For year, when I put the A/C on the volt gauge goes down to about 12. Turn the A/C off and it's back up to about 13.5. After running the A/C for a while, if you turn the truck off, and go to restart it right away, it won't fire, acts like a dead battery. But if you run all day with the A/C off, it'll fire back up no problem.

So, I've changed out altenators and battery before, nothing changes. Is there some external regulator or switch to kick up things when the A/C comes on? The idle doesn't kick up either like I think it should.

Craig

 

you could have a external regulator, you could also have (ground issue) as far as idle not kicking up when ac is on, that all depends on what modle you have, for future reference it would help everyone help you if you give the specific model of the truck,ect. dose it do the same thing if you run all the lights? or anything else that puts extra load on the electrical system? Thnx DW

 

I have a similar problem and I haven't added any extra electrical accesories. My Bronco is an '88, so EFI..., but how do you tell if it's externally regulated.

 

_mltdwn12_ For starters, What year is it.
Look on the alternator if there is like four wires running off of the back side of the alternator, and three wires (wire harness) go up to this little box that should be mounted to your fender, you have external reg. and that alternator is a 1G.
A 2G is internal regulated and it has two plugs going into it and are known for burning due to design flaws.
I,m not sure what year 3Gs started, but it has one small lug with an output stud. Hope this helps.

 

Sorry guys, brain dump it's an 89 with a 302.

 

I am having a simalar problem. I have a 90 351 winsor motored unit that I am just about ready to set fire to. As with your truck mine will start just fine when the engine is cold but the longer I drive it the the worse the starting problem becomes. It acts as if the battery has run down and no longer carries the amps to pull the starter. Let it and it starts right up. I tested the battery and its OK. I put another battery in the truck immediately after shutting the engine down to no avail. I have set the timing, replaced the timing gears and chain, new head gaskets, on cylinder was low on compression. new cables, solinoid, starter, tested the alternator. I have done every thing short of a short block.

I went to the Ford house and a mechanic there said he had a situation with a transmission that locked up the clutches in the torque converter when the engine was hot and caused it to stall when it came to a stop. Mine has done that a couple of times , but a trusted transmission mechanic said he did'nt think it was the transmission because my truck didn't have the kind of trans that would cause that problem.

I do notice, as stated in another posting that the A/C affects the altenator output and the engine definatly runs cooler with the A/C off, but this is to be expected.

I cannot help but think the problem is electrical and that somehow the battery is being drained more and more the longer I drive but the battery is showing 14 volts through a volt meter when the engine is on.

I am perplexed and frustrated and ready to bone yard this thing if it's not resolved soon.

 

have you tried checking you base ignition timming?
if your base timming is advanced to much, then when the motors hot can make it act like the starter is draging. Just another thought to put in the pot! DW

 

Ok guys ..the same thing happened to me ..this is what it was on mine ..i had all the same problems ..i replace every thing.. then i felt the starter ..hot as hell ...and to no avail the headers were making my starter hot as hell ..it is only inches away from it ..i made a heat sheild welded it in and now i dont have the problem any more ...good luck ,,it fixed my problem,,,

 

I have spent days timing the engine in every conceivable position
the distributor can be in advanced and retarded.

I don’t have headers on the truck so I don’t think that’s a problem. However this does explain the starter dragging if heat is causing it to short.

One aspect that is also interesting that might be related is that the radio has a lot of static on AM stations but the static goes away when I turn a light on, either the dome light or head lights. Perhaps there is a short occurring causing the starter circuit to ground through a location that can’t carry the starters amp load.
But if so why only when the engine is hot?

 

you may also have a bad power cable, going to the starter, like a bad crimp on one end or the other, or the cable it self starting to break down, Thnx DW

 

I have replaced the positive and negative cables off the battery and even went up a gauge on the positive cable. I also replaced the starter cable from the solenoid to the starter. I also removed the bolt that the battery grounds to at the engine block and cleaned it on a wire wheel to make sure that ground was good.

I think the thing is haunted.