Please accept my apologies but I wasn't sure where to post this and I am at a loss for where to go next. I know this is long but I tried to include everything I’ve checked and my results.
I have a 1982 CJ7 Jeep 6 cyl 4.2 that was converted to the Mopar MPI Fuel Injection with a 1995 PCM and a TJ 97 Jeep fuel injection single rail system and need some help. I thought I should post hear since the fuel pressure specs follow the 97 TJ.
Two weeks ago I went to start it and the Jeep was running rough. It is a little slow to start so I thought it might be the fuel pump. I checked the codes and it had a code for the #2 injector (stating it is a bad relay either constant open or closed). When I listen to the injector with a stethoscope it seems to be pulsing correctly. If I pull the wire on the #2 injector it changes the idle for a moment before the computer tries to correct the idle to the original rough running. After resetting the computer, it has not thrown the code again but it still runs rough. That being said, I haven't put more than 10 miles on it since the computer was reset and I don't know how many miles are required for the computer to throw the code again on a 1995 PCM. I checked all spark plugs and each are firing correctly. That led me back to the fuel pressure.
Below are my fuel pressure readings. My understanding is that it should be 49 PSI +/- 5 PSI on a 97 TJ so I realize I am on the high side according to the gauge readings listed below. But pressing the pressure gauge bleeder button took it to 52 PSI which should have been in spec (excluding volume drop to injectors I suppose) but it still ran rough).
Static Prime PSI = 11. If I reset the gauge and turn the key on again without starting it, the pressure goes to 15, recycle w/the same process and I got 27 PSI (without running).
Static Prime PSI Leak down at 2 minutes from 27 PSI dropped to 26 PSI
Running PSI at idle = fast pulse between 54 and 59 PSI
Running PSI at 2k RPM = pulse from 56 to 58 PSI
After Running Leak Down:
Initial PSI after turning the engine off = 53 PSI
2.5 minute leak down = 54 PSI
After running and retesting the prime again it primed to 50 PSI with first turn of the key to on. Then I left the key on for 2 minutes to test the prime drop PSI and it increased 54
I pressed the pressure release (fuel bleed line) on the fuel pressure gauge while it was running and the PSI went to a fairly steady 52 PSI. The volume appeared to be good and the fuel appeared clean with no water. It still ran rough.
Any thoughts on what to try next? Does it sound like a fuel pump going bad, a clogged fuel injector or maybe a bad PCM? I realize it could be a bad regulator but I don't have a vacuum line running to it since it is on the frame rail next to the gas tank. It was an adapted part of the kit.
I’m at a loss on what to check next and will GREATLY appreciate your help!
I have a 1982 CJ7 Jeep 6 cyl 4.2 that was converted to the Mopar MPI Fuel Injection with a 1995 PCM and a TJ 97 Jeep fuel injection single rail system and need some help. I thought I should post hear since the fuel pressure specs follow the 97 TJ.
Two weeks ago I went to start it and the Jeep was running rough. It is a little slow to start so I thought it might be the fuel pump. I checked the codes and it had a code for the #2 injector (stating it is a bad relay either constant open or closed). When I listen to the injector with a stethoscope it seems to be pulsing correctly. If I pull the wire on the #2 injector it changes the idle for a moment before the computer tries to correct the idle to the original rough running. After resetting the computer, it has not thrown the code again but it still runs rough. That being said, I haven't put more than 10 miles on it since the computer was reset and I don't know how many miles are required for the computer to throw the code again on a 1995 PCM. I checked all spark plugs and each are firing correctly. That led me back to the fuel pressure.
Below are my fuel pressure readings. My understanding is that it should be 49 PSI +/- 5 PSI on a 97 TJ so I realize I am on the high side according to the gauge readings listed below. But pressing the pressure gauge bleeder button took it to 52 PSI which should have been in spec (excluding volume drop to injectors I suppose) but it still ran rough).
Static Prime PSI = 11. If I reset the gauge and turn the key on again without starting it, the pressure goes to 15, recycle w/the same process and I got 27 PSI (without running).
Static Prime PSI Leak down at 2 minutes from 27 PSI dropped to 26 PSI
Running PSI at idle = fast pulse between 54 and 59 PSI
Running PSI at 2k RPM = pulse from 56 to 58 PSI
After Running Leak Down:
Initial PSI after turning the engine off = 53 PSI
2.5 minute leak down = 54 PSI
After running and retesting the prime again it primed to 50 PSI with first turn of the key to on. Then I left the key on for 2 minutes to test the prime drop PSI and it increased 54
I pressed the pressure release (fuel bleed line) on the fuel pressure gauge while it was running and the PSI went to a fairly steady 52 PSI. The volume appeared to be good and the fuel appeared clean with no water. It still ran rough.
Any thoughts on what to try next? Does it sound like a fuel pump going bad, a clogged fuel injector or maybe a bad PCM? I realize it could be a bad regulator but I don't have a vacuum line running to it since it is on the frame rail next to the gas tank. It was an adapted part of the kit.
I’m at a loss on what to check next and will GREATLY appreciate your help!