Engine shuts off randomly

[spider2081]

have you measured the resistance of the new pick up coils pretty sure it should be about 750 ohms. my meter leads are too big to reach the spade pins in the connector so i use my wife sewing needles.. Just have to be careful I put them back or she gets an attitude.

[jeffshaw57]

Fiat friends helping me find the gremlin - Last night I cranked it up and let it idle with a battery charger connected to the battery. The voltage read at the pink wire and ground was 13.6 while running. At 20 minutes the engine shut off just like it has been doing. I noted the voltage was still at 13.6 (no change). I gave one shot of carb cleaner in the air filter within a minute of the shut off and it started right up. I let it run without the fan until the temp redlined and the coolant boiled and it did not shut off! I shut it down for the night. So, what is it???

[tima01864]

usually points to the temperature sensor but you have a carbed engine.

[zachmac]

Fuel pump or fuel pump relay overheating? Does you fuel pump still run off the factory setup with the starting and running power supplied as a safety precaution? A bad oil pressure signal would also then cause the fuel pump to lose power. As the squirt into the carb started it it is not spark so you've eliminated ignition. This is a fuel starvation issue. Not sure though why it wouldn't repeat after restart?

Try a direct jumper to the fuel pump so it is not being powered through the safety relays and see if it runs past the 20 minutes.

[aj81spider]

I'm not convinced it's fuel related. If it were an overheated pump, for example, when you sprayed carb cleaner it would start, but then would die when the carb cleaner was used up and no fuel was following it.

If it's an intermittent electrical connection (which it feels like to me) then some of your experiments are producing suspect data. For example, spraying carb cleaner and the engine starting may not be related. I'd start keeping a log of everything you are doing and write down the things you absolutely know are true. Then you can start evaluating your debugging against the previously observed known facts (and every once in a while challenge whether the known facts are really known, or could be misleading information).

If it were me I would start looking at things when it wouldn't start. That will be your most valuable information. If it's an intermittent problem (electrical or otherwise) the fact that it starts could only mean the intermittent problem is not there any more, not that anything you did caused the car to start.

Here are some thoughts.

You mentioned in an earlier post that the starter motor is working when it won't start. If that's true then at least some electrical connections are working. However the ignition switch could still be intermittent, as the starter connection is through a different set of contacts. RRoller suggested looking for spark when it won't start. That would be my first step. If you don't have spark then it's a matter of figuring out why (and hoping that the car doesn't start again while you're looking!).

I would want to understand why the car won't start with the new pickup coils. I'd make sure I bought the right ones, but that seems to be a clue to me. I'd double check the new coil as well. If it's the right one then I'd want to know why the car won't go over 2000 RPM with it. Both of these issues might be because you have the wrong parts, but if you have the right parts then I think they are clues.

Feel free to ignore all of this. I'm not that great a mechanic, but I do think a more methodical approach will get you to the answer quicker, and I think that some of the data you've collected so far is not necessarily indicative of where the problem is.