Starter hanging
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Cross-Country
Joined: Mar 2022
Posts: 58
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Starter hanging
Odd problem with my 1977 F750. When turning the key to on, not start, the starter engages and the engine starts, but the starter keeps grinding. If I remove the positive terminal from the battery, the starter disengages and the truck runs fine. I have replaced the starter relay on the fender, but have not messed with the starter. Any ideas? Thnx.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
What type of starter? Is it a traditional starter from this era, or a more modern PMGR starter with the integrated/piggyback solenoid?
What, if anything, was done to the wiring before this started? Did you buy the truck this way, or did it happen at some point after some work was done?
A first look-see would be to verify that the starter relay/solenoid wires are attached properly. Look at the two smaller wires sticking out the front and verify that the Red w/blue wire is on the "S" (usually the left side) terminal/post and that the Brown wire is on the "I" post.
If that checks out, disconnect the Brown wire and see if the symptoms persist. If not, then you probably have a second bad relay/solenoid. Not uncommon these days.
Do you have a volt-meter? If so, remove the Red w/blue wire from the S post and turn the key to ON and check for voltage at the end of the wire. You should see none.
Paul
What, if anything, was done to the wiring before this started? Did you buy the truck this way, or did it happen at some point after some work was done?
A first look-see would be to verify that the starter relay/solenoid wires are attached properly. Look at the two smaller wires sticking out the front and verify that the Red w/blue wire is on the "S" (usually the left side) terminal/post and that the Brown wire is on the "I" post.
If that checks out, disconnect the Brown wire and see if the symptoms persist. If not, then you probably have a second bad relay/solenoid. Not uncommon these days.
Do you have a volt-meter? If so, remove the Red w/blue wire from the S post and turn the key to ON and check for voltage at the end of the wire. You should see none.
Paul
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Cross-Country
Joined: Mar 2022
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Original starter I believe, do not see the integrated solenoid. My small ignition wires look to be both brown. PO was a horrible mechanic and butchered everything, but when I got the truck running, this was not a problem. It has recently developed. It almost seems as if the key is jumped to the start position, but it doesn't feel bad when turning it. Do the old starters have a built in solenoid? Thnx.
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Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
The other side of that question would be how is the relay/solenoid wired? Old style, with the large battery cable on one side and the large starter cable on the other? Or modern style with both big cables on one side and a smaller wire to the starter on the other? Or different still, old style but with the smaller wire to the starter attached to the same side of the relay as the starter cable?
Removing the positive cable removes the capacity to spin the starter, but the alternator can still power the ignition to keep the truck running.
Probably not a great idea to keep doing that though, as you can (I believe) damage the alternator. I've never hurt one this way, but it's been said many times by people who know more than me about such things, that you don't want to test an alternator by removing a battery cable. So I no longer do...
But we need to see how the starter is wired in.
Paul
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Tuned
Joined: Jun 2018
Posts: 458
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From: Arkansas
Original starter I believe, do not see the integrated solenoid. My small ignition wires look to be both brown. PO was a horrible mechanic and butchered everything, but when I got the truck running, this was not a problem. It has recently developed. It almost seems as if the key is jumped to the start position, but it doesn't feel bad when turning it. Do the old starters have a built in solenoid? Thnx.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
Hi Sorry I did not see this before posting my last.
Ok good. Should simplify the search.
Lovely. But we can get past that too. Pull the left side/S wire (or heck, pull both of them!) and test them for voltage, or reconnect them one at a time to see what happens.
You won't always be able to tell by feel. Need to do some more simple testing.
If you have power on the left wire, then the ignition switch is bad, or there is a short somewhere and the wires are crossing.
Nope. Well, some did, like on some older 460's, but on our engines from 302 all the way to 400's they were the "regular" type where they do not use a solenoid to kick the gear into engagement when the motor starts spinning.
Ok good. Should simplify the search.
Lovely. But we can get past that too. Pull the left side/S wire (or heck, pull both of them!) and test them for voltage, or reconnect them one at a time to see what happens.
If you have power on the left wire, then the ignition switch is bad, or there is a short somewhere and the wires are crossing.
Nope. Well, some did, like on some older 460's, but on our engines from 302 all the way to 400's they were the "regular" type where they do not use a solenoid to kick the gear into engagement when the motor starts spinning.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
Sorry again. Just noticed you have an F750? If so, what engine are we talking about?
Not that it changes some of the testing or diagnoses, but we should at least get it out there in case there is something unique about them.
Sounds good. Consistent with your description of the starter.
Hopefully you have a volt-meter for testing. Or at least a test light?
Either one, but especially a meter, can be extremely handy when you own and old vehicle like these!
Paul
Not that it changes some of the testing or diagnoses, but we should at least get it out there in case there is something unique about them.
Hopefully you have a volt-meter for testing. Or at least a test light?
Either one, but especially a meter, can be extremely handy when you own and old vehicle like these!
Paul
Last edited by 1TonBasecamp; Mar 21, 2023 at 12:15 PM. Reason: wording
Laughing Gas
Joined: Aug 2020
Posts: 821
Likes: 292
From: Pelham Alabama
Nighthawking
Did you find out what the problem was with the starter?
If so, Would be nice to reply with what the problem was and how it was resolved.
Reason is, as sometimes looking on Google for a problem it refers you back to this FTE site. and after reading 10 replies and ideas for solutions there is NO answer.
Too many times on here there is a problem identified and EXCELLENT ideas from very smart members and the problem ends up unresolved for further readers..
Alex
Did you find out what the problem was with the starter?
If so, Would be nice to reply with what the problem was and how it was resolved.
Reason is, as sometimes looking on Google for a problem it refers you back to this FTE site. and after reading 10 replies and ideas for solutions there is NO answer.
Too many times on here there is a problem identified and EXCELLENT ideas from very smart members and the problem ends up unresolved for further readers..
Alex
