M20 Cuts Out / Won't Start Randomly

[jmairs]

The other night I was leaving work - got out, and my '86 es wouldn't start. And by "wouldn't start," I mean it'd start, then immediately die. Giving it gas had no effect. Towed it home, replaced the fuel filter, and it started. Then cut out again after idling for about ten minutes. Found and fixed a minor vacuum leak, and then it started to run more reliably.

Since then, it is been either starting then dying or cutting out randomly while driving. There seems to be no pattern or warning sign; it just happens. Giving it some gas while starting solves the issue, and it hasn't refused to run since. Meanwhile, when it doesn't decide to die, it has been running MUCH better. However, I'm not sure that I can trust it on the 2.5hr drive I need to take Friday. I'm starting to think it's an electrical gremlin somewhere - my passenger low-beam no longer works (spliced a new line from driver's side to fix), and my passenger front parking light works intermittently (although the signal always works). Plus, it's acting just like our Volvo 740 wagon, which is riddled with electrical problems. I'm going to test / replace the main + fuel relays. What else should I check?

[jmairs]

So yesterday, the car failed to start completely. It turns over, but it just doesn't start. It hasn't been running since. We pulled the outer fuel pump today, and it seems to work. I can also hear it hum softly when someone else is cranking the car. The pump and filter both had gas, and the line coming from the tank had gas. I really can't imagine what else to check to fix this. Does anyone have any ideas?

[billybobjoseph]

Check the throttle position sensor while you are at it.

[shay91]

not sure if it's the same but the symptoms are..

on honda accords this problem is caused by main fuel relay. it'd get hot or stop working all together causing it to sometimes work or other times not at all. They'll throw you all around on figuring it out but that'd be the problem. So that's my guess. Try out the main fuel relay..

[StereoInstaller1]

This sounds like another main relay issue

[jmairs]

Replaced the main fuel relay w/ a new Bosch relay. Still no luck. Engine turns over, but either doesn't start or starts and dies.

[rodpaine]

Replaced the main fuel relay w/ a new Bosch relay. Still no luck. Engine turns over, but either doesn't start or starts and dies.

Check the plug and connection on the Air Flow Sensor. Intermittent starting but not running is something that happens if the plug has dirty connections or a broken wire, or the connector has dirty contacts.
-Rod

[jmairs]

Checked the air flow sensor cables, still nothing. The first time I try starting it, it starts and fails to idle - immediate death. After that, it turns over but doesn't start at all. Last time it started, I saw smoke coming from somewhere on the driver's side - unsure where exactly.

Any other ideas before I tow it to an overpriced mechanic?

[bmwcalvin]

If you see little puffs of smoke it sounds like you have a short or wires that are frying. Check those and your main fuse box to see if there are any that are jumped with no fuse or if they have the wrong fuse. Not sure if you have a cps on that motor, but that is what created a similar problem for me on my m20. You can test it with a volt meter. Just search CPS on here and it should come up. I just pulled about 2 lbs of extra wire out of my car yesterday. PO must of had a integrated cell phone and alarm system at some time..

[jmairs]

I'll take a look and see if there's anything like that I can remove / test.

Just for shits, I tried swapping the OEM Motronic chip with a performance chip I picked up a few years ago. No change, although I did note that one of the pins on the OEM chip was bent and not properly seated...

[Conki]

I have the same issue, just posted about it in another topic:

http://www.r3vlimited.com/board/showthread.php?t=200335

I hope we'll be able to solve these quickly. I hate electrical problems...

[jmairs]

My issue turned out to be a combo of a bad fuel pump relay and loose fuel pump power leads. It has been running well ever since. Hope you find an answer to your problem...

[1fastETA]

I hav had that same problem for the las two months I hav replaced the intank pump, replaced main and fuel relays, new spark plug wires, plugs, fuel filters, new intake boot and hoses and hav not found the problem. I checked the fusible link. I cleaned out the fuel rail and the injectors, swapped icv at least five times. I would recommend tryin to look at all of these things to figure out the problem, I am thinking of replacing the external pump now. Let see how this goes.....:curse:

[Conki]

OK so I replaced the spark plug wires, coil, rotor and cap. When replacing the coil I noticed that one of it's terminals was broken, so sometimes when there was contact I had spark, and when there was no contact the car didn't run obviously. Now with the new coil it starts up right away and idles nicely at around 750 when cold, and it runs reliably.
I got a new problem though; when the engine is warm, the idle goes up to 1100-1400, sometimes with an erratic oscillation.
IDK why it's doing that yet, I might have vacuum leak or a bad tps probably.