Engine/Transmission (1998.5 - 2002) no start when warm

[Walleye mike]

Had a no bus problem few weeks ago. Last week came home and truck sat for 1/2 hour and would not start. I noticed that there was no fuel pressure. When I would turn the key key on i would get the little blip of the lift pump. Put a new lift pump in thought it was fine. Same thing today after it sat 1/2 hour it wont start. it cranks, shows no fuel pressure, when i bump the starter no lift pump. I wired a lead to the battery so lift pump runs and it stiil sranks but wount start. have 1693 code but think that was from the no bus last week? When it runs it runs great.

 

[JLandry]

Mike,



It sounds like you have a bad ECM.



With the lift pump wired to come on when the ignition key is on, you can also try HOT WIRING THE VP44 to try and narrow down if it's the ECM or VP44 which has the problem. If the engine will start and run with the VP44 hot wired, then the ECM is likely at fault.



John L.

 

[Walleye mike]

have not tried to hot wire the vp44, but have had the codes cleared, then took it to a former dodge garage after a no start, still no codes. wait a while and it will start. but when it cranks, it dont fire and the only thing goofy is when you bump the starter the lift pump wont run. but when you turn the key on ill get the little blip of the lift pump. It has not done it for a bit now, but still thinking the ECM?

 

[JLandry]

... but still thinking the ECM?

That's definitely abnormal behavior from the ECM.



John L.

 

[Houser]

Next time it wont start warm try unplugging the lift pump. I know that sounds wierd but some worn out VP44s wont start warm with good LP pressure. but will with none.



Mike

Palmer, Ak

 

[Bob4x4]

Be very carefull when trying to hot wire the VP hitting the wrong wire will fry it. The use of a hot box is the safe way.

 

[Walleye mike]

Today while running the CEL came on, check the code and its for the crankshaft position sensor, if the crankshaft sensor had no reading would this cause a no start?also if there was no reading would the lift pump not run when starter bumped?

 

[Bob4x4]

Crank sensor failures are very common. Yes it will cause a no start. They will run with a bad sensor and still have a no start

 

[Houser]

Its starts OK cold. But not OK warm. I don't think the crank sensor can tell the difference.
The VP can. Try the lp disconnect first. It doesn't cost anything.

Houser