Stalling & Loss of Power

[aj81spider]

I was just feeling good about my Spider (1981 FI) - yesterday I replaced the hazard switch, fixed a short, and everything was running great. After I finished the replacement I drove it 50 miles yesterday and took it out again today. Drove it another 35 miles today.

At the end of today's run I stopped for gas. Started the car up and while fastening my seat belt it stalled. It never does that, but I didn't think anything of it. Started right up and drove off. About 1/4 mile later it started surging (power dropped out, then came back several times). That stopped fairly quickly, but when I put my blinker on it stalled. It started right up, but for a short while every time I turned the blinker on it would start surging again.

It stalled a couple of more times on the way home - at least one of those times I noticed that the alternator light was on - however it was not on while the engine was running. The battery seems good as I have no problem restarting it when it stalls.

It seems odd (and electrical) that the blinkers would cause problems. I'm not even sure how to go about diagnosing it.

Thanks for any help.

[seabeelt]

Start with a basic voltage test at the battery with the car off and the car running. Should get 12v +/- off and around 14.8v with the car running. This is a basic alternator check.

[GeorgeT]

Check the alternator. Had a similar problem and it turned out to be a bad diode in the alternator. Autozone, Advanced Auto etc. can test the alternator without removing it.

[majicwrench]

IF verhicle cranks and restarts well, alternator likely fine. Will it happen in garage where you can test it?? With engine running, hook volt meter to + side of coil and record voltage. Now turn turn signals on. Voltage should not drop more than maybe tenth of a volt. Check and report back.
Or simple fix just hand signal.
Keith

[aj81spider]

Didn't have a lot of time today (coaching soccer), but I did check a few things in the garage.

- The first time I started it, it started fine. I put the blinker on and it died right away. Unfortunately it didn't die after that so my debugging didn't get too far.

- Battery voltage disconnected = 12.45
- Voltage at battery when running = 13.5
- Voltage at coil when running = 13.44 with some movement.
- Turn blinkers or lights on and voltage at coil dropped to 12.5, with a lot of bouncing around.
- Turn radio on and no effect on voltage at coil

I was looking at the schematics today and wondering how a short in the blinker circuit could pull the voltage down without popping the fuse. Tonight I looked and I found that the (dreaded) PO put a 25 amp fuse in slot A (the blinker slot). I replaced it with the specified 8 amp fuse. It didn't blow, but the problem also didn't occur.

My leading theory right now is an intermittent short in the blinker circuit - that should be fun to find. If you think I'm on the wrong track, or have any other suggestions I'm definitely open.

Thanks for the help so far.

[digitech]

I had a similar issue (the thread should be easily found on this site with a search) and in my case, it was the ignition switch dropping voltage with a significant amount of current drawn through it, i.e. turn signals or brake lights. This in turn dropped the voltage to my coil, causing the subsequent stalling.

[majicwrench]

Digitech has it right. It is not a "short" that is causing your problem, but a circuit with too much resistance. The ign switch could certainly be the fault. Find the wire that feeds power to the ign switch, and the wire coming out of the switch that feeds the ign system and the TS. Voltage going in and volt going out should be the same. If volt is dropping thru switch, that is your problem.
Keith

[aj81spider]

Worked on the problem tonight, but am substantially impaired by the fact that it is not happening. After looking at my ignition switch I think Digitech and Keith are probably on to something - it's almost sad what a hack job had been done to it. A couple of wires are soldered to it, one of the soldered wires has a couple of strands broken. It generally needs to be reworked.

I pulled out the upper console to check on the wiring back there as well, and it turns out my whole car is a hack job! I kind of knew this from other areas (rewired fuel pump - jumpered grounds on the tail lights, etc), but it's hard to believe that someone could mess up so many circuits on one car.

On the plus side I cleaned up a lot and now my heater fan works, the courtesy light works, the cigarette lighter has power and the wires are actually routed cleanly.

I'm sure that my problem is going to happen again (when I'm 30 miles from home). Given the state of the ingition switch I think a power relay is probably in the near future.

Thanks for the help so far - when it happens again I'll pursue the paths you've pointed out. With any luck a power relay and a rewired ignition switch will be a pre-emptive cure.