Hi

Friend of mine just got 1996 Ford E350 7.3L Disel(cube van) with about 220K on engine. Probem with this truck is that he would start when is cold and it idle normally for about few minutes. After that he would eather stall or start idling roughly like it has no enought power or shortage of gasoline. When you press the gas padel when is idling roughly RPM goes up but the engine is shaking and you can see that has no power. He changed fuel filter but still the same. Any idea is welcomed.

 

I had trouble with my 250 diesel stalling at low speed. my mechanic said that there is a sensor on the front pulley that shuts off the fuel pump when the engine stops. this sensor was giving false readings and intermittently turning off the fuel pump. maybe something to check.

Larry

 

First....

Is there any CEL (check engine light), smoke??

On the early PSD's it's VERY common for possibly 'both' the harness connectors to burn/melt at the outer valve cover/s connectors, AND/OR the 'inside' the valve covers stub harness/s around the glow control circuit pins.. They are the ‘outer most’ connector/pins for the glow circuits, and sometimes will take out the neighboring injector connections as well. Usually will set a DTC (diagnostic trouble code) for high/low fault, circuit failure, Injector Driver codes.. To help isolate the miss/rough condition the system really should be scanned, as well as a 'cylinder contribution/balance test' prior to any work or guessing as to electrical/mechanical causes/failures.. With the kind of mileage that this engine has, it could easily be an injector O-ring failure/s, (if no prior repairs) injectors, or multiple failures/causes.. If a serious enough high pressure oil/injector o-ring leak,, not only might it scan as higher IPR %, but a needed contribution test and scan would give an indication as to ‘which cylinder/s’ are dropping out from normal running spec and any other running/idle ‘parameter’ problems for some direction as to cause.. You might try a wiggle test on the harness/connectors at the covers after if it's run/warmed and then starts to misfire.. If you can hear it smooth some, or you see a 'bulge' in the connectors at the outer portion on the connector plugs, separate them and look for corroded/burned or backed/pushed out pins.. If so, then the harness needs to be repaired.. There could be other causes too, but seeing the mileage, and known issues with the early PSD, and a higher mileage engine, this is where I would start.. A fuel related issue would ‘most likely’ affect it more off idle, mechanical lift pump, pick-up screen, supply/volume ect... And being that this engine seems to just be ‘dropping’ off cylinder contribution/performance, follows a heating/warming pattern, and is still able to pull without a complete stall on accell? And ‘if’ fuel related would/should worsen when the demand for fuel increases with throttle angle,,, leads me to believe its injector related.. Either by connection failures, injectors themselves, or o-rings.. O-ring failures will sometimes not show up as severe with cold engine temps, as the oil tends to be thicker (unless severe leaks) and the injector will still fire ‘sufficiently’ while cold, and when the oil heats will leak past the o-rings and worsen as the engine heats to normal temps.. Although a fuel pressure test as well certainly wouldn’t hurt, as lift/fuel pumps do fail AND leak with the given mileage.. If it were being ‘starved’ enough for fuel at idle due to filter, or fuel delivery/pressure, hot or cold, it would have most likely have severe pulling or reving issues in most cases, not to mention a misfire code/s being stored.. Some times an o-ring failure or the beginnings of one, can be ID’d by looking into the small screen mounted in the fuel pressure regulator on the side of the fuel/water separator.. Or sometimes seen in the filter housing and filter as black particles/black pieces…

Could be any of the above, and a scan would shorten the search , or at the least help tell you what its not..

 

Thanks for the input.

My friend took the truck to the garage because he got contract with some delivery company and he has to have ready truck as soon as posible but I just want to thank you for your input and to let you know that Hayapower you were right. Mechanic called today to say that harness and injectors were gone.

Thanks.

 

Glad it was an easy find...