Hi,
My 1989 F-250 (110,000 miles) does not start reliably. Sometimes it cranks slowly but won’t fire up, sometimes just one click, sometimes nothing, and sometimes starts beautifully. I have had bad luck with mechanics (they replaced the battery and alternator) and at this point would prefer to do it myself. It has new spark plugs and wires. I am solo, so some tests are difficult. Starter, Solenoid? Switch? Any best guesses? Thanks.
Bad starter
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The first thing I would check is the battery cables. Take each connection off and clean off any corrosion, both on the battery post and the connector/clamp. And do both ends of the cables.
It could also be the ignition switch or the starter.
Some simple checks with a voltmeter would narrow it down.
Thank you. Battery cable ends have been replaced at the battery, but I have wondered about the ground connection. Will clean it up, then check the others.
Try replacing the starter solenoid under the hood/right fender.
https://www.rockauto.com/en/moreinfo.php?pk=1005849&cc=1124288&jsn=487
Tester
One more possibility to add to the list is a failing key cylinder.
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There’s a lot of possibilities for causes of fails to crank or cranks slowly. Best approach imo is to make sure you have a good battery, fully charged, and good battery connections to the battery posts as the first step. If that doesn’t solve it, measure the voltage at the two terminals of the starter motor, terminal to starter case. Both should be 10.5 volts or above during cranking. If they are above 10.5 volts, and you don’t get a satisfactory crank, replace the starter motor.
The way I do that measurement, I make up a pair of long wires with alligator clips on both ends, hook one end at the starter motor terminal and starter motor case, and run the other end into the passenger compartment, where I hook that end to my shop volt meter. Then I just sit in the passenger seat, turn the key to start, and watch the volt meter. This is easier to do if you use an analog volt meter, one that has a needle that swings to the voltage. I do the measurement for the first terminal, then I switch the leads at the starter motor to the second terminal and do it again.
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Thanks all. I have a plan now.
You go, goldilocks!
I take this to mean that you just replaced the terminals…not the entire wire. Some are so corroded under the insulation that it raises the resistance so high that the heavy load of electricity for the starter cannot pass through the wire.
I would replace the entire cable…including the ground.
Yosemite
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Sometimes if you bend a battery cable in the middle, you can feel the brittle corroded wiring inside breaking.
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Yes, that is what they did in a repair shop and charged me $70 for it. Still makes me mad. Might be a good idea to start fresh there. Thanks.
Those battery cables tend to be expensive. I think I paid about $25-$30 for a set a while back. $70 parts and labor to install a new pair of battery cables seems pretty reasonable.
Would be good, but they only replaced the clamp on the negative and on the positive as well. Then I discovered the clamp on the positive was fractured, so took it back to them. Got a new positve cable installed at that time. Long story… sorry.