far.
New fuel assembly, fuel filter, fuel pump, fuel send/return/vapor lines at the tank, and fuel pump relay.
Here's where I'm at now.
1. I checked the pump by supplying 12v via the ALDL and pumping gas into a gas can, post fuel filter. It works fine.
2. After installing the new fuel pump relay, I got the same results. Nothing! The pump is not getting any voltage when I turn the ignition. However, when I give it 12v via the ALDL and crank the ignition key it works BUT only while I'm Cranking the key.
where do I go from here?
What controls the Fuel pump switch?
Could it be the Electronic Spark Control?
Could it be the ECM? it's original at 91K miles.
I have a high performance Accel chip sitting around so I swapped it with the original and got the same results.
I don't believe it's the engine. If I supply gas to the injectors the engine turns over without an issue. In addition, I don't believe it's the oil pressure unit since I'm not passing the "ignition" stage.
Help! - John
Here's what I've done so far.
New fuel assembly, fuel filter, fuel pump, fuel send/return/vapor lines at the tank, and fuel pump relay.
Here's where I'm at now.
1. I checked the pump by supplying 12v via the ALDL and pumping gas into a gas can, post fuel filter. It works fine.
2. After installing the new fuel pump relay, I got the same results. Nothing! The pump is not getting any voltage when I turn the ignition. However, when I give it 12v via the ALDL and crank the ignition key it works BUT only while I'm Cranking the key.
where do I go from here?
What controls the Fuel pump switch?
Could it be the Electronic Spark Control?
Could it be the ECM? it's original at 91K miles.
I have a high performance Accel chip sitting around so I swapped it with the original and got the same results.
I don't believe it's the engine. If I supply gas to the injectors the engine turns over without an issue. In addition, I don't believe it's the oil pressure unit since I'm not passing the "ignition" stage.
Help! - John
Last edited by 82crossfirevette; May 1, 2008 at 09:49 PM.
Le Mans Master
Joined: Apr 2001
Posts: 5,000
Likes: 1
From: Minneapolis, Mn USA
The oil pressure switch controls the fuel pump power after cranking times out. If you jumper its terminals, you will find out if this is your problem or not as the car will continue to run if jumpered. I haven't seen if you had any results from this test.
You also stated the wiring may not be correct. Make sure that is all sorted out.
I think you're almost there. Hope to hear you have it running this weekend or at least have the bad part on order
Brent....
You also stated the wiring may not be correct. Make sure that is all sorted out.
I think you're almost there. Hope to hear you have it running this weekend or at least have the bad part on order
Brent....
Thread Starter
Instructor
Joined: Apr 2008
Posts: 182
Likes: 0
From: New Jersey
Thanks Brent.
I wish it were the problem. I checked the ECM this morning and got nothing.
The "check engine" light doesn't come on when I turn the ignition on OR when I try to enter diagnostic mode, paper clip in the ALDL A/B terminals and ignition on. The bulb checked ok. Looks like the ECM's dead.
Zip can get the part but it'll take 4 weeks.
I'll try to find someone that has it stocked before I commit to Zip but I want to get the ball rolling. If anyone knows where I can get one, please fill me in.
I wish it were the problem. I checked the ECM this morning and got nothing.
The "check engine" light doesn't come on when I turn the ignition on OR when I try to enter diagnostic mode, paper clip in the ALDL A/B terminals and ignition on. The bulb checked ok. Looks like the ECM's dead.
Zip can get the part but it'll take 4 weeks.
I'll try to find someone that has it stocked before I commit to Zip but I want to get the ball rolling. If anyone knows where I can get one, please fill me in.
Burning Brakes
Joined: Jan 2006
Posts: 1,154
Likes: 1
From: St Augustine FL
http://cgi.ebay.com/ebaymotors/82-CO...m170214863467&
Copy the link. Its on EBaY right now Ends may 6th...you can probably ask the guy what he would take for it as a buy it now price and get it quicker.
Copy the link. Its on EBaY right now Ends may 6th...you can probably ask the guy what he would take for it as a buy it now price and get it quicker.
Thread Starter
Instructor
Joined: Apr 2008
Posts: 182
Likes: 0
From: New Jersey
http://cgi.ebay.com/ebaymotors/82-CO...m170214863467&
Copy the link. Its on EBaY right now Ends may 6th...you can probably ask the guy what he would take for it as a buy it now price and get it quicker.
Copy the link. Its on EBaY right now Ends may 6th...you can probably ask the guy what he would take for it as a buy it now price and get it quicker.
Last edited by 82crossfirevette; May 2, 2008 at 05:05 PM.
Racer
Joined: May 2007
Posts: 285
Likes: 0
From: Ga.
Have you done the CEL light circiut check to make sure that there is not a bad wire or ground. I think if you either ground the circuit from the ECM strip you can make the light come on. Please verify 1st. My contacts were bad on the bulb socket. I still had to change my ECM.
O'reilys can get you the ECM for 99.00 limetime warranty. Takes about 1 day. It is repaired by Cardone. Or you can contact them directly.
O'reilys can get you the ECM for 99.00 limetime warranty. Takes about 1 day. It is repaired by Cardone. Or you can contact them directly.
Thread Starter
Instructor
Joined: Apr 2008
Posts: 182
Likes: 0
From: New Jersey
Have you done the CEL light circiut check to make sure that there is not a bad wire or ground. I think if you either ground the circuit from the ECM strip you can make the light come on. Please verify 1st. My contacts were bad on the bulb socket. I still had to change my ECM.
O'reilys can get you the ECM for 99.00 limetime warranty. Takes about 1 day. It is repaired by Cardone. Or you can contact them directly.
O'reilys can get you the ECM for 99.00 limetime warranty. Takes about 1 day. It is repaired by Cardone. Or you can contact them directly.
I'll clean the bulb socket and look into the test you mentioned.
I ordered the Cardone from Advance Auto for $95. They have a storefront down the road if I need to return it.
Heel & Toe
Joined: Apr 2008
Posts: 20
Likes: 0
Where is the fuel pump relay?? Just bought new one and it does not match the electrical looking box behind the pass seat,under staorge box. New one has five pins in a row . One there is 3in a line and 3 in "T"cross pattern. Am I in the wrong place?
Thread Starter
Instructor
Joined: Apr 2008
Posts: 182
Likes: 0
From: New Jersey
1.Move your driver's seat up(if they're electrical)
2. Remove the battery
3. Remove the 4 bolts to the ECM and pull out the ECM. You can leave the ECM in the compartment still hooked up.
4. Remove the 2 bolts to the FP Relay. Move the carpeting hanging behind the driver's seat and look between the rise the drivers seat. The 2 bolts are accessible there.
5. Swap out the FPR and install in reverse;.
Enjoy!
Last edited by 82crossfirevette; May 4, 2008 at 04:43 PM.
Heel & Toe
Joined: Apr 2008
Posts: 20
Likes: 0
Thanks for the relay location been looking all over for it. Sound like I am two steps behind you. I replaced the relay, but When I test voltage at fuel pump end I get 8.5 volts on the pink wire and 0 on the brown. Which one is the power for the pump. Diagram was not real clear. The voltage shows up when cranking right? OR do Ihave to bypass the oil pressure switch. How do I do that? Any other ideas? Jeff