F1 Fuse keeps blowing Advice Needed

[metromark]

The F1 15 amp fuse keeps blowingin in my 96 geo metro.

When it blows the car will die. As soon as i replace the fuse the car will start again.

Intermittently blows fuse again.

Somthing with the Fuel Injection System???

Any help you can offer would be great

[geozukigti]

There's a wiring harness that goes between the engine and engine computer. It runs through the firewall, then to the ecu. You'll notice that right next to the brake booster, there's a bracket for the wiring harness to attach to. This was a "fix" for that problem you're having. When the engine moves, so does the wiring harness. eventually, the movement will wear the wires bare on the inside of the harness, and they will short. But, rather than blowing the ECU, it just pops that fuse. So, the problem is 99% that wiring harness. Make sure it's properly secured to the bracket that comes off the brake booster. If it is, and it's still popping that fuse, the wiring harness needs to be taken apart, checked for bare wires, and re-taped. Good luck, it's a real pain in the a$$

[Mike_Van]

A pain in the a$$, indeed.

This situation occurred with my '96 1.0 5-speed last evening.
I was driving and I simply stalled out. Re-start failed due to no juice getting to the FI circuit. The 15-amp FI fuse I replaced would blow when juice ran through the circuit.

I unwrapped the wiring harness to see if I could ID the offending wire, amongst the dozens that compose the harness.
What I did see were a few wires that were spliced with *duct tape*, rather than elec. tape (this cannot possibly be OEM).
I never saw a bare one.

Does anyone know if these came from the factory with inline wire splices (two wires from the engine bay spliced into a single wire that goes through the firewall)?

I do not know what I did, other than moving a few wires from their original position, but now the fuse no longer blows.
Not a satisfactory fix, at all.

Is the arcing something I could see better in the dark (as one would with a bad spark-plug wire)?

[geozukigti]

you'll never see the arc. The factory did make splices in the power lines mainly. They do not usually cause problems tho.

[Mike_Van]

Well, it happened again, so this time I took it to my favorite shop.

The kind folks there found the culprit (would have taken me forever).
The FI fuse was blowing because the ECU (computer) was protecting itself, which jives with what geozukigti wrote. Two wires going to/from the idle-control stabilizer (behind the engine block) from the ECU were worn underneath their protective shield (tape) and shorting-out the circuit.

The wear was likely the result of the PO having a thermostat replacement done, and the person who did it not re-attaching the wiring harness via the appropriate metal retention-clip. Instead, s/he attached it to a part of the engine (vibrates quite a bit).

Before bringing it to the shop, all attempts I made to fix the issue like I managed to do last time (trying to reposition the fat wiring harness as it comes through the firewall) failed.