Hi all. Searched the threads. Found a ton of threads that helped me start eliminating some of the possible issues but......... here is the rundown and hoping you guys could point me in the right direction.

2000 F350 SuperDuty 7.3L Diesel 4WD Crew

I was driving today, and coasting up to a light, when the truck just cut out. Turned over but will not start so got the truck towed home (sucks but it's home).

Started working on it. Since it turns over fine, figured likely fuel issue so pulled filter and turned over while dad checked the fuel in the filter bowl...... no fuel coming in.

Checked for voltage at pump, no voltage at pump. Checked voltage at fuse, no voltage and fuse checks out good (has continuity with meter).

Read a ton on the posts and seemed like it could be the relay so next, changed Fuel Pump Relay out behind the radio, and no difference - still will not start. Fuel pump relay does not click or anything like I read it should.

I am at a loss now. If relay is good, fuse is good why am I not getting 12v at pump/fuse and why is the relay not actuating?

One other thing I noticed that is weird is that usually the "Wait to Start" light comes on when I turn the key to the on position before trying to start it but now it is not coming on at all. Not sure that has anything to do with it but thought maybe it did so figured I better get all the info on here.

I am definitely open to suggestions on what it could be and thanks in advance for any help.

 

Time to check all the fuses, starting with the PCM fuse. No WTS light usually means no PCM.

You are one lucky dog to be living in St Augustine

 

Look in the fuse box under the hood. Look at the large fuses and the small ones. Mine blew the large one but most people blow fuse 19 i think (may be wrong about the number). If its bad, disconnect the plug on the back of the fuel filter housing. The fuel bowl heater will blow and cause the fuse that powers the pcm to blow.

 

BigB56, yes. I love living in St. Augustine. Heading off to school at end of August to FAU in Boca Raton...... wondering how my superduty will fit in there LMAO.......

Thank you and CarltonWebb for the fuse suggestions. Somewhere on here after I posted I came across a post that had nothing to do with fuel but it said try #24 or #27 as they could both affect PCM........ sure enough #24 was out.

I can't thank you both and all the others enough..... going to head to AutoZone in the AM and pick up a couple. Will see if that works.

Just wondering, is that a common problem for one of those to go out? If so maybe I will order a gross of them online LOL..

Have a great night both of you and thank you again!!!!

 

Yes it's common that's how we know about it. Best bet is to do as he said and unplug the fuel bowl heater and wrap it up with electrical tape replace the fuse and never worry a out it again. Good luck.

 

Hi John2001.

thank you for the information. The fuel bowl heater was disconnected already but I still keeping blowing the 20A #24 fuse. Put in 3 new fuses and each time, the fuse popped immediately each time.

If the fuel bowl heater is disconnected already, there must be something else causing it but I can't figure out what else might cause that fuse to keep popping.

Will take any suggestions........ and thank you all again.

 

Hi everyone.

So, here is an update and I am still searching for an answer.

Here is what I do know (both the good and the bad):

Truck just cut out yesterday. Turns over well like it wants to start but no fuel. Thought initially a fuel problem.

Wasn't getting voltage to pump so figured it was a relay. Changed fuel pump relay in dash behind radio. Didn't help. Still same so the folks on here guided me toward fuses, so go to fuse box and #24 is out.

Bought some new 20A maxi-fuses but didn't help. Fuse 24 in underhood fuse/power distribution box keeps popping immediately when I turn the key to the on position.

You guys helped me by getting me to fuel heater at filter but, fuel heater at the filter was already disconnected when the problem started, so not the fuel heater (or at least that seems to be the case).

Friend suggested glow plug relay. Disconnected glow plug relay, thinking that might be the problem. With glow plug relay completely disconnected, fuse popped when the key was turned to on, eliminating the glow plug relay as the culprit I would think.

I am running out of things to check and just can't figure it out. Any help would be great.

How do I check to see if the PCM is bad? Could that be causing this problem?

If that doesn't help, how would I check for a possible short to ground and where is the most likely place to look?

I welcome all help. My first F350 SuperDuty so I am a novice. Really excited to own it. Drove it for a week and it ran GREAT the entire time until this

In case anyone needs, my dad helped me fix the overhead console and I would be happy to trade notes on how we did that....... a 32 cent resistor from Radio Shack LOL.

 

I would just find out what that fuse feeds and start looking through wire loom for a short. You could also do a continuity tests on each side of the maxi fuse. If its grounded out it could give you the direction to start chasing wires in....

 

Hi and thank you for the idea to check the continuity.

On one side of the fuse, I am good. On the other side, I get a continuity to ground. None of the other fuses do that so I am guessing I have a wire that is shorting to ground somewhere. Anyone know where I can get a diagram showing the fusebox wiring out to the vehicle? That would help me narrow it down.

 

After the fuse 24, it goes thru contacts of pcm relay, feeds small wire gpr, small wire aih relay, brake psi switch on master cylinder ( alot of trouble with these-especially if you have not had recall done), to coil side of Fuel pump relay (other side of coil is grounded by pcm pin 94), to transmission to power solenoids on pins 1 & 12. and it provides 12 v to pins 71 and 97 of pcm. It also provides power to IPR solenoid on hpop.All the wires are rd except the two at transmission ( red w/ yellow stripe). The Fuel heater is not on this fuse.
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Check the brake psi switch for fluid in the connector and also look at the harness for the small wires on the gpr and AIH to see if there is a rubbed place.. Swap pcm relay with blower relay and see if anything changes. Beyond that you will have to eliminate the other possibilities.

 

Okay, so using all of your advice, I started looking where the #24 fuse wire left and where it went. Have some pics but not sure how to post.

Basically what I discovered is the power wire (red wire) from the back of the PCM Power Relay (#30) was going to ground. Started messing with it and tracing and as CarltonWebb explained, I discovered it went through the loom, down under the airbox, across the engine and ended at the 2 relays on the other side of the fuel bowl.

Using my continuity meter I know that those pair of relays with the 4 wires total all connect to that side of the PCM Power Relay.

I also found it was going to ground, that was until after I started messing with the wires and somehow, must have cleared the ground situation. Not trusting that though. Would like to run new wire from the PCM power relay to the GPR and other relay.

Not sure if I would be cutting anything out of the loop by doing that though so will trace the wire tomorrow and see what I find, where it rubbed and all. Never realized how much work that would be to hunt down a short....... but worth it in the end.

Have pictures of what I have and would love to post them but not sure how so will work on that in case anyone else ends up in the same boat as I am now.

Thanks for all your help again!!!

 

The two relays at the fuel bowl are these:

Closest to the front of the engine is the AIH relay (air intake heater). That one hardly gets used and only gets a ground on the other small wire from the pcm to activate under certain conditions with the park brake applied. Most people take the air intake heater element out of the turbo and disconnect the relay.

The one farthest back is the GPR (glow plug relay). It needs to be there and working. It gets its ground from the pcm just about every time truck is cranked.

Look really hard at that loom as it could be anywhere in it but prob pretty small. Make sure u look at the ipr coil (inj psi regulator coil) one too as it should be in it as well.

I am not sure where the splice is to feed the other components.

To post pics, make a public photobucket album at photobucket.com and post the link in a post.
.

 

Hi All.

I want to thank everyone for all the help. Been tracing wires. Figured I would start with wires that didn't have wire loom figuring that it would be a wire that was exposed that would rub. Makes sense right?

Nope. It was the first thing I checked but covered by a wire loom. The guy I bought the truck from had disconnected the fuel bowl heater wire. He didn't ziptie it to anything, just let it hang. Turns out, the wire loom had slipped over a spot that was worn through on one of the wires for that which is why I didn't find it.

Only when I finally pulled all the looms off and traced the wires I found a sever chaffing on that wire. Have now fixed the wire up, tied it off a solid point so it will not swing and chaffe any more, and I am up and running.

Love the Liquid Electrical Tape!!! Painted it on the bare spot on the wire and good to go yahooo!!!!

But wow, what a job wiring seems to be on this truck LOL.

Thank you again to all of you.

 

Great job with the troubleshooting! Wiring is one of the most intimidating things to try and fix on these newer cars. Reps sent!

 

Great job! That was a lot of work to chase it down by following wire, but catching an intermittent short is a real achievement.