bloe17
Newbie
Hey there,
I have a 1991 c1500 5.7l 250k miles. Bone stock.
I just ran WINALDL to help diagnose my knocking engine.
Truck only starts after a long crank once the Oil Pressure Switch kicks on the fuel pump, therefore bypassing the ECM- right?
Truck does NOT prime fuel with key on, engine off. It seems to be knocking, especially at idle. The knocking is present but sounds less evident at higher RPMs. What is very weird, is the knocking was a problem when the prime was working as well. Now it ALSO doesn't prime fuel. So I assumed fuel pump, but my BLM is right at 128 (perfect?) ruling that out. I even removed the injectors from the throttle body, KO to prime and fuel DUMPED down the throttle body, but not a drop flows with injectors in place (ruling out FPR?). I have 12v to each injector wire. I replaced one of the injectors as a test, and nothing changed. This tells me the ECM is not grounding the injectors for some reason? Have tried several aftermarket ICMs, installed a new aftermarket distributor/PU coil which changed nothing as well.
This truck used to have a very notable 2 second whine while priming, now the pump barely makes a whine- but it does whine to a small degree. This made me think the fuel pump is the issue, but why would my BLM be perfect if so? 5v ref, 12v supply, ground wire to fuel pump are all good traced to the ECM/FPR.
Are my MAP levels low? I do have some slight oil leaking from the intake manifold gasket.
ECM is a brand new 1227747 with OEM prom ARJT
No CEL or codes stored
What could this random fluctuation of sensor information mean in my datalog?
Do any of the other readings seem off?
Thanks!
I have a 1991 c1500 5.7l 250k miles. Bone stock.
I just ran WINALDL to help diagnose my knocking engine.
Truck only starts after a long crank once the Oil Pressure Switch kicks on the fuel pump, therefore bypassing the ECM- right?
Truck does NOT prime fuel with key on, engine off. It seems to be knocking, especially at idle. The knocking is present but sounds less evident at higher RPMs. What is very weird, is the knocking was a problem when the prime was working as well. Now it ALSO doesn't prime fuel. So I assumed fuel pump, but my BLM is right at 128 (perfect?) ruling that out. I even removed the injectors from the throttle body, KO to prime and fuel DUMPED down the throttle body, but not a drop flows with injectors in place (ruling out FPR?). I have 12v to each injector wire. I replaced one of the injectors as a test, and nothing changed. This tells me the ECM is not grounding the injectors for some reason? Have tried several aftermarket ICMs, installed a new aftermarket distributor/PU coil which changed nothing as well.
This truck used to have a very notable 2 second whine while priming, now the pump barely makes a whine- but it does whine to a small degree. This made me think the fuel pump is the issue, but why would my BLM be perfect if so? 5v ref, 12v supply, ground wire to fuel pump are all good traced to the ECM/FPR.
Are my MAP levels low? I do have some slight oil leaking from the intake manifold gasket.
ECM is a brand new 1227747 with OEM prom ARJT
No CEL or codes stored
What could this random fluctuation of sensor information mean in my datalog?
Do any of the other readings seem off?
Thanks!