Electrical 1991 Gt

What's your timing set to?

Well, sounds like a timing issue to me. If you can get a gun, make sure your timing is set the 10 degree factory setting.

Definitely the solenoid. You need a heavier duty one. I had the exact same problem until I get the red heave duty one from NAPA. The one from autozone (or was it discout auto parts?) was apparently crap.

No Crank checklist for 5.0 Mustangs

Revised 05-Oct-2010 to update Fluke references.

No crank, slow crank and stuck starter solenoid problems have the same root causes – low battery voltage and poor connections. For that reason, they are grouped together.
Use the same initial group of tests to find the root cause of both no crank and stuck solenoid problems.

Since some of the tests will bypass the safety interlocks, make sure that the car is in neutral and the parking brake is set. Becoming a pancake isn’t part of the repair process…

1.) Will the car start if it is jumped? Then clean battery terminals and check battery for low charge and dead cells. A good battery will measure 12-13 volts at full charge with the ignition switch in the Run position but without the engine running.
A voltmeter placed across the battery terminals should show a minimum of 9.5-10 volts when the ignition switch is turned to the Start position and the starter engages or tries to engage. Less than this will result in a clicking solenoid, or slow cranking (if it cranks at all) or a starter solenoid that sticks and welds the contacts together.

Most auto parts stores will check your battery for free. It does not have to be installed in the car to have it checked; you can carry it with you to the auto parts store.

The battery posts and inside of the battery post terminals should be scraped clean with a knife or battery post cleaner tool. This little trick will fix a surprising number of no start problems.

The clamp on with 2 bolts battery terminal ends are a known problem causer. Any place you see green on a copper wire is corrosion. Corrosion gets in the clamped joint and works its way up the wire under the insulation. Corroded connections do not conduct electricity well. Avoid them like the plague...

If the starter solenoid welds the contacts, then the starter will attempt to run anytime there is power in the battery. The cables and solenoid will get very hot, and may even start smoking. The temporary fix for a welded starter solenoid is to disconnect the battery and smack the back of the solenoid housing a sharp blow with a hammer. This may cause the contacts to unstick and work normally for a while.

A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection while trying to start the car: more than .5 volts across a connection indicates a problem. The voltage drop tests need to be done while cranking the engine. It's the current flowing through a connection or wire that causes the voltage drop.

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. .



2.) Check the battery to engine block ground down near the oil filter, and the ground behind the engine to the firewall. All grounds should be clean and shiny. Use some sandpaper to clean them up.

3.) Jump the big terminals on the starter solenoid next to the battery with a screwdriver - watch out for the sparks! If the engine cranks, the starter and power wiring is good. The starter relay is also known as a starter solenoid.

The rest of the tech note only concerns no crank problems. If your problem was a stuck solenoid, go back to step 1.

4.) Then pull the small push on connector (small red/blue wire) off the starter solenoid (Looks like it is stuck on a screw). Then jump between the screw and the terminal that is connected to the battery. If it cranks, the relay is good and your problem is in the rest of the circuit.

5.) Remember to check the ignition switch, neutral safety switch on auto trans and the clutch safety switch on manual trans cars. If they are good, then you have wiring problems.

Typical start circuit...
Diagram courtesy of Tmoss & Stang&2birds



6.) Pull the starter and take it to AutoZone or Pep Boys and have them test it. Starter fails test, then replace it. If you got this far, the starter is probably bad.


Starter solenoid wiring for 86-91 Mustang



Starter solenoid wiring 92-93 Mustang or earlier Mustang with upgraded high torque mini starter.


Electrical checks for the switches and starter solenoid

Remove the small red/blue wire from the starter solenoid. Use a screwdriver to bridge the connection from the battery positive connection on the starter solenoid to the small screw where the red/blue wire was connected. The starter should crank the engine. If it does not, the starter solenoid is defective or the battery lacks sufficient charge to crank the engine.

If the starter does crank the engine, the problem is in the clutch safety circuit (5 speed) or Neutral Sense Switch (auto trans) or ignition switch.


Typical start circuit...
Diagram courtesy of Tmoss & Stang&2birds


You will need a voltmeter or test lamp for the rest of the checks. Connect one lead of the voltmeter or test lamp to ground. The other lead will connect to the item under test.
Look for 12 volts on the white/pink wire when the ignition switch is turned to the Start position. Check the ignition switch first.
No 12 volts, replace the ignition switch.

The next step will require you to push the clutch pedal to the floor (5 speed) or put the transmission in neutral (auto trans) while the ignition switch is turned to the Start position.
Good 12 volts, check the clutch safety switch (5 speed) or Neutral Sense Switch (auto trans) for good 12 volts on both sides of the switches. No 12 volts on both sides of the switch and the switches are defective or out of adjustment. Check the wiring for bad connections while you are at it.

yeah... your starter solenoid welded itself closed. Need a new one.

Someone else who didn't bother to read the posted no crank checklist...

"If the starter solenoid welds the contacts, then the starter will attempt to run anytime there is power in the battery. The cables and solenoid will get very hot, and may even start smoking. The temporary fix for a welded starter solenoid is to disconnect the battery and smack the back of the solenoid housing a sharp blow with a hammer. This may cause the contacts to unstick and work normally for a while."

Ignition switch on column below where the key goes in

blackfive-o, while I guess it's possible that's the problem, it's most likely not. When they go bad, they typically fail to start the car, as opposed to causing it to continually crank. That, coupled with the fact that he temporarily fixes the problem by replacing the starter solenoid makes it a pretty sure bet, that the solenoid is stuck.

OP, sorry man... I'm sure this is frustrating to you. What's frustrating to us is that you just got all the explanation possible in jrichker's post, but you didn't read it, or failed to comprehend it. Please read Jrichker's post, again. Near the beginning, it explains why you're car is "eating" starter solenoids. That is, why they are welding the contacts.

In my case, I told you what happened to me, and how I fixed it. If you bought the starter solenoid from a reputable store or company, they should have come with a warranty, which you can use to get your money back. That's step 1. Step 2: go to NAPA and by part number ST404, or STH404 - I looked it up for you. It also has a 36 month warranty. Conversely, go here and order it online: http://www.napaonline.com/Catalog/Result.aspx?Ne=25000&Ntk=Keyword&Nty=1&Ntt=&N=599001 101991 50026 2026026 29644

I am not guessing about this, and you've wasted too much time and money on poor parts. Buy a quality solenoid, or another crappy one over and over again. If you go with the one I'm recommending, I don't think you'll have the problem again. That will be cheaper than replacing a potentially bad battery, or alternator, although I suppose you'll have to address that problem one day. But if you still have the problem, you'll have to test for low voltage, diagnose it, and go from there.

Good luck. That's the best I can do for you.

Dear Fast Driver, my ignition switch failed on my 92 LX. I just replaced it Sunday. There are 11 wires plugged into it, I have no clue where they all go. But....my turn signals did not work, nothing, but my four ways worked, and my blower for the heater did not work and some switches in my ashtray didn't work. But the car started. So there's a bunch of wires left. Maybe one is causing the problem. I changed my switch and now everything works. My simple suggestion is to remove the shroud around the steering wheel (will take one minute), locate the switch just below the key, see if the plastic is separating from the metal and squeeze it together and try to start the car. This will either rule it out or rule it in. Free test! They are known to go bad. PS: I am no mechanic, but I think it's worth a try! Just trying to help!

Use the Fluke voltage drop test to spot bad connections. It will find them more reliably than anything else.

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. .

It's time to start chasing down your electrical gremlin, then. Good luck, man.