Start, idle, die, repeat

[alternative]

1980 FI 124 will start almost immediately, idle to 1200 RPM, and die. I am baffled by this problem. I know its not timing because before this problem was intermittent, compression is good (140 PSI on all cylinders surprisingly good), the car is getting air because it starts, car is getting fuel for the same reason, and spark is fine for the same reason but I'm not convinced it stays sparking for the entire time... The car doesn't sound like it's being starved for fuel or air because it would struggle before it dies right? This leads me to think its an electrical issue but I have absolutely no idea what I'm doing, anyone else have this problem and/or know how to solve it?

Edit: Could it be the ignition switch quickly cutting contact internally and reconnecting when the engine dies? The battery light is off while running so I have no way to confirm this other than by turning on the headlights and seeing if they flicker with the engine... I'll test it tonight

[davidbruce]

It sounds like you are running on the cold start injector. If you haven't already, join mirafiori.com , go to the lbrary under item specific lookups and download the fuel injection troubleshooting manual. It could save you a lot of time and money. If it turns out to be the relay you can get them from Rockauto. You have to search the Bosch part number as they aren't listed under the car info but that's where I got my spare cheaper. There was the original number and a supercession. I believe they stock the new number. Yes we need to support our vendors but between exchange, shipping and FedEx charges the cost goes up substantially. Not complaining, just stating a fact.

[alternative]

So if I am running on the cold start injector, would that mean the regular injectors are not firing, or maybe clogged up? I tried testing one of the injectors and I got a steady pulse while cranking on cylinder 1. I didn't bother testing the others because I figured if the engine ran for a second, and quite decently for that second then all or most were working fine. Running on the cold start injector does make a lot of sense actually, because when I was working on a hotter day it was hit or miss if it would start for a second or not. Yesterday was a bit cooler and the engine started for that second every time I tried, but didn't start again if I kept cranking.

[alternative]

I've narrowed the problem down to the injectors. Since the cold start is getting fuel it isn't a fuel issue. There were no problems before the issue started with power or acceleration so I can rule out dirty injectors. The injectors haven't failed because the odds of all of them going out at once are astronomical. So far its looking either like a bad ground or no signal from the ECU.

[spider2081]

I believe the fuel pump is powered directly from the ignition switch "start" contacts and is then powered by the air flow meter powering the dual relay to power the fuel pump when the ignition switch is returned to the "run" position.
Do you know if the fuel pump is running when the ignition switch is in the "run" position and the flap in the air flow meter is open?
If you are not sure you might want to measure voltage at the fuel pump when the ignition switch is in the "run" position and the air flow meter flap is open. The pump green/black wire is voltage and the white/black wire is ground.

[alternative]

I've confirmed everything about the car is working except for something with the injectors. I have 12v on both pins of injector 1, and when I start the car I don't get a ground on either pin while cranking, they both stay 12v. I'm starting to get worried about a faulty ECU...

[alternative]

I'm sure everyone here has experienced this at least once, so I'm gonna go outright and say this car is now working perfectly fine. I couldn't believe my eyes when it just started up and ran. I tried unplugging the injectors thinking one was faulty and causing the whole circuit to not work, so I plugged them back in one by one, the engine slowly getting stronger and stronger when I started them with more and more injectors until I got to 4. I plugged the fourth one in, heard a click (probably a screwed up thermo switch), and all of a sudden the engine works perfectly fine as if nothing happened. Thanks for everyone's help tracing this issue, this site is awesome for support.

[spider2081]

I have 12v on both pins of injector 1, and when I start the car I don't get a ground on either pin while cranking,

This is correct. The ground from the ECU is a few thousandths of a second. This is too short a time for a volt meter to respond. Special devices called a node light are used to observe the pulsing signal for the injector. If you have an oscilloscope you might see the pulse pattern with that.