1996 Ram 1500 5.9. Turn the key on, oil pressure light illuminates but check engine light does not. Can hear fuel pump running, engine spins but will not start.\ Let it sit with pump running for a minute, cycle key and now the check engine light is illuminated. Starts and runs fine. No codes but initailly when check engine light not lit scanner will say no comm. If you turn off engine it will retsrt but wait a bit and same situation arises. Any ideas?

Thanks,
Troy

 

Does the fuel pump continue to run while cranking when it won't start?

 

Good question. Hard to hear it as its cranking but Ill have my wife turn it over as I crawl under tank tonight. Will report back.

 

Check and see if you are getting spark when it won't start as well.

 

More details. Turn key on, oil light lit but no check engine. Fuel pump running...try to start and fuel pump stays running but there is no spark. wait 30 seconds or so with key on...cycle key and check engine light is now present.and fuel pump stops. Trucks starts and runs fine.

 

Does the fuel pump continue to run, even if you aren't cranking?

 

Yes, Initially when key on (No CEL) fuel pump runs constantly. Once CEL is present it acts normal.

Could this be a PCM issue even though it runs great? What's in charge of initial start up? Something acts like it doesn't see all the requirements to start when initially keyed on.

 

The PCM controls the fuel pump. It is supposed to run it for three seconds at initial key on, and then, only if it sees the engine turning. (via crank sensor) Since yours is staying on.... I would try swapping the relay first, and if that doesn't change anything, it likely is the PCM itself.

 

Thanks for the input/ideas! Will report back when fixed.!

 

Do I need to buy a PCM with my vin# installed or a junkyard unit from same yr with 5.9 be okay?