Ok, I've searched and searched but can't find my issue anywhere. I have a '78 Pickup 20r.

A few months back it would crank very slowly from time to time as if the battery didn't have a full charge, even though it did. The rest of the time it would start right up. The slow cranking has been getting worse and worse until now it wont start at all. I get max of 3 slow turns from the starter, even when trying to jump start it.

If it helps to figure out the issue, once I tried to turn on the headlights and it almost killed the engine. When I turned them off the engine ran fine. It only happened once. So wierd. Ground issue?

I replaced the alternator, battery, and starter a few months back when this all started.

The wierdest thing is that when I tried starting it a few days ago I noticed smoke and smelt burned wire. I found that the ground wire from the engine to the firewall was melted as well as the one wire from the alternator -the big wire in the 3 prong connector(sorry, I'm a toyota newb).

Any ideas would help. I'm thinking it's a ground issue but I don't know where to start. Does anyone know what that alternator wire goes to?

 

Ok, so I went ahead a replaced all the ground straps I could find. I also cleaned up a bunch of random wires from the previous owner's aftermarket additions. Who knows what they all went to.

Now the engine cranks with no hesitation at all but still wont start. I tested the voltage on the + end of the coil with the ground on the chassis and it was at 14-15v while cranking.

I then tested the coil + and - while cranking and I get nothing.

So bad coil? I just replaced it so I don't know why it would go out.

 

It sounds like you fixed the slow cranking problem by cleaning up (and replacing the burned one?) grounds. Are you getting spark at the plugs?

Did you replace the big wire from the alternator that burned up?

 

Sorry for the delay. Went out of town. Finally back to this annoying problem.

So I replaced the big wire from the alternator that fried. I also replaced the ignitor and coil with ones I know work. Still nothing.

Replaced the mag pickup in the distributor and gapped it. Nothing.

I tried the gm conversion. Nothing.

I tried an msd conversion. Nothing.

I went back to stock setup.

So new spark plugs, coil, ignitor, pickup, cap, and rotor, and ground straps. Turns over fine but no spark at all.

Please someone help. I'm going through everything but can't figure this out.

 

Looks like that bigger wire in the alternator plug is a ground wire. I traced my wire back and it appears to be on a ground with the ignition coil. Its the black wire under the mounting bolt. See picture:



Also in case you don't know Autozone has free wiring diagrams for our truck online. I looked up your year/model and found this which confirms my thoughts on it being a ground. See picture:



If you look at the alternator wiring on the left side, there is a wire that comes out and goes to ground. I believe thats what your looking for. Cam any other yotatechers' confirm this? Hope it helps.

 

PM an email address and I can send you the pdf on the wiring for your truck. Next question is since you put on a new ignition coil and still have no spark its either wired up wrong or maybe the 15A ignition fuse is blown. Check it yet?

 

Thanks so much for your help. I'll use the diagram tomorrow and track down the wire. I know I don't have any kind of ground wire attached to the coil mount so perhaps I can create one. I'll keep you posted. Also, the fuse was the first thing I checked. I wondered if there was another fuse hidden somewhere I didn't know about.

 

Anymore news on this? Mine is having a similar issue.

 

Have you changed the voltage regulator, mine had a similar issue changed the regulator and that fixed the issue

 

i thought i saw something on the "15A engine fuse" being hooked up to the alternator & it will blow if there is a short somewhere on the otherside of the fuse. it'll pop & prevent spark or just ground out & mess everything up... it's because the hot lead on the otherside of the fuse going to the back-up lights & reverse switch on the tranny will short out against the tranny case & cause you lots of trouble. that's at least what I saw. mine's making trouble w/fuse, blinkers, reverse lights, fuel/temp gauge, charge light, pop's fuse, etc.