Hi. My -96 F350 started to run badly today. First I thought it was the fuel filter because it felt like it didn't get enough diesel so I blew the filter clean and after that it started to run properly again for a while.
But then later on the trouble came back and finally it wouldn't run at all.

I have a diesel warmer in the truck so I tried that and i worked as i should so I have diesel all the way to the fuel filter...

So I wonder, could it be that little fuel pump thingie behind the filter that is broken?


Sorry bout my english, I'm from Sweden...

 

Replace the filter. Blowing it out did nothing.

Also check fuel pressure at the filter housing. Should be at least 40psi at idle

 

I don't have idle right now. The damn thing will not start.

 

I've never seen a mechanical fuel pump out right fail and stop pumping fuel. Typically they start leaking more and more fuel in the V of the engine and down the back right hand side of the engine. The pump leaks so much fuel that you end of replacing it long before it no longer pumps fuel.

Drain the fuel bowl and replace the fuel filter as suggested. Could also be the screen at the FPR is gunked up and plugged. Pull it and clean it. Is it cold? Diesel jelling? These could also be issues plugging up the fuel filter or screen. Add some Diesel 911 (or equivalent) to the fuel filter bowl to eliminate jelling from not running winterized diesel.

There is a schraider valve on the fuel rail, left side of engine. Put a tire pressure gauge on it and have someone crank the engine. Should register around 40 psi or more when cranking the engine.

 

Thanks for the answer. I'll try that.

 

After a while on youtube I have another possible solution.

There is a fiew that's had problems with their 7.3 diesel injector harness falling of inside wich makes the engine run exactly like mine did.

That would also explain why it ran badly, then good and then bad again if the harness jiggled itself loose...

 

Fuel issues are not intermittent & the FPR screen will not cause a no start . You may be on the right track with the wiring. But , the truck should start & run on 4 cyls . ...Is it cold where you are ?Are you up for pulling the valve covers ?

 

thats more of a nbs truck problem thats why the 50 cent mod repairs it

 

Maybe they both fell off

Its under freezing here. I got the truck to run badly at first, as it wouldn't fire on all cylinders and it ran bad at idle with a steady rpm but then it just died. The engine shaked as a mental so maybe the other harness went because of that..

I have to look unther the valve covers just to be shure at least.

 

CHECK FUEL pressure. These pumps crap out all the time

 

When you crank it over does the tach move? I've seen a failing CPS make the truck run poorly like that - shaking, missing, stalling. Usually the truck just dies when it fails and the tach does not move when the engine is turning. Another possibility to check and eliminate. That sensor fails more than any other on the truck and with out it telling the computer when to fire the injectors the truck will not run. Replace it with another one just to eliminate it as a possible problem. I always carry several spares in my truck as it is the number one reason to be stranded on the side of the road. Keeping extras on hand has allowed me to help other PSD owners broken down on the side of the road several times.

 

I repaced the CPS half a year ago but when that went the engine just shut off completely.

I've got a spare in the glove box so if the injector harness looks like they should I'll replace that aswell.

 

There was no problem with the injector harness...

Didn't have a fuel preassure gauge with me to day but I loosen the bolt a bit and a friend run the starter. It come some diesel but it didn't look like 40 psi. I will check tha again to morrow.

If that pressure is low could it be the fuel pump anyway?

 

My experience with fuel pumps failing is that they leak fuel out of the weep hole on the right under side of the pump. The V of the engine has a puddle of diesel sitting in it and the diesel then runs down the drain hole on the back right side of the engine and leaves a puddle on the floor. I can smell it when it starts to go and I can see the leak on the floor under the truck. This leak gets steadily worse. I have never had a loss of fuel pressure as a result of a failing fuel pump but I replace it when I see it is leaking. Typically fuel pumps last me 120,000 miles or so before they begin to leak. Check the V of the engine and see if it is dry. Other people may have had other experiences with fuel pump failure than I have. I just installed my third pump about a month ago.

You can use a tire pressure gauge to test the fuel pressure. Crank the motor and it will pulsate up with each pump of the diaphragm. Keep cranking until the gauge stops moving. I typically run around 70 psi at idle but I have my FPR shimmed. Before shimming I was getting around 55-60 psi.

I've had CPS fail within a month of installing them. Sometimes with strange symptoms. Yes typically when they go the truck just stops running and the tach does not move anymore since the sensor is no longer sensing engine rotation. An easy place to start is to replace it with your back up and see if that solves your problem. If the problem persists then at least you know it is not your CPS. It only takes 10 minutes to eliminate that possibility.

Another place to check is your HPOP. Is there oil in it? Pull the plug on the left top side and make sure you can see oil almost filling the resivour. Without oil in the HPOP your injectors will not fire.

 

I have that leak from the fuel pump you are speaking of and it's not that bad, although exactly as you describe.

It shouldn't be able to run on a fiew cylinders with a bad CPS I think, not
as steady as it did anyway but as you said it's an easy thing to change..

My friend who is a boat mechanic went to what he thought was the fuel inlett to the injectors and loosen that while I cranked the engine but then instantly realised that it was the oil pressure (if it,s that you are talking about...)

edit: Oh I get it, the oil pump... Are the resivour located in front of the fuel filter? Trying to look for pics of it right now... Are the plug located on the resivour or the pump itself?

Sorry that I´m a pain in the *** but my english isn't that good and and I didn't get that part with the FPR... I've searched the web for pics of that and people are talking of a "screen" that can be clogged up but I don't get where that should be located.

I turn to you guys because last time when I had problem with the CPS I described the psymtomes and got the right diagnose from several guys right away. It's here the best collective knowledge bank I know of.

Thanks for your patience.