How to rewire FSS/Injection Pump

[84IDI-BERTHA]

EDIT: My apologies, the truck is a 1984 F250 6.9L Has a turbo, but as far as I know that doesn't affect the stuff on the front of the motor.



How is everyone?? I haven't been on here in a while, as I was deployed again and will be leaving in a few months for another, hoping all is well while I am gone!

I have been doing research the entire day attempting to figure out a solution and only got some good ideas, but no solid fix. (might be the hours of staring at the computer is frying my brain)

I went to start my truck today and noticed that I have two issues. My first issue is that my High Idle Solenoid, there are the two wires that plug into the engine temperature gauge (not sure if that is the correct wording) when the vehicle is running it appears the temp gauge in the motor is "smoking" with a distinct smell to it. It is not either of the connectors for the wires, but the entire piece in the motor.....anyone ever hear of this type of situation???



The second, and much more important at the moment, problem is that my FSS keeps melting wires. I have been looking into this issue on oilburners, and a few other forums hoping someone had an exact fix or something along those lines.

What is happening: There are two red w/white stripe wires coming off the plug for the FSS, and feed into a connector on the passenger fender area. (I believe it is an 8 wire) On the opposite side of the connecter is a small 16ga wire that disappears into the mass of wires heading to the cab of the truck. This wire burned up one day, about 8in of it, smoking and charred to a crisp. I pulled out the little bullet connector and soldered a new wire onto it and used a butt connector to attach the new section to the length of old going to the cab........ Today it completely melted, the sleeve of the wire fell off.....replaced it with 16ga wire again and it melted a second time, progressively smoking and getting hotter until it just fell apart. I pulled the wire out, and the engine cranks, but does not fire off ---- plugged the wire in and the engine fires right up and the wire gets extremely hot to the touch. So I narrowed it down to the FSS being the issue.


I APOLOGIZE FOR SUCH A LONG IN DEPTH DESCRIPTION, JUST HOPING IT HELPS TRIGGER SOMEONE'S THOUGHTS AND IT HELPS ME OUT. HAHA

What I think would fix it: I read on multiple threads, that you can just run a wire from the FSS with a fusible link, to the fuse box. Is this true?? The other option I saw is that someone claimed the FSS can be hooked up to the Glow Plug Relay, but my plugs are one a manual switch. Will this be an issue if I try to use my GP Relay for my FSS power feed?? IF SO, what is a good fix for this problem that will NOT keep melting my wires.

Thank you for any help, I will check this as often as I can


-Brandon

 

[Matrix37495]

If you run a temporary wire from the battery to the FSS does it work properly or start melting the wire? It should be fairly low amp draw.

The wire that goes to the FSS has another wire that comes out of the connector and goes down to the coolant temp switch that controls the cold idle advance and idle up solenoids. This could be internally shorted. Try unplugging it and see if your problems persist. (The two wire plug you mentioned. Down behind the alt and thermostat housing) An internal short would also explain the smoking and smell.

When mine was repeatedly blowing the fuse link it was because the wire that runs my fuel heater was laying loose in the intake area and shorting to bolts at random. This gets power from the same wire as the FSS. I just taped up the wire and been good ever since. The fuel heater is the fat part if the fuel line leading up to the filter head (if so equipped). The connector is round with a single wire.

That gives you a couple things to test. I'm leaning towards a shorted temp switch unless it's already been unplugged...

 

[84IDI-BERTHA]

Thanks for the reply Martrix. I will try running a temporary direct wire when I get home in a few hours, hopefully it could fix it?? I will let you know.

The Temp Switch I figured was a goner, so I unplugged the clip going to the idle solenoid/cold advance solenoid. Once unplugged, it stopped smoking and smelling, but the wire going to the FSS still melted. The two wires running from the FSS to the harness are a direct route, both in the same connector hole and everything. I will recheck it when I get home to make sure I am remembering correctly.



If my wire doesn't melt, with a direct line to the FSS.....Am I able to just hard wire it to the fuse box or battery?? Or do I have to trace that back to it's exact hook up location (if that makes sense)

WILL REPORT WHEN HOME

 

[franklin2]

This wire is hot when the key is in run, and is a popular one to tie add-ons to under the hood. You don't have a electric fuel pump tied into it somewhere do you?

 

[84IDI-BERTHA]

no sir, no electric pump that I am aware of. If it's hot when the key is on, can I just find a fuse with the same power supply and tap into it?

 

[Matrix37495]

Yes, but make sure its always hot in run and start... Not all of the key on hot wires are still hot in the start position.

 

[84IDI-BERTHA]

Awesome. Thanks guys, I will still give you an update kn the direct line to the FSS. Trying to type on my phone now while my wife chatters in my ear....hahaha

EDIT: What gauge wire should I use? As well as what size fuse?? I am good at running and splicing wire, but have no idea what fuse sizes etc etc to use.

 

[84IDI-BERTHA]

Well I just got home late, so sorry for the hold up guys. I will try to look at the truck here in a bit, once I find my work light.....wonder where it went?!

Does anyone have any idea what gauge wire I need to run to the fuse box, and what size fuse I need to use to power my FSS?? It looks like 10 + 12 gauge from the FSS to the connector, and 16ga from the connector to the cab........ Can I just Splice the two fat wires from the connector to a 16ga (acting like the connector) and run it that way??? and just throw a nice fat fuse on it. haha

 

[franklin2]

Go ahead and run 14 if you have it, but 16 should be large enough. Put a 10 amp fuse in the line if you run 16, you can put a 15 amp fuse in the line if you run 14.

 

[84IDI-BERTHA]

You are the man franklin. That is what I needed!

Matrix --- Got preoccupied today with house cleaning and shopping stuff So tomorrow afternoon after my other job is done, I will try your idea of the line to the FSS from the battery. hopefully it won't fry the thing and I can just run the wire like franklin said. Then I can re-fix my glow plugs and attempt to fix my leaky return line. YAY

 

[84IDI-BERTHA]

I put a line from the battery to the FSS, and the truck fired up without fryin the wire......so i wired the thing up to a fuse in the cab, and all of a sudden, it won't stop....i shut off the truck and it continues to run, so I had to pull the fuse out to kill the truck. how the hell do i fix that now?? how would i run a switch to the cab?

 

[Fordsandguns]

Yep, you need to wire a switch into that jumper to be able to turn off the engine. You literally by-passed the ignition switch by running the new wire.

 

[Wyreth]

What Fordsandguns said.

The FSS is what literally starts and stops your engine. A diesel needs nothing but fuel to run. So until FSS is turned off, and the fuel to the engine is shut off, it will run. That was what Matrix was talking about when he said to find a circuit that was hot when the key was in both "on and start" because the FSS will need to be on while the starter is spinning, and when the key is just on. The "start" position disables most of the switched circuits on your truck, so that nothing is taking power away from the starter.

You can either wire a switch inline as Fordsandguns suggested, you can find the short in your FSS circuit, or you can find another circuit from the fusebox to power the FSS that is hot in both "on" and "start" positions. Any of those options will fix your problem.

 

[84IDI-BERTHA]

You all rock. Thanks for the help guys!! It is easier for me to read this and go and do it to learn and understand what is going on. Need to be hands on, so sorry that it takes me a little bit. haha.

 

[Fordsandguns]

Sorry, I should have explained it better as Wyreth did but I was tired when I posted. Not to mention that I tend to have a hard time putting my thoughts into words in an order that they can be easily understood.
I guess my thoughts are jumbled and I'm just used to it!