Fuel INj fuse won't stay intact

[wytbishop]

So I got the engine back in the beast on Saturday morning...had a few minor issues, but got everything going ok. I drove the car Saturday night and then this morning (Sunday) I was on my way to my friend's place to finish up some stuff and about half way there it just dies. Wierd thing is the "Charge" light comes on so I immediately suspect that the alternator has fried again. I go to Canadian Tire, with my receipt and get it tested and sure enough they say it's no good and they warranty it for me.

I go swap the new alt in and no change. Quick check says there's still no spark...must be the distributor I figure. So I give it a look through and hey!!! a broken wire on my 3 pin plug. So I fix it. No change. Charge light is still on and no spark. I still feel like it must be the distributor so I go to pick n pull and there's a 92' disty...so I grab it run home, stick in on and no change.

So I keep looking and I find that the Fuel Inj fuse is burnt. HAHA!!!!! I don't have a spare so I take the cooling fan fuse and put it in the fuel inj slot, turn the engine over... no change...and the fuse is burnt again.

So I stick one of the other fuses in the Fuel Inj slot and just turn the key on...no cranking. Charge light comes on and the fuse is burnt.

So I think i know the only way that this can happen, but I would like to hear someone else say it so that I know I'm not chasing a wild goose.

Pictures...sort of...





Searching through the a annals of time I have found one other member who found the problem I think I'm looking at...like 6 years ago. It seems so unlikely to me, but it has happened before so I guess it could be.

please offer your input.

[Nd4SpdSe]

It doesn't necessarilly mean there's a short, but that's easy to test with a multimeter and check for continuity to ground.

It could also very well be something that's drawing too much current, that's usually the sign of something failing. You've also got the heating element of the 02 sensors in that circuit too, they/one could be drawing too much power. Obviously it would be nice to have an amp meter to test that, and the ones on multimeters wouldn't be enough, usually only 10amp max. I've always wanted a clamp on amp meter.

Unplug harnesses, try a fire up with no 02's (maybe even no IAC cause that's easy to unplug), easy test to isolate a few things while the motor should still fire up if the fuse doesn't blow. Considering you have a ZE, not sure on the state of your EGR system and if you're using it.

[Ryan]

The white/red wire is the power to many many system components. Most of your sensors and outputs.

Aside from chasing it down with a multimeter, component by component (using the diagram to narrow it down faster), you could unplug mostly everything in your engine bay, turn key to ON, and then start plugging stuff in until it blows.

I would first suspect the regulator though... most of the stuff I can think of isn't likely to fail closed.

[Nd4SpdSe]

I would first suspect the regulator though... most of the stuff I can think of isn't likely to fail closed.

Shoot, looked at the second diagram quickly this morning, didn't see the first. That's definitely a good call. With a strong battery, you can unplug the connector on the alt to see if the fuse blows. Question is, does it blow when the car is in ON, or only when cranked/running?

[wytbishop]

Fuse blows as soon as the key is switched on.

Here's my question Ryan. If I unplug everything in the engine compartment and a bare wire is grounding out to the frame or body...it will still be grounded out whether it's plugged in or not won't it?

I think what happened is when I was paining in the engine compartment I had to partially disassemble the fuse box and move the harness around a lot and I'm sure a couple of wires cracked or are rubbing against something and shorting. I will unwrap the harness and open up the fuse box but if something obvioius doesn't jump out at me I'm not sure how I'll identify the faulty wire. It could literally be anywhere.

[wytbishop]

Found it. Rear O2 harness fell against

the exhaust manifold and melted through the insulationand was grounding.g against the manifold.

As per Ryans suggestion I was unplugging everything and found it that way. Fixed it up and she started first try.

Life is good again. Thanks for your help.

[Ryan]

Glad it worked out! Its always hardest to diagnose things when people have been tinkering a lot, I had totally forgotten about your bay painting escapade.

[wytbishop]

Yeah I had been working on the car all week and when it happened on Sunday morning I was just burnt out. I just needed an evening away from the car. Once I started last night I found it within about 5 minutes and had it running in about 20...lol.

I do have an engine light now though...have to look into that.