ok Right now I'm dealing with one of our company's trucks, a '99 F-350 V10 6.8L at work that is pretty much throwing everyone through a loop. It will run really nice for a few minutes bog out like its trying to stall but bring itself back sometimes but othertimes it will just stall out. but it will start back up and do the same thing again. I have been working on the thing now for 2 days and well its a nightmare. The first Tech that looked at replaced the fuel pump didn't make a difference so the shop forman tested out the electrical system on it a claims that the fuel pump is cutting off for some reason and is claiming the PCM is bad, however I have my doubts and today I was checking out and discovered the IAC was not working properly so I replaced it yet it does fix the issue we are experiencing with the truck.
I cold really use some help to find whats wrong with this thing, I have run a Snap On Brick on it several times to get live data and all fuel system reading seem normal right to stall then they just drop.

So far the Fuel pump has been replaced, the Fuel pressure regulator has been tested, the IAC has been replaced, the Mass Air flow has been tested, had multiple fuel pressure tests ran and had had live feeds ran from it all to no avail ....

so if anyone has any idea what is wrong with this truck then Please help me! thank you

-Chris

 

anyone?

 

have you checked for loose or broken ground wires? and to be sure of the fuel pumps working order, run a jumper wire from battery. that would atleast rule out a variable.

 

actually we went through every wire on the truck, we ended up shipping it off to the dealer to get it diagnosed, as our shop really isn't equipped for major electrical diagnostics, and its been there for a week now and they haven't even figured it out yet, lol

 

they haven't must be something special. lol. well anyhow let me know when they do. im interested now.

 

as entertaining as it is ... out of all the thing possible of course it was something really stupid wrong with it .... there was a relay that somehow got itself unplugged ..... and it must of really been hidden becasue 3 different people didn't see it and it took the dealership 2 weeks to find it

 

wow... a hair puller. lol. it most have been buried down in there like you said. i cant believe that it took the dealership that long though.

 

i have an o6 350 but with the diesel, not the V10 and it is having the same problem...fuel pumps, filters, injectors and tank later it is still doing it...it has been at the shop for 4 days now and they have not a clue what it is....i had it floored the other day and it was struggling to do 10mph so i could get off the road and they keep running diagnostics on it to try and find anything but it doesnt point them anywhere..now that i see what your problem is so maybe i can tell them to look for that haha

 

what relay was disconnected when you found it? i just got off the phone with the dealership and they still cant find anything

 

It was hidden under the hood near the battery actually.