About 6 months ago, I got lucky and got a '91 f150 at auction. It's been a pretty good truck overall, and being 20 years old, it of course has a few small problems. It has the 302 in it, 2 wheel drive, just over 90,000 miles.

The problem I've been having is this: About once a month (approximately), it won't start. It will be completely at random. Sometimes it'll turn like it has a low battery, other times nothing at all. Moreover, if I come back later, it usually starts.

I've also noticed that for the first few seconds, the voltmeter reads low; it takes a moment to get up to normal (this is a newer symptom). I've taken it to Autozone, and the alternator checks out (at least, for the test they do. I haven't pulled it and taken it to a shop yet).

Are the two problems related? What do I need to check out? I know it sat for a while before I got it, and the guy at Autozone suggested the springs on the brushes in the alternator may just be stiff. I don't know, I'm kind of new to this stuff.

Recently, I've put a new battery in it, new distributor cap and rotor, new coil, new solenoid, and new plugs.

Thanks in advance!

 

I would start by cleaning all the grounds, and judging the condition of the battery cables, to see if they need replacing.

 

Welcome!

I notice that you have "solenoid" in your list of replaced parts - are you talking about the starter solenoid? If so, then this is a likely cause of your issue.

You may also want to upgrade to what is known as the "3G" (for 3rd-generation) alternator, you can search on this forum and find many threads on it. The 130A unit will mechanically fit and will provide a significant gain in charging at idle over your stock unit which will help the battery and electrical system live longer.

 

Yeah, it was the starter solenoid. One day I went to start it, and the starter didn't disengage. Since I'd had that problem on another car in the past, I was quick to swap that out.

Why would the new one be causing the problem? (Aside for getting one that was new, but had problems anyway, QC can't catch everything.)

Re battery cables: The cables seem to be in pretty good shape, and I replaced the terminals not too long ago. They were cracked and wouldn't tighten down properly. We thought that was the cause of the start-up issue, but it still persists.

I'm not made of money, so the alternator will have to do (unless it turns out to really be the culprit...after all, you gotta fix your daily driver...) for now. When the time comes though, I plan on asking advice about the best one to get.

 

If it were cheap China junk from Autozone, that would be enough to cause problems!!! Also give the cables a good look-see, if there is lots of corrosion clean them up good and try that, if there are bulges under the insulation Change them!!!

If you replaced the terminals with the clamp on ends with the two bolts keep a close eye on them too..

 

Heh...I bought the solenoid from the local O'Reilly's. Since then they've given me the wrong parts twice, and when I was swapping out the distributor, I got a new one with a bent point. The clerk actually tried to bend it back instead of giving me a replacement.

I don't go to O'Reilly's anymore...

 

Well the cheapest way would be to buy a multimeter $40 or less, and a test light $10 and test each component rather than throw parts at it...you say you come back and she starts right up, is that in the heat of the day, or a cool time?

 

The last three times I've had this problem:

1st time, I drove to my parents house in the morning (but it was a very warm morning). Parked it. Ten minutes later, tried to move it, wouldn't start. Got to it in the evening, started right up. Sun was still up, still very warm.

2nd time, drove to my sons friends house, parked. Ten minutes (ish) later, after talking with those folks, tried to start it, nothing. Popped the hood, checked the cables, everything looked good. It started, albeit as if the battery was low.

3rd time, this after a new battery, almost didn't start, acting like the battery was low (this was about a week ago).

The first two events I realize now I tried to start it again just a few minutes after I parked it. The last one, it had been sitting for an hour or two. At no point could we really call it cool out.

Also, now that I've talked it out with you guys, I realize that this did start after swapping out the solenoid. Maybe I need to check the warranty on it...

 

My guess, and only a guess put in a new starter, and maybe new cables too.

 

The alternator won't be the cause since it will only be working while the truck it's actually running. I had trouble with a new starter solenoid (Motorcraft) which at times wouldn't engage, doing some unrelated work i left it hanging in a different position than the fender location and since then it haven't failed once. I concluded it could be the internals re-arranging themselves a little by gravity overnight, you might want to try that. Some of those spares have sit it shelves in the same position for years, and that could cause trouble.

 

Sounds like a bad battery cable either from the battery to the block or from the battery to the starter relay on the fender.
/

 

My truck would do this same thing, for a little while I would crawl under the truck, wiggle the red wires on the starter, and it would start. Replaced the wires and haven't had an issue in 6 years and counting. It was the smaller gauge red wire, been a long time since I've looked it. I think it was spliced at some point when someone may have replaced the starter, but didn't use the proper connectors (wasn't a sealed splice) so it corroded and sometimes made good contact and sometimes it didn't.

 

Make sure the starter cables are tight, and replace the solenoid again...those are cheap and easy to replace. When you replace the solenoid, be sure to apply dielectric grease to the back of it...

Good luck!

 

OK, thanks for posting the very detailed information on the symptoms, that is very helpful. A bad solenoid usually causes a start or no-start condition (nothing in between such as slow cranking), and since you've replaced it and the symptom is still there, I'd rule that out.

I'm thinking that your starter is on the way out. You may have a temperature-related short in the armature windings which causes the starter to draw abnormally high current as well as to turn slower (making it sound like your battery is low). I had this happen on my 1971 429, and even though I work on cars a lot, it fooled me until I got one of those inductive-pickup ammeters (the Cal-Van cheap one that you hold alongside the big wire to the starter) and found out that my starter was drawing 800-900 amps! It progressively got worse until finally it wouldn't turn over at all.

It also could be a temperature-related bad crimp on one of your starter or battery cables. Like the other poster said, you can use a voltmeter to check voltage drop on each section of cable when the starter is being cranked. I've seen this too, and it's a frickin' bear to find! My college roommate's car had this issue, and it was on the crimped end of the ground cable where it bolted to the block (the ground cable was sparking at the crimp, so some dufus wrapped it with electrical tape - that should have been a clue to me but I totally missed it).

You're going to find it soon - if you can, take it by a shop or auto parts store that has a portable multimeter with a clamp-on multimeter that they can check your starter current with. If it's over 500 amps, something is wrong with your starter (I'm too tired right now to look up what the normal range is, something around 200-300 amps IIRC).