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Fuel bowl wire pictures

23K views 12 replies 4 participants last post by  Dundeediesel 
#1 ·
Does anyone have a picture of the fuel bowl heater wire that is the common suspect when the 20 maxifuse (under the hood) blows? I have it narrowed down to either the fuel bowl heater being shorted or the glow plug solenoid. I think those two components are on the same fuse. ..?
Here's my issue: I turn the key to the start position. 20 amp maxifuse blows and the wait to start light doesn't come on.
I'm new to this blog, and new to owning a powerstroke but so far I love it and appreciate the help and advice I've read here.

I have a 1997 F350 5spd manual with about 200k on it. It ran fine until it died... :) Now it does this.

Thanks in advance,
Jon
 
#2 ·
Fuse #22 is a 30 amp maxifuse. Is this the one you're blowing?

The glow plug solenoid coil is on the same circuit as the heater wire. This coil is grounded by the PCM to turn on the GPR, and the coil normally should pull less than an amp. The PCM power relay coil is also on the same circuit, also pulls less than an amp.

The fuel heater wire is red/light green on my '94 and I'm pretty sure its the same color on yours. Look for that color wire and unplug it and tape it so it doesn't short to anything. Also check to make sure it isn't shorted to ground under the fuel bowl or anywhere it might rub.
 
#3 ·
Yep it's the #22. I don't have the right owners manual and the CD manual I bought off eBay says it supposed to be 20amp. I have no idea. I have been reading the other previous posts regarding this issue and narrowed it down to either the GPR or the Fuel bowl heater. What do you think? Thanks for responding.

Jon
 
#4 ·
Fuel bowl heater and it is indeed 30 amp, just unplug the wire and you should be OK...
 
#5 ·
I unplugged the red w/light green stripe wire and it still blows the fuse. I don't have a decent ohm/amp meter so I use a test light in the fuse spot. If it lights up then it's "bad" right? Here are the updated symptoms: I turn the truck on (i have 12 volts on the batteries) the glow light doesn't come on and the truck doesn't turn over.
 
#6 ·
You've possibly got a bare spot in the wiring harness which is shorting to ground.

You need an ohmeter, the test light only tells you the presence of 12 volts. An ohmeter will tell you if you have a short to ground--it sounds like you have a bare spot in the wire to the fuel heater. This wire goes under the fuel bowl so its susceptible to chafing.

Here's a test procedure if you had an ohmeter. Ohmeters can be had for jsut a few bucks at Harbor Freight or maybe even Walmart, you don't need an expensive one, we're just looking for continuity.

Disconnect both negative posts of the batteries.

Pull out the PCM relay, and take the red/light green wire off the GPR. Remove the #22 maxifuse. Now with the ohmeter you would measure to see if there's any resistance between the red/green wire that you just took off the GPR and ground. Zero resistance=a short to ground.
 
#7 ·
The truck had some issues when I bought it. (Wouldn't start) The tow truck driver was a Powerstroke fan and showed me the harness for the fuel heater, (and three other components?) was totally shreddred. I bought a new harness in July and installed it. So I hope it's not the harness. Where is the PCM relay?

I have some Christmas cash and have been wanting a ohmmeter. Napa has a good sale so I will pick one up.

I'll let you know what I find.

Jon
 
#8 ·
The PCM relay is one of the four or five relays in the power distribution box, dunno off the top of my head what number it is. They're all the same, when you want to do the test you could easily just pull them all...

Have you messed with the glow plug relay? Check where the red/light green wire goes to the glow plug relay, perhaps its worn through or touching a ground there.
 
#10 ·
I traced the red/light green wire to the GPR and sure enough it's grounded out. Luckily its not in the wiring harness I bought a few months ago. Unfortunately that means it's shorting out somewhere else between the plug on the passenger side of the fuel bowl in the wire loom going to the GPR. I disconnected it from the GPR and the fuel bowl and the fuse stopped blowing. The truck still won't start. I suspect weak batteries. I have the engine warmer plugged in for the night and also have the batteries on a 2amp trickle charger. I'll try again in the morning. I did notice quite a bit of smoke coming from the exhaust side of the turbo. Any ideas what that means?
 
#11 ·
Now we're making progress! Here's how the GPR is wired: The red/light green supplies 12 volt power at all times (with the key on) through Fuse #22. It goes to one side of the coil on the relay. (The coil is basically an electromagnet; when it's energized, the magnet pulls on a big set of contacts and closes--or opens--the main circuit). To complete the circuit and energize the coil, the other wire from the coil (pink/orange on mine) goes to the truck's PCM (the computer). When the truck is started the PCM internally grounds the pink/orange wire, which completes the circuit through the coil, and pulls in the contacts that switch on the glow plugs.

So the short to ground would not be in the pink/orange wire, since basically that would just complete the circuit just like the PCM does. Either the GPR has shorted internally--I've never seen a coil do that but theoretically maybe its possible, or somehow the red/light green wire was grounded right at the GPR. With an ohmeter, you would now disconnect the Pink/Orange wire and check to see if you had zero resistance (a short) between the two small terminals on the GPR and ground. There should be infinite resistance between the small terminals and the case ground. Between the small terminals themselves there should be a small but measurable resistance, maybe a few hundred ohms. A reasonably sensitive ohmeter would be required to measure the coil resistance. CAUTION: if the batteries are still connected, the big black/orange wire on the GPR is hot, don't let your meter probe hit it, it may fry your meter if set to ohms.

As far as the exhaust, where exactly is it coming from? Perhaps there's a leak somewhere either in the up-pipes (quite possible) or the turbo collector gasket, or the EBPV or downpipe is leaking. But until the truck is running, that's not critical.
 
#12 ·
Here's the GPR schematic
 

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#13 ·
I learn from my own mistakes:
I disconnected the fuel heater from the side of the fuel bowl and also disconnected the same colored wire from the GPR. Thinking that would be neccessary. That was not. And in fact stopped the relay from working. After several trial and error moves including going to Napa and buying a GPR-109 I thought maybe the red/green wire on the GPR was important. I reconnected the wire and the vehicle began cranking. I noticed that my batteries were not giving enough volts. So I took them off and had them checked and sure enough they were bad. So I bought two new ones and I now have a running truck. Thanks to everybody that gave advice. This is a great website community!!

Jon
 
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