1990 mustang 5.0 starter issue

jimdrechsler

Member
Jun 29, 2006
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Can you confirm it is indeed the starter I am having issues with?
Starts fine when cold and runs good. Started having issues last year. The only time it struggles to turn over is when the temperature outside is hot. The past few weeks in coole weather It would turn off and start up with no issues. Yesterday I drove it on a hot and humid day and turned car off. Tried starting it and it wouldn't start. Two little ching ching and then nothing. Then just a click. Waited five minutes and tried again and nothing. Waited a couple more minutes and luckily it turned over. Drove home and turned it off. Tried starting it again and it wouldn't start at all. Went out in the morning and it started right up no problem. I tried the starter solenoid screwdriver trick to see if it would start with no luck. I assume it is starter issue having problems when heated. Thoughts? Plan to buy this.
https://www.rockauto.com/en/moreinfo.php?pk=273819&cc=1133985&jsn=483

I have long tube headers and have been reading threads about getting to bolts and i see it is a PITA. :)
I ALSO HAVE A SUPERCHARGER.

Thanks
 
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Can you confirm it is indeed the starter I am having issues with?
Starts fine when cold and runs good. Started having issues last year. The only time it struggles to turn over is when the temperature outside is hot. The past few weeks in coole weather It would turn off and start up with no issues. Yesterday I drove it on a hot and humid day and turned car off. Tried starting it and it wouldn't start. Two little ching ching and then nothing. Then just a click. Waited five minutes and tried again and nothing. Waited a couple more minutes and luckily it turned over. Drove home and turned it off. Tried starting it again and it wouldn't start at all. Went out in the morning and it started right up no problem. I tried the starter solenoid screwdriver trick to see if it would start with no luck. I assume it is starter issue having problems when heated. Thoughts? Plan to buy this.
https://www.rockauto.com/en/moreinfo.php?pk=273819&cc=1133985&jsn=483

I have long tube headers and have been reading threads about getting to bolts and i see it is a PITA. :)
I ALSO HAVE A SUPERCHARGER.

Thanks
Sound like the starter to me. But check ALL your wire connections before you spend the money. I've seen the wire at the starter get loose, as well as ground wires and cost you a lot of money and time. Long tube headers do put extra heat on starters but, it's worth it. May want to put some heat wrap on the new one, ifthats your problem. Have a blessed day !
 
Thanks for reply. ORdered the bosch one and will replace that. Cheap enough to try and see if it works. I will also check all connections. Now the fun part of reaching those bolts!
 
No Crank checklist for 5.0 Mustangs

Revised 24 May 2018 to add check for backup lights harness.

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 slow crank, 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 .25 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. .

attachments\64167


Voltage drops should not exceed the following:
200 mV Wire or cable
300 mV Switch or solenoid
100 mV Ground
0.0V Connections
A voltage drop lower that spec is always acceptable.

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

attachments\21328


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

attachments\52294



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

attachments\53216


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.

See the Typical start circuit diagram above for wiring information for troubleshooting.

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.

The next check is courtesy of Killing Hours.
For manual shift transmissions only: check to see that the backup light switch harness is intact and in good condition. There is a wire in the harness that loops 2 pins coming from the body side of the harness. This is the bypass for the auto transmission Neutral Safety Switch. If the connector is damaged, oil soaked or missing you will have a no crank condition.

Backup lights harness for 5 Speed transmission showing the bypass loop for the Auto Trans NSS
Courtesy of Killing Hours
attachments\605834