1973 F-100 When I drive my truck awhile, then I stop, turn it off. If I go right back to start it, the starter/engine seems to hesitate, then starts. But it only happens when the vehicle is warm. The starter drags. Very hesitant to start. (arr, arr, varoom) My mechanic friend thinks the timing needs to be retarded down slightly. I think maybe I have a grounding issue in the ignition system, or on the starter/solenoid. Anyone experience this? What was the problem?

 

Can't say from here. But all the usual suspects apply in a case like this.
Sounds like the slow cranking is only momentary, correct? If some of the usual items are:

1. Starter getting old.
2. Battery cables getting old (or even a new one failing, which I have had before)
3. Ground cable not in an optimal location, so eventually it just gets harder to start.
4. Ignition timing. Retarding timing a few degrees as an experiment is easy.
5. Starter relay failing somehow. It's still clicking and closing the circuit, but perhaps there is some resistance building up.
6. Headers just getting too close. This heat-related failure of the starter usually takes some time to manifest itself. It might work fine for quite awhile, then just start getting finicky about hot restarts out of the blue.
7. Undersized battery cables finally over their threshold of resistance and the combination of issues was just too much for them.
8. Weakening battery. Whether new or not.

With an old starter I'm not sure how to test it other than either to take it to a local shop for testing, or tossing it out for a new one.

Battery cables are harder to test still. But easy and inexpensive to replace, so that's one of those times when throwing a part at a problem is not out of line.
If they're smaller than 4ga however, you might as well just replace them with larger ones because it's a good idea.

Locations for mounting the ground cable to the engine block should be as close to the starter as possible. Never on the intake manifold. Never on the alternator bolt. Both of those locations work fine for a time, then cause trouble later.

Battery is normally easy to test, but not sure what they would to to take into account the heat issue.

Ignition timing is easy enough to test, but do it when hot. Is all the smog stuff still hooked up or are you running the vacuum advance directly from the ported vacuum fitting on the carb?
If hooked up like the factory had it, it's very likely getting full manifold vacuum under certain conditions. Perhaps one of the thermal valves is failing and allowing too much vacuum (advance) at the wrong time?

Not sure, but any of those could easily contribute to your dilemma.
Worse still, any number of them together could do it!

Good luck

Paul

 

First thing you should do (IMO) is a full BAT deep draw test and starter draw test.

 

If it is the timing, then the starter might be fried by now. If you can check the timing with a timing light, see what it is. Also beware that the harmonic balancer might've shifted, leading to erroneous readings. If it's not pinging or detonating, the timing is - probably - okay.

 

1TonBasecamp, KULTULZ, Meangreen92, thanks for all the options, especially you Paul, quite a list. I should've mentioned that the starter was replaced two years ago, and the engine was installed a year and a half ago, a Jasper re-manufactured. Also, there is no smog stuff attached to my vehicle. I plan to back off the timing slightly, and follow all the grounding this weekend. I tested the battery, no problems there. You all have given me a good set of places to start looking. Thanks again; really appreciate the replies...../

 

At the minimum, you want your battery's negative cable going to the engine block, with another ground strap or wire from the engine block to the firewall of the cab.
If your cables are showing any signs of crustiness and age, they could be the problem.

 

Check the battery terminals - are the the 'bolt on' type ? If so, toss 'um because they build up corrosion under the clamp that you can see.
Check the alternator belt and make sure that it is tight.

 

* can't see

 

Or at least disassemble and wire-brush them every so often...

 

If you want to, you can go back and edit your previous post to reflect your correction.
Up to you, but that's usually a better way.

Sorry if you knew that already and just preferred to do it as a separate posting.

Paul

 

Exactly. And it just occurred to me again that this is a good time to use some electrical grease, or even dielectric grease (which is better?) to keep them from corroding the next time.
Probably should have been done from the factory that way. Too bad we didn't add some ourselves when the trucks were still new-ish.

Paul

 

Had the same issues with my turck, 2 new battery cables and a new starter solenoid and no more issues.

 

I don't mean to derail, but how many grounds should there be? Wrenching on Mopars taught me "the more, the merrier"... Chryslers love grounds. Is two enough on a Ford... batt to block/block to body?

I'm obviously not counting individual components, lights, etc, just the big 'uns.

BTW, mine are crusty and needing replacement too... been chasing a similar hot-start issue and this is where it led me. Playing w the timing helped a bit, but didn't fix the issue 100%... it still shows up on occasion.

 

Same concept as you remember. The more the merrier. And as also said, there is such a thing as overkill, but you can never have too many grounds.

In stock form the Ford trucks (at least the later years) had multiple grounds, but 3 that were the obvious ones.
One to the engine block, one to the body, and one between the engine and firewall.
But many also had a ground strap to the hood, and at least one or two from the frame to the body in the form of slip-on braided cable jumpers running around the body mounts, bypassing the cushions and attaching to the body.

I just redid the ones on my '79 and ran an extra heavy strap between the engine block and frame at the engine mount. Also ran a new, longer negative cable to the engine block at a starter bolt rather than the original location. In addition ran a 10ga wire between the battery negative and the starter relay mounting bolt.

I don't actually remember where Ford put the original body ground. Their common practice back then was to use the main battery cable, and mid-way between the battery and the engine, install a metal clamp that was exposed to the inner strands and bolted to the inner fender.
That's how many of the trucks and cars were, but I can't remember that being the case with my original cable for some reason.
Someone will remember where the body ground was. Or if there was one.

Paul