So I'm meeting some friends at a camp...get lost and to make it worse the truck shuts off while I'm lost! Just driving along and it shuts off. Fortunately one of my friends came and we jinked around with it for awhile. It would crank all day just wouldn't fire. Finally I had him wiggle the wire harness on the fenderwell underneath the master cylinder, and it fired up and I drove off

One thing he noticed was a large spark around two black boxes that set next to the master cylinder.

The reason I had him wiggle the harness was because I had the wipers quick working a few years ago, and the wires wore thru where the harness was rubbing one of the hydraulic lines.

I noticed there was alot of corrosion down there.

So I'm here at camp and decided to removed the tape over the harness expecting to find frayed wires and I found nothing!

So I'm prepared for the drive home, what are the two black boxes next to the master cylinder? And is there anything else down in this area that could cause issues?

 

That is where your PCM connects to the rest of the truck. Make sure that the screw that hold it is is tight and that all the connections in there are tight and clean. Also look for signs under the dash on top of the fuse box, sometimes the windsheild leaks and you have water getting on the fusebox and the GEM.

 

"Large spark" makes me think IDM voltage. It found ground and sparked there because it could not get to where it should go. Check the connections of everything wrapped with red tape, including where the 42 pin connector bolts together on top of the driver side valve cover.

'Course, even a 12v spark on these is pretty healthy with those two big batteries behind it...

 

The info's appreciated.
I think I'm going to pull all the connections once I get home and thoroughly go over this thing. So anything wrapped in red are high voltage? How much voltage and when is that voltage live?

Is there a good electrical manual out there to troubleshoot with?
I don't know all these acronyms...IDM, PCM, GEM.

Thanks again!

 

not an electrician, but would think 12v with key on engine off, 14-ish with truck run'n, and 0v with battery cables unhooked.

 

The high voltage from the IDM when it fires the injector is about 115v.

Here's a pic from zxF250 that shows a lot of the sensor names and locations so you can get used to the terrain. Also a general diagram of the HEUI system. Good stuff to look over. The IDM (injector driver module) is located inside the driver side fender kinda behind the F350 badge. Give us the year of your truck and hopefully someone can supply the wiring diagram.

There's a lot of info here if you want to tackle this yourself.

 

Well it shut off again on the way from work tonight! Couldn't get it to fire back up this time however. Towed it to a buddies house...i wasn't happy being towed by a Chebby!

berninF350...thanks for the info you posted. I'm going to start studying it now. I could really use a schematic. Especially one that shows what the wires and connectors do that are located under the master cylinder area.

My truck is a 2002 F250 Lariat, Automatic, 4x4.

 

Well I happen to have some documents for 2002. Attached is a wiring diagram. It's schematic so it doesn't really indicate what's on the fender near the master cylinder, but everything is there if you have the patience. I like it for the little pictures of the sensors, helps ID stuff.

Get a really strong flashlight and you might get lucky and find the black smudge left by that spark.

For intermittent stall I've read to check the IPR to see if it is loose. It is in the valley behind the HPOP, held in with a big tin nut that tends to work loose. And strip easy. The wires to it could be chaffed. Also oil level and CPS are worth looking at. Does the tach move when cranking? I popped a CPS once but otherwise I've not had to diagnose a stall issue.

 

Thanks much. I plotted the wiring diagram out at work on 22x17 paper!

Well the truck fired up this evening and i got about 3 miles from home and it shut down again. I had a new cam position sensor...installed it, didnt help.

One thing I've noticed is if you wait an hour or two it'll start back up and run. The weather's been unusally warm lately...maybe the additonal heat is having an efffect.

 

I pulled the fuel filter out today and it was full of black pieces and gunk! Pulled the heat element out and cleaned out the bowl and put it together with a new filter. Could this cause the engine to shut down? Not in the sense that fuel can no longer move thru the filter...but restricting flow enough that it triggers a sensor reading low fuel pressure and shutting off the engine? One thing I noticed last time it shut off was there was no fuel coming out when I tried to drain the filter bowl.

Also, last time I got fuel it was at a place I don't normally get fuel, and it was shut down for a few years and reopened recently...also don't think they sell alot of diesel.

 

Might be some pretty old diesel ya got there. How is it running now? If the fuel filter was seriously dirty your in-tank filters may be gunked up too. Lack of fuel is an effective way to make a truck not run, but it doesn't explain the big spark by the MC. Search on Hutch and Harpoon mods and/or in tank mods for directions to fix what Ford did wrong down there.

 

Update on this thing. Did the hutch/harpoon mods. The tank was practically spotless but the mixing chamber filters had some crud in them. i installed a 100micron filter before the new electric pump.

Was running fine until this afternoon I was in town and it wouldn't start. Waited about 10 minutes and it started and made it home.

I guess I'll get into the HPOP next? Maybe clean the IPR? How high of an oil level should the HPOP have? It's about level with the gasket surface.

I've been reading about testers to check things like IPR percentage, blahblahblah...what' is a good tester to invest in and what do I look for?