IP FSS fuse rating

[Scratcher]

Thankyou everyone who has jumped in to help here. It's much appreciated! So I started tracing and without ripping into the woven casing and outer plastic casing its pretty obvious, at least initially, that there are no bare wires touching the frame or the block.

Can someone tell me why there are two wires spliced into one and being fed by, what was the fusible link? The same two wires run to the terminal that plugs onto the FSS. Why two wires running from one?

 

[Scratcher]

Okay. I separated the two wires that run to the FSS and it's the red wire with the black stripe that is shorting. I still don't know why there is another wire spliced to that at both ends. (one at where the fusible link was, and the other at the terminal that attaches to the FSS) I separated these two wires and tested each separately and determined the red with black stripe to be the culprit. Since everything is encased in the woven protective material and inside the outer plastic sheathing I'm not seeing any visible signs of a short. Only thing i can think of is that there are two worn wires that are broken in the same place and touching each other?
My thoughts now are to cap the offending wire at both ends and isolate it. Then run a new wire from the fuse link to the FSS?

 

[franklin2]

There are many splices in that wire. That one fusible link and wire split off to feed;

the fuel heater

the glowplug controller which then feeds the glowplug solenoid (purple wire)

the fuel shut-off solenoid

the engine temperature switch which then feeds

the cold idle solenoid

the cold advance solenoid

A problem anywhere in these circuits can blow a fuse or fusible link.

 

[Jesus Freak]

Start chasing the wire. The fact that it blows at different intervals means it's a wire that the casing has worn through and is grounding out on the frame.
Start at one end of the circuit (I suggest the pump) and work backwards. The circuit is very simple. Goes from the IP to a big connector on the passenger side valve cover, then from there it goes to a split, then the fusible link.

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I wish it was as easy as those diagrams make it look. Where's @Selahdoor, he would apply extreme logic to this discussion.

 

[Scratcher]

Okay, I decided to stop dicking around with it and just pulled the whole harness out. It would always be niggling me that something was wrong in there. Even if I bypassed it, the potential for a catastrophe would probably be very real.
I only have a small logging operation to get done for our winter firewood and then the truck gets parked for the winter anyway. So right now I have a single wire rigged up to the FSS. It still starts without plugs since I have have just installed new batteries and have a gear reduction starter. A little burst of Ether might be necessary. I know I won't have a few gauges but this was a jasper rebuild and it only has 30k on it.

I guess I will be learning all about my glow plug harness now once I start tearing into it!

 

[franklin2]

Your original Ford gauges in the cluster are not working now? You are not missing much. You should have aftermarket gauges on it anyway.

 

[hacked89]

Your original Ford gauges in the cluster are not working now? You are not missing much. You should have aftermarket gauges on it anyway.

Agreed. I would recommend cutting out everything except the accessories on the truck and then wiring and making your own harness from there. That’s what I’m in the process of. Only thing I cut out from the factory that I’m adding back in was the tachometer because i haven’t liked what I’ve seen in aftermarket. I just got 8 gauges and the tachometer I swapped out for ambient air so I can figure out starting ambient temp to glow plug timing.

 

[Scratcher]

It looked more daunting until after I took it out and got into it. As far as I can tell the problem was with the old cap from the glow plug controller (I went manual a few years ago). Anyway I cut out the old controller and I assume nothing was being jumped off of that for anything else?

The rest of the wiring, including the thicker glow plug feeds are in good condition. No cracks or splits. So I'm thinking they can stay as is.

As to aftermarket gauges. I don't have a lot of money to spend and I have no idea what I'm actually doing here. I would appreciate some guidance.

I'm actually falling in love with my old girl again now that she has demanded my attention!

 

[franklin2]

A cheap set of mechanical gauges from the local autoparts store is better than the factory gauges. I usually only get 5 or 6 years out of the cheap mechanical temp gauges, but at least they are accurate when they work and have actual numbers on them. The original Ford gauges are ridiculous. And I don't think they ever changed, my 2009 at work still has gauges with no numbers on them.

 

[Nero]

Most vehicles won't have numbers, and even then, they're mostly not accurate. Even Vw's use a four wire sensor, one loop goes to the cluster as a 'dummy gauge' which has numbers on it, and the other loop goes to the computer and lists the actual coolant temp. The gauge reads 180 way too early.
I agree aftermarket gauges are good, but straight up axing the cluster? Meh I prefer keeping it stock.

 

[franklin2]

The cluster can set there and tell me the speed and how much fuel I have. I will have aftermarket gauges hanging under the dash for everything else. I am not picky, I just want good reliable info.

 

[Scratcher]

Started another thread since we have moved from fuse rating to gauges!

Gauges Guidance

Thought I should start another thread since the FSS fuse rating thread has gone way OT lol. So, as you can tell from my sig I have a stock truck with no bell's and whistles. I no longer use it for work because I took an nice easy indoor job as a facilities director in a local school...

www.oilburners.net

 

[Black dawg]

Most likely is the temperature switch that switches power to the cold advance and fast idle.

I have seen this enough times, that I always put a fuse right before that switch on my own trucks.