Weird Electrical Problem

[AaronW]

I've listed this as an electrical problem, since that seems likely.

So my 89 V3500 just had a complete rebuild. A machinist I know completely went through the engine, we deleted the tbi, went back to a 4bbl card, hei distrobutor, new cam, pretty much the works. I've put probably less than 1000 miles on it since the rebuild. I've starting having this problem where when it gets warm, it dies, and if you let it sit for maybe 20 minutes it will start again. When it dies, I've got my dome light, but no dash lights, and it's completely dead, won't turn over, nothing. It's got a brand new start in it. What's frustrating, is that I let it run in my driveway for like an hour the other day, and couldn't get it to die; had it done so, I was going to check continuity from the starter up to where the wire goes into that plug on the engine side of the firewall. There's a little junction point mounted to the bulkhead, that had fusible link coming out of it. I looked that over, and everything seems ok there.

When we did the rebuild, we didn't replace anything in the column. Is there any way this could be the ignition switch down at the botton of the column, or the module where the key goes in? I'm in over my head here, and I'm gonna run out of $$ pretty quick, if I've got to tell a mechanic "go figure it out."

Ideas?

Aaron

 

[Doppleganger]

On cars I have worked on in the past, the ignition switch was known as the cerebral cortex of the electrical system - when it got moody, weird things began to happen (and some things - not happen). I would check that out - they weren't made to last forever.

 

[Ricko1966]

Pull all the wires off the big post on the starter, make sure they are all clean, the ends are crimped good and no blisters on the insulation. Those wires 2 or 3 are going to be fusible links that power the fuse box. If you arent getting good connections or have a wire burnt or broke in the jacket,you are going to have problems. You had all those off when you did your engine swap,so that's where I'd start. Make sure your battery cables are clean and tight you had those off also.

 

[AaronW]

Pull all the wires off the big post on the starter, make sure they are all clean, the ends are crimped good and no blisters on the insulation. Those wires 2 or 3 are going to be fusible links that power the fuse box. If you arent getting good connections or have a wire burnt or broke in the jacket,you are going to have problems. You had all those off when you did your engine swap,so that's where I'd start. Make sure your battery cables are clean and tight you had those off also.

Will do, Rick. I think I'm gonna go ahead and replace the ignition switch, as long as I'm messing with it. doesn't look like that big of a deal to do, I'm sure it's the original, and so I guess will eliminate and additional option.

 

[Ricko1966]

Will do, Rick. I think I'm gonna go ahead and replace the ignition switch, as long as I'm messing with it. doesn't look like that big of a deal to do, I'm sure it's the original, and so I guess will eliminate and additional option.

Don't replace anything without testing it,it just makes diagnoses harder in the long run. Check for power to the ignition switch now,and when the problem happens. Turn the key to the run position,see which terminals have 12v out now and check again when the problem happens. Check for 12v out and wiggle the harness,wiggle the key watch for your test light to blink. I don't suspect your ignition switch. It's possible,but I'd start looking in the areas last worked on first.Everything in the car pics up power from the pisitive lead at the starter,including the ignition switch. Example my car ran fine, but I change to an electric fuel pump because my friend said they are better. Now my car won't start. A smart person would double check everything on the pump installation first,not start testing the ignition coil or plug wires. If you do decide just to throw an ignition switch at it for fun. Test it before installing it.If you install a bad new one you are going to make your job a lot harder,not easier. Because your going to keep for the problem,but now you have two problems.1 keeping you from finding the other

 

[AaronW]

So everything looks good to me, as far as connections go. I figured I'd go ahead and put an ignition switch in it, 32 bucks, so what the heck. Will test first, good point, Rick. I'm pulling the old switch. Had to loosen the column bolts in on the engine side, to get it to drop down far enough, it's pretty tight in there. I've got the old switch unbolted. However, I can't get it to come up off the rod that hooks it to the key cylinder. Anybody know, is there some trick to that? Because you can't see what you're doing in there, I can't tell if there's some obvious thing I should be doing. And weirdly, youtube is failing me, I've only found one video of a guy doing this, and his looked like it just pulled straight up off that rod.

Aaron

 

[Ricko1966]

Did you try wiggling the starter wires to see if you can get the dash lights to flicker? I still think that's the most suspect area.

 

[AaronW]

Did you try wiggling the starter wires to see if you can get the dash lights to flicker? I still think that's the most suspect area.

I've still got to get it to actually die again. It was having the problem pretty consistently, I had a mechanic put a new starter in it, and it died once on him, and them it died on me going home from the mechanics. It hasn't done it since, so I'm kinda flying blind here.

Aaron

 

[Ricko1966]

I've still got to get it to actually die again. It was having the problem pretty consistently, I had a mechanic put a new starter in it, and it died once on him, and them it died on me going home from the mechanics. It hasn't done it since, so I'm kinda flying blind here.

Aaron

Turn the key on,get a friend to watch the dash lights,wiggle the harness going to the starter,hard. Have your friend watch for blinking dash lights. You said they go out ,if you can make them flicker by shaking the harness you have most likely found the problem. Wiggle the ignition switch harness too.

 

[JoeR Jr]

Get your hands on a test light. When it dies, keep the key in the on position, check for power at the HEI, all 3 wires on the alternator and all of the fuses in the fusebox. Once you have the list you'll have a really good idea of where the problem is. Just see what circuits are missing power and grab a wiring diagram. If they are all on the same leg of the ignition switch, or fusable link, or whatever, you'll have it diagnosed.

 

[SS1019]

I would start with double checking all of the grounds. Most "weird" electrical gremlins have turned out to be ground related. It sounds like you had pulled the engine. There is a braided ground wire that goes from the firewall to the back of the right side cylinder head. Make sure that is tight and I might even go so far as to pull it off the firewall connection and clean it. On my 78 it is behind a bunch of undercoating where the evaporator housing attaches. If the head was painted you could put a star washer behind it as well.

I have an old seat belt/key buzzer that I soldered wires to and use them to check for momentary open circuits. It is much easier to listen to the buzzer tone while I'm tugging and pulling on wires than to try to watch a test light. This would help with the ignition switch tests, however the dash lights are not fed thru the ignition switch so that seems an unlikely culprit.

Good luck, it is always difficult to chase gremlins that come and go.

 

[Jimmyperf400]

Same thing happened to me and it ended up being a bad side battery post wasn't completely connected inside behind the post on the positive post. The battery was bought new from napa. Once i changed it to another new battery never did it again

 

[AaronW]

Same thing happened to me and it ended up being a bad side battery post wasn't completely connected inside behind the post on the positive post. The battery was bought new from napa. Once i changed it to another new battery never did it again

Wow, that's an unusual problem... Part of my equation here, is that it only seems to do it when it's hot, so I'm trying to envision problems that might make sense, with that factor in the mix.

Aaron

 

[Snoots]

Pickup coil in the distributor.

 

[Reggie1931]

Very interested in your problem. Please update us when you find the solution.