My 98.5 does something strange. This problem has been going on with this engine, the engine before this one, this VP, the old VP this FP, the last FP ETC.. I have been living with this for a while, winter is over and its back to being more of a pain. Here is the problem:

When cold the truck starts within the first few rotations. No problems whatsoever.

When the engine is Warm or hot (even if it has been sitting for a good while) the truck spins and spins before starting, like there is air in the fuel.. Now, before we go deciding thats the problem and I (like alot of others) have that connection on the back of the head leaking let me throw in the twist.. IF I roll start the truck, forwards or backwards it starts IMMEDIATELY.. Engine doesn't even make it a full round.. Strangely enough, it seems that even if I am ROLLING and the clutch is in and hit the starter it starts right up also..

Has anyone ever seen this problem before? Its weird.

Items replaced (not necessarily for this problem) with no help:

VP44
Lift pump
Engine
Cam sensor
Crank sensor
Batteries
Alternator
Starter
Probably more that I do not recall as the truck has 330k on her and still is worked daily..

Jason

 

im having the same problem with my 01 its got me dumb founded by the whole situation

 

Strange huh? Maybe someone can figure this out.. Yours is stock like mine, maybe thats the problem..

Jason

 

Is your lift pump stock? What is the fuel pressure? If it is too high you will get precisely the symptoms you are describing: bad starting with LP pumping because VP44 can't inject well; on push start, LP is not active so with zero FP, the VP44 injects right away and the LP instantly kicks in when the engine run signal is received by the ECM, so the engine runs normally immediately after start.

 

Try replacing fuel filter if not done recently. That is what mine was recently., Don' t buy from Dodge $50-70. $12 elswhere.

 

I replace mine every 10k or so.. seems to be a lot of trashy fuel these days.. Anyhow, it was recently replaced, and has been several times since this has been happening..

Jason

 

Paul, I just saw your post.. I am 100% stock other than tires and stereo.. I have been experimenting lately and found another strange twist. If I turn the key on, bump the starter and wait about 6 or more seconds it starts MUCH quicker most of the time. The bump of the starter causes the lift pump to run, I do not have a pressure gauge but I do have a low pressure light and it does not come on even at WOT with a load and the turbo singing..

Maybe I am overlooking the obvious!?

Jason

 

Jason,

You probably have a small air leak on the return side of the fuel system, the problem is finding it, I fought with my copper washers not sealing and causing the same problem, if the truck was parked downhill it was much less noticeable than parked with the nose uphill.

 

Well, I'm hoping thats the case but splain the roll start? Strange enough truck will even roll start AFTER trying to start with no no luck..

Jason

 

Hows about a bad connection? when you are in start you are pulling pretty hard on the electricial system. When roll starting, no such load. You might check voltages in start position at the key, start relay, and vp. I do not remember if the dodges have a low voltage code. You might check sensor voltages also. Good luck

 

I have no codes. I assume something like this myself, however I can't seem to nail it down.. I am wondering what else is powered from the "start" circuit?

Jason

 

Ok, so heres the latest.

I hooked up my code reader (even tho there was no MIL) and found that when the engine gets spun over communication is lost to one of the responding computers. Not sure which, although it is listed second on the Data page and ALWAYS shows some positive TPS reading which leads me to believe its the ECM.. Anyone have any idea where the ECM gets its power? The module does not seem to get power back until either the switch is turned off and on, or the engine starts (roll start).. I'm making progress here, just not real dang quick! Help?
Jason

 

How do you know? Are there any codes? You said earlier that you have a ffuel leak at the back of the head. If this is the case, fix that 1st. (Always diagnose but don't go around the horn thinking problems are worse or more exotic than they are. Fix what you see.)

 

You must be mistaken, I have no fuel leak that I can see.. The codes I had were overboost and companion codes; why I do not know but they were there.. Got any ideas on where I can look next?

Thanks for the look!

Jason

 

I'd suggest that you take a look at the starter- the connections from the battery to the starter and the starter contacts and a very thorough look at the starter brushes.
Arcing on the starter brushes can lead to a lot of electrical noise that interrupts some communications.

HTH

AlpineRAM