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Generator not charging

3

37chief

Well-known Member
Location
California
The generator on my 63 ford f 100 doesn't charge. The generator has a G terminal, and a F terminal. On the back there is a thick wire connected. Anyone know how to test these things to find out if it is the regulator, or bad gen. Thanks Stan
 
Has that generator ever had brushes installed?
You should have voltage on your F terminal with the engine at 1/2 throttle or better. I have a flashing light connected to my generator since it doesn't have voltage on F terminal unless the engine is running on my garden tractor. Hal
 
You can spend money to fix it, but often a few good smacks will make them work. I learned this from a repair shop fourty years ago, and you can guess every repair shop is not so honest.
 
Put a jumper wire between the BAT and ARM terminals on the voltage regulator. Also attach a wire to the F (field) terminal on the generator. Start the truck, and ground the field wire on generator. If you then get charge, which should vary in amperage with RPM of engine, its a bad regulator (jumber between BAT and ARM takes the regulator out of the circuit). If you still don't get a charge, its the generator.
 
If there are two big post/studs out the case, the one is often labeled A or ARM or GEN or G while the other (sometimes slightly smaller) is labeled FLD or F. Most are labeled ARM and FLD or at least A and F instead of Gen which is seen on many Voltage regulators.

NOTE some Ford products are B Charging systems

The output is across the ARM/GEN A or G and case frame Ground while the current passing through the Field (F or FLD) windings regulates the output.

If you run my Troubleshooting Procedure below it will describe how to Polarize and also has a test to determine if non charging is due to a faulty Generator versus a faulty Voltage Regulator. It also has a Motor Test which can provide insight if the genny is good or not.........

My procedure is for Class A charging systems ONLY and isnt exact for Class B's

John T
Class A Troubleshooting
 
DO NOT ground the field terminal on a 60's Ford Pickup generator. As John T says, they have a B field circuit (internal ground field) where the regulator feeds power to the field terminal instead if grounding it like in an A circuit generator. Shorting the F terminal to ground with the regulator connected with the ignition on will burn up the regulator.

To test a B field circuit Ford generator by full fielding it, connect a wire to the F terminal and connect it to full battery voltage.

During a full field test, turn off all lights and accessories and do not run the truck above fast idle, as the regulator is bypassed and a good generator will charge well above a normal 14V.
 
I had a 1963 Mercury I bought used in 1965 from the dealer. It was my first car that had an alternator and even though it only had 10k miles on it the battery wasn't getting charged. Had to replace the rectifer/regulator. It was originally bought new by one of my project engineer's. He wanted $1800.00 for it and the dealer sold it for $1600.00 and it had that breezeway window in the back. I ran it to FL in 1967 and the interstate posted speed was 70mph and it just cruised nice at that speed. Only saw one minor accident. Hal
 
I seem to remember from the old Motors repair manuals, that the easy and safe way to full field test those old Ford generators is disconnect the F wire at the regulator and touch it to the regulator bat terminal. This full fields the generator without adding any wire and disconnects the regulator field relay.
 
Probably easier to retrofit with a alternator. Plenty of instructions here for tractors - shouldn"t be that difficult on a car.
 
Probably easier to retrofit with a alternator. Plenty of instructions here for tractors - shouldn"t be that difficult on a car.
 
Well, geez. . . It worked with my '51 Chev.

So unless you've got a '51 Chev, disregard what I posted. Might be OK for an early '52, as well. But don't count on it.
 
THat generator could be an autolite if so it could be as John T indicates. Autolite Generators have a sheet metal band covering the brushes.
If it is a FoMoCo gen it will have three terminals F (small) G (small) and an output stud on the end, (no metal band)
If this is the gen, do not use Johns tests
To see if this gen is good, disconnect the F and G terminals, Ground the G terminal, start the engine and run above idle (put a penny between the idle stop screw and the throttle link) Put battery voltage to the F terminal while reading a volt meter attached to ground and the output stud. If 14 volts or more the gen is OK.
this is a "B" circuit generator!! Jim
 
The generator is a FoMoCo as you described. It does motor when 12 volts are applied. I suspect it is the regulator. Didn't have time to do a lot of checking. I will tackle it tomorrow. Thanks for all the replys. Stan
 
If you can expose the workings of the Reg. gives the points a touchup., been half a century one would presume.The old manuals used to have this itemised.
 
Sorry Mike, I did not want to throw mud at your advice, as I know it was well intentioned and would be the correct way to "full field" test an A circuit generator like the 52 Chevy you mentioned.
I felt I had to open my yap because using the full field test for an A type generator, on a B type like the Ford pickup, will destroy the regulator.

The reverse is also true, using the full field test for a B type generator on an A type, will also cook the A type regulator.
 
LOL- that test is about the only one I ever knew how to do! But didn't know about the A/B thing- lucky I always had Delco stuff back in the day. I'm glad you set the matter straight, for the sake of the guy who asked the question.
Wonder why Ford always had to be different? Had different automatic transmission fluid, too. Hmmmm. . .
By the way, I'm not much of an electronic menace any more- I know that pretty much anything a "home mechanic" tries to do to modern equipment will let the smoke out.
 
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