Ok, 91 F 150. with 302 auto. All stock. My issue is the starter won't engage/ the fender mounted solenoid will chatter but the starter won't engage. Talked with local mechanic and he said bad ground. Today I removed my ground cable, cleaned up the mating surfaces on the cable and the frame and block mounting bolt. No start- checked the ground to starter and was ok with multimeter. My battery has 12.66 volts. have the same voltage at the + terminal on the solenoid. I had the same problem earlier this year, replaced the solenoid and starter so don't think it is either of those. What else can I check?

 

Did you already try jumping the fender mounted solenoid?

 

I would not be too fast to assume that the almost-new parts are still good. While the starters are not known for too many early failures (usually if bad, they're bad right out of the box), the starter relay/solenoid/thingy on the fenders are absolutely horrendous in their current reputation.
Over on the Bronco forums there must be a 50-60 percent kill rate within the first week after buying the cheap ones that most auto parts stores sell. Not so bad with Motorcraft, or Volvo branded stuff, or any other super expensive one (45-75 bucks range) but anything is suspect these days.

In fact, it's gotten so bad that instead of buying another new one, many of us recommend going to the junkyard to see if you can find an original still on a Ford vehicle of any description as your source for "new" starter relays.

Ok, so dire predictions aside, there are multiple things that can go wrong.
1. Starter motor itself is failing. If it's pulling too much current sometimes the starter relay will click rapidly like you're experiencing.
2. Starter relay is failing.
3. Poor ground as you already checked. But did you check both the body ground (probably a 10ga wire) AND the main engine ground?
4. Deteriorating cables. Positive OR negative can get old and not always show it. The factory stuff is pretty darn good, but it won't last forever and not everyone has the same good luck. Some will literally last for 50 years, while others may need replacing after 10. What do yours look like?
5. Ignition switch not doing it's job.
6. Neutral Safety Switch partially failed.
7. Probably other things I'm not thinking of.
8. Did I mention the starter relay might be bad?

Good luck.

Paul

 

Thanks for all the tips Paul, sorry I haven't been on the forum, had to go to the Boundary Waters with the Scouts on a 5 day canoe trip. I drove the old girl today and it started every time. I had checked the ground to the body, also the ground to the frame and cleaned all surfaces and applied a bit of dielectric grease. I have another old fender solenoid I might try. The cables appear in good condition, I think most of the OE stuff is much better quality than the crap we buy today. I will keep all this in mind for future reference. Thanks for all replys.