Hello fellow Ford truck enthusiasts,

I have a 62 F100 with the old 292 engine. I have replaced the battery, starter, starter solenoid, battery cables, cable to the starter as well as the ignition coil, points and condenser, rebuilt the carb, replaced the fuel pump, replaced the water pump, and have a new fan belt that drives the generator. When I let the engine sit for a while it fires right up, but when I run it for a little bit, sometimes a minute or two, I shut it off, and try to start it up again, it will barely crank. When it is running, the generator idiot light glows red. Is this indicative of a generator or voltage regulator problem? Also when it does start and run it runs very smoothly.

Dale

 

If you have access to a voltmeter, attach it to the (charged) battery and watch it while you crank the motor. It should not drop below 9.6 volts. If it does, either the starter is faulty and is drawing too much power (quite possible), or the motor is too tight and the starter can't spin it (very unlikely, but remotely possible).
Eric

 

Sounds like the battery isn't charging. Check the generator output while the engine is running. Should be putting out over 14v while running. Was this an issue before you changed everything or a new problem?

 

You might want to look at the timing. If it is advanced too far it can cause what you are describing.

 

GEN light illuminated means no charging - at anything above idle anyway. It may glow dimly at low RPM but should go out once underway. Turn on headlights and heater blower to load up generator, and spool up RPM to around 2000 to 2500 RPM and measure voltage at battery posts. Should see 13.8 to 14.2 or better depending on temperature.

There are some tests you can run to isolate or eliminate the generator versus voltage regulator. Make sure GEN light is not illuminated when key is turned to OFF. This means battery is backfeeding into generator. Disconnect battery immediately if this is the case. Usually the problem is generator brushes are worn out or sticking in the holders. Most common problem.

Generators are heavy, but I'd recommend pulling it and "going through" it, they are very simple and easy to troubleshoot once you understand them. Put your battery on a charger, even though it's new it will be half dead by now. Disconnect all wires at the generator itself. Wire a jumper from ARM to FLD terminals. Either start the engine or spool up the generator with a drill, etc. Should see voltage in excess of 12 volts with voltmeter connected to ARM and GND on the generator. Only run this test long enough to verify output. Still need to inspect brushes in my opinion, I've seen generators pass this test with burnt and stuck brushes.

 

While timing would definitely affect how easily an engine starts (or doesn't) how would the timing cause an engine to barely crank or cause the gen light to come on? He also said that when it does run, it runs well. Timing would be my last suspect.

 

As mentioned above, I also believe there are two things going on here. When using a generator, and the idle is low, your gen light will sometimes glow. As the idle comes up, the light will start to go out. That is if there is nothing wrong with your charging system. If the light stays on all the time,
Also mentioned by crop duster, your timing may need to be backed off a little. You say it starts easy when its cold but when its warm and you shut it down and try to start it again - it doesn't want to start. If it also doesn't even want to turn over very easy - TRY backing off the timing just a tiny bit, maybe 5deg. Lock it down and try starting it again.

All this said assuming your carb is not bowling over.

 

so the battery is fine, and when you let it sit for a while it cranks fine? I'm having the same problem. Do you have headers that are right next to the starter? I think my problem is that the starter is getting too hot. I was going to post the same problem here.

 

OP's 1962 truck has a generator, alternators introduced in 1965.

 

When an engine is cold you are depending on raw fuel to ignite. Raw fuel is hard to ignite and burns very slowly. The piston will have plenty of time to pass top dead center before the fuel is consumed. With a warm or hot engine the fuel is vaporized in the intake, you have a very volatile mixture that will ignite and burn before the piston reaches TDC. If the timing is advanced too far it can cause the engine to crank slow or even try to run backwards.

 

if his problem is the same as mine, the engine has trouble even moving, not starting. it's like it's bound up or something. which tells me the starter is messed up. if his turns over ok, then he has a different problem, and i'll bow out of the conversation.

 

Fixed It

 

Makes sense, but the OP said that it otherwise runs well. Seems that if the timing was that far off it would neither start right up nor run well. With all the parts he said he changed, I'd still be suspect of the "charging system" (aka generator)

 

Sometimes when starters get hot they have problems, but the complaint is "after a minute or two" of run time. Not enough to get anything overheated that's for sure. Could be a bum starter, wouldn't be the first time a "rebuilt" ain't.