I FIX ONE THING, ANOTHER BREAKS... HELP

[92 dizzel]

Hey guys, I use my truck to haul water for my house and livestock, any help is greatly appreciated as we have a massive heat wave coming and I'm running out of water...

So we pulled the tank and replaced the shower head pickup tube. Great, engine is running ok. The timing seemed off again so we advanced it.

Went to the feed store, loaded hay. Started truck and it dies. It has power, starter will turn over, but no glow plugs, fuel is dead. My electric fuel pump relay is wired to the old fuel heater.

I hear a click and I'm able to start it and drive home. We park, shut it down, start it again and she dies. Turns out the #17 maxi fuse keeps popping, and at some point that fuse was replaced with a breaker that will come back on. Every time we start it, it immediately dies due to the fuse popping.

I have tried to track down any bad wires. Even replaced the glow plug relay. Funny thing is that my glow plug relay will work if I run a hot lead to the fuel shut off on the IP. I can use the hot lead to get the truck running...

Help??

 

[riphip]

Your fuel pump should be in circuit with injection pump FSS. Your fuel heater is probably shorting out. Disconnect the fuel heater altogether & see if circuit breaker kicks with just the e pump on it.

 

[franklin2]

#17 maxi fuse? What year is this truck?

 

[92 dizzel]

I did try disconnecting the fuel heater line, also tried disconnecting my electric fuel pump, the AC line and the tach sensor to the IP. The only thing I didn't try was the alternator.

Now I have no power to the glow pug relay and the Fuel shut off, and the breaker is good.

1992 f350 7.3 idi no turbo

 

[92 dizzel]

Let me be more specific.... there is power to the glow plug relay but no power coming out of it. Tried a brand new relay, same outcome.

I'll go out and try a couple other things now that it's cooling off a little

 

[92 dizzel]

#17 maxi fuse? What year is this truck?

I may be calling it wrong... it's the 6th "giant" fuse when counting from the passenger side to drivers side.

 

[92 dizzel]

It's the weirdest thing. When it first happened the fuse would blow and I would have no power to the glow plugs, the FSS on the IP or the fuel heater. Now I turn the key and I have power to the fuel heater but not the rest, and the fuse won't blow. I can hot wire the FSS and the glow plug relay will come to life and I can run the truck, thankfully, because I need water.

All fuses and relays in the fuse boxes check out.

I can overcome just about anything, but give me a wiring issue and I'm dead in the water.

 

[franklin2]

Here's your wiring. Not much to it. You are correct, there is that maxi fuse "K" 20 amp that is feeding this circuit. It's all mostly on top of the engine, except any added wiring. I think you said there was a fuel pump added? When you power the IP directly, you are backfeeding this circuit. How much current does your electric fuel pump need? Is that taking you over the top (20 amps). You could possibly hot wire the pump temporarily and then see if the maxi fuse holds.

 

[92 dizzel]

Here's your wiring. Not much to it. You are correct, there is that maxi fuse "K" 20 amp that is feeding this circuit. It's all mostly on top of the engine, except any added wiring. I think you said there was a fuel pump added? When you power the IP directly, you are backfeeding this circuit. How much current does your electric fuel pump need? Is that taking you over the top (20 amps). You could possibly hot wire the pump temporarily and then see if the maxi fuse holds.

Thanks for the diagram.

The duralift fuel pump is hot wired to the battery, with a relay wired to the old fuel heater. That actually works now. The fuse (breaker) no longer pops, but my glow plugs and Fuel shutoff on the IP do not, so whatever was popping the fuse has now completely burned out instead of shorting out. That's why I can now back feed it by hot wiring the FSS on the IP.

Guess I have to rip apart all the harness and find where it shorted and burned...

 

[92 dizzel]

Actually, I'm thinking about this all wrong...

There is a hot lead to the glow plug relay, and another lead that is relayed to the ignition. If the glow plug relay is not coming on, then I need to track down the relayed ignition lead... and find out where it shorted out.

Possibly the ignition switch...

 

[franklin2]

Actually, I'm thinking about this all wrong...

There is a hot lead to the glow plug relay, and another lead that is relayed to the ignition. If the glow plug relay is not coming on, then I need to track down the relayed ignition lead... and find out where it shorted out.

Possibly the ignition switch...

Easy to check this. Take a testlight and see if you have power at the maxi fuse with the key turned to run. If you don't, then it's going to be upstream going to the ignition switch like you said.

 

[franklin2]

Here's another diagram for a 1992 diesel. This is the ignition switch wiring. I am thinking all the way to the left side of the diagram there is a red/lightgreen with a "K" annunciation. I am thinking that is what feeds maxi fuse "K" but let me look some more.

 

[92 dizzel]

Ya all fuses check out and have power.

We took apart the steering column to start tracking down where it's dead. I did find the wire disconnected that connects to the side of the ignition tumbler. Fixed it. No change. It may have caused the original short and thus fried something else, I don't know

 

[franklin2]

Found it. These look like the "real" Ford diagrams, not some generic redo like the first diagram I posted. You can see in this diagram there are two Maxi fuses, K and U. K feeds the glowplug system, U feeds the fuel heater, the special alternator if you have that, and the relay for the computer system if you have a E4OD.

 

[franklin2]

Ya all fuses check out and have power.

We took apart the steering column to start tracking down where it's dead. I did find the wire disconnected that connects to the side of the ignition tumbler. Fixed it. No change. It may have caused the original short and thus fried something else, I don't know

So if the maxi fuses have power, then the problem is going to be downstream from them, not up in the ignition switch area.