Help : Starters keep frying

[jakester888]

I'm 5 years into my build... spent the last year driving her around in fiberglass form. 2500+ miles in.

I'm on my 3rd starter. This one only lasted 1 week and it's brand new (not reconditioned). I suspect an electrical problem. I'm using a 93 5.0 Mustang donor engine, Ron Francis wiring harness.

Things I've checked:
1) New battery
2) New terminal connections, tight & clean (see photo).
3) Ran the negative ground directly from the battery negative terminal to the frame and then a grounding strap from that same frame position to the starter mounting bolt (this is my ground point) <-- If I don't do this, the crank power to the starter is weak.
4) New starter. All connections tight.

Any ideas?

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[jakester888]

Update : I believe I have found the source of the problem.

In short : the ignition switch is bad or maybe the firewall mounted solenoid.

Details : I did a simple test on the starter by applying direct current from the battery (by-passing ignition), both the solenoid plunger and starter are working fine - on both the new and older starter. So my starters are not going out. Then, I put a voltage meter check between negative ground and the little + terminal on the solenoid (which is activated by the ignition switch)... boom, no signal on turn-over of the ignition switch. Conclusion : Bad ignition switch. Agree? Now I've got to take the body off to get to it. This guy was helpful : https://www.youtube.com/watch?v=Af-SxRROHzA

[jakester888]

Just for grins I did the following:

I did a voltmeter test between ground and the "S" terminal on the firewall solenoid... the "S" terminal is the lead from ignition switch. Cranked the ignition and no needle on the meter. Then, I quick-jumped the "S" terminal to the battery positive terminal and voila : starter cranks over.

It's got to be the ignition switch. Time to take the body off (which means windshield as well... damn).

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[rich grsc]

I can tell you, you have the solenoid wired incorrectly. You'll have to do a search for the wiring diagram, thought I had a copy saved in my files, but I can't find it.

[jakester888]

I'm not using the "I" terminal. That photo was borrowed from the internet.

[CraigS]

What the heck is w/ the 'take the body off to get to the ignition switch' stuff?

[jakester888]

What the heck is w/ the 'take the body off to get to the ignition switch' stuff?

I don't want to be laying on my back and contort myself to get behind the dash. Also, I've installed the under dash aluminum 3rd party kit - so it's not easy to get in there anyway. Lots of other reasons to take the body off:
1) Adjusting the the steering knuckle
2) Fixing the headlight wiring
3) Re-mounting the coil to the firewall
4) Shimming the steering column
5) Replacing a faulty lighted switch
6) Re-organizing the relays controlling the lighted switches
7) Relocating the computer (currently behind the dash)

[rich grsc]

I'm not using the "I" terminal. That photo was borrowed from the internet.

So you're have electrical problems, and you post some random picture from the internet of something thats not on your car??? You think some how thats going to help find YOUR problem??? what the hell

[jakester888]

So you're have electrical problems, and you post some random picture from the internet of something thats not on your car??? You think some how thats going to help find YOUR problem??? what the hell

Mine looks the same, except no wire coming out of I terminal.

[AZPete]

Jake, one goal during this ignition switch fix should be to make your dash accessible. I mounted the forward edge of my under-dash panel to the frame with a hinge (Ace hardware piano hinge) and rivnuts to the bottom lip of the dash. Then, whenever you need to fix or upgrade anything in the dash, it's easy. And, I'll be watching to see the final cause of your starter problem - that's how we learn here.

[jakester888]

Jake, one goal during this ignition switch fix should be to make your dash accessible. I mounted the forward edge of my under-dash panel to the frame with a hinge (Ace hardware piano hinge) and rivnuts to the bottom lip of the dash. Then, whenever you need to fix or upgrade anything in the dash, it's easy. And, I'll be watching to see the final cause of your starter problem - that's how we learn here.

Great suggestion.

[jakester888]

PROBLEM SOLVED

I went ahead and took the body off - to focus on my list of items. I tackled the starter issue first. Root cause of the problem : the blue wire connecting from the Ignition switch to the "S" terminal on the firewall solenoid was broken and not making contact. Stripped the wire, re-soldered and heat shrinked - problem repaired. Tightened all terminals down.

She fired right up.

The blue wire was as per factory from Ron Francis - I must have torqued it down too tight initially which lead to the broken wire inside the heat shrink.
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