2004 GTO LS1 swap to 71 chevelle wont start after running and driving
12-07-2014, 11:01 PM
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2004 GTO LS1 swap to 71 chevelle wont start after running and driving We got the car running. Drove to work. Would not start to get home. Acts like it wants to start but wont. Few questions. WE have no codes when communicating with the PCM
1. if the oil sending unit was not working, would it start?
2. Would low fuel pressure prevent starting?
3. Could the crank or cam sensor go bad that suddenly and prevent starting?
We have voltage to the coils. injectors seem to be working. Plugs seem to be getting fire. We definitely have fuel but no sure of pressure. checked all wires and voltages, seem to be ok.
Ideas?
1. if the oil sending unit was not working, would it start?
2. Would low fuel pressure prevent starting?
3. Could the crank or cam sensor go bad that suddenly and prevent starting?
We have voltage to the coils. injectors seem to be working. Plugs seem to be getting fire. We definitely have fuel but no sure of pressure. checked all wires and voltages, seem to be ok.
Ideas?
12-07-2014, 11:45 PM
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1)no it will not make it not start/run
2)yes
3)yes
Make sure wiring wasnt on headers and got burnt or something. Ive seen this and similar multiple times after virgin runs.
2)yes
3)yes
Make sure wiring wasnt on headers and got burnt or something. Ive seen this and similar multiple times after virgin runs.
12-08-2014, 06:15 AM
#3
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Real quick checklist:
Does the fuel pump cycle with key in run position?
Do you have 12v to the pink and orange wires to the ECU (E40?)
Do the relays click when you move key to run position?
Agreed with all 3 points from rennat2006 . I had the cam sensor go away suddenly. All of a sudden would not start, sometimes a series of small backfires, then it would start and run, but just ok.
Does the fuel pump cycle with key in run position?
Do you have 12v to the pink and orange wires to the ECU (E40?)
Do the relays click when you move key to run position?
Agreed with all 3 points from rennat2006 . I had the cam sensor go away suddenly. All of a sudden would not start, sometimes a series of small backfires, then it would start and run, but just ok.
12-08-2014, 06:25 AM
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Real quick checklist:
Does the fuel pump cycle with key in run position?
Do you have 12v to the pink and orange wires to the ECU (E40?)
Do the relays click when you move key to run position?
Agreed with all 3 points from rennat2006 . I had the cam sensor go away suddenly. All of a sudden would not start, sometimes a series of small backfires, then it would start and run, but just ok.
Does the fuel pump cycle with key in run position?
Do you have 12v to the pink and orange wires to the ECU (E40?)
Do the relays click when you move key to run position?
Agreed with all 3 points from rennat2006 . I had the cam sensor go away suddenly. All of a sudden would not start, sometimes a series of small backfires, then it would start and run, but just ok.
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12-08-2014, 07:42 PM
#8
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When I first did my swap, I put the sender for my aftermarket temp sensor in the drivers side head where the original one was. After it ran a while, it refused to start. It turns out that you have to keep the original sensor in place so that the computer knows what temperature the engine is (and not just the gauge).
This probably isn't your problem....but if it is, reinstall the original sensor in the drivers side head, and install your temp sender for your gauge in the plugged hole at the rear of the passenger head.
This probably isn't your problem....but if it is, reinstall the original sensor in the drivers side head, and install your temp sender for your gauge in the plugged hole at the rear of the passenger head.
12-08-2014, 10:46 PM
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tonights troubleshooting on chevelle LS swap 1. oil sending unit wired correctly. had to splice worried about wires. oil pressure comes up to 60 psi while cranking
2. crank sensor 5.1 kohms. Checked all wires and plug.
3. cam sensor 5.1 kohms
4. all battery and ignition power to pcm correct.
5. no codes in diagnostics. all sensors seem to be working when cranking motor.
6. noid lights are bright the first few cranks and then get dim as I continue to crank.
7. Spark plugs getting fire.
8. fuel pressure really weird. I am using a Mallory 11106m pump and corvett bypass regulator. used my new tester and got over 100 psi. If I leave key on and just wait, pump begins to sound in a bind and makes weird noise like running away. Also, when this first happened the valve? (check valve?) in the middle of the fuel rail was clicking wildly. Clicks some now but not nearly like it was. Too much pressure? Can that lock up injectors and not allow them to open? If is was carbureted, I would squirt some gas in carburetor and see if it fires. How do you do this test on an LS1? Injectors are firing but is gas squirting? removed line and pump is pumping. Check filters and return lines. all clean and working.
9. I am thinking all sensors, neutral switch, anything that would prevent start is ok because injectors and plugs are firing. if anything was telling the computer not to start, it would not fire, correct?
It tried to start a few times while I was cranking but would not of course.
2. crank sensor 5.1 kohms. Checked all wires and plug.
3. cam sensor 5.1 kohms
4. all battery and ignition power to pcm correct.
5. no codes in diagnostics. all sensors seem to be working when cranking motor.
6. noid lights are bright the first few cranks and then get dim as I continue to crank.
7. Spark plugs getting fire.
8. fuel pressure really weird. I am using a Mallory 11106m pump and corvett bypass regulator. used my new tester and got over 100 psi. If I leave key on and just wait, pump begins to sound in a bind and makes weird noise like running away. Also, when this first happened the valve? (check valve?) in the middle of the fuel rail was clicking wildly. Clicks some now but not nearly like it was. Too much pressure? Can that lock up injectors and not allow them to open? If is was carbureted, I would squirt some gas in carburetor and see if it fires. How do you do this test on an LS1? Injectors are firing but is gas squirting? removed line and pump is pumping. Check filters and return lines. all clean and working.
9. I am thinking all sensors, neutral switch, anything that would prevent start is ok because injectors and plugs are firing. if anything was telling the computer not to start, it would not fire, correct?
It tried to start a few times while I was cranking but would not of course.
12-09-2014, 10:41 PM
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Hard to believe but the aftermarket fuel pump developed too much pressure and destroyed the regulator. I was actually pushing well over 100 psi on a stock fuel rail and injectors. fouled my plugs. Found gas in oil. Burned off plugs, modulated pressure by hand switching pump on and off and it started and ran. Not sure how this happened but I know what to fix. Thanks for helping.