Car is ‘73 2.0 with stock d-jet. Has been running fine, just passed a PPI last Thursday. Late yesterday afternoon I started it to move it. Started fine, ran normally for 15-20 seconds, then quit suddenly. No sputter, just quit as if the ignition was switched off. Since then it will crank over normally, but no fire. Occasionally a very weak cough, but generally not even that.

I immediately checked for spark, and that is good all the way to the plugs. So it is fuel related.

I’ve got fuel pressure, the pump runs it’s brief priming bit when the ignition is switched on, and appears to run while the engine is cranking.

The sudden nature of the failure leads me to think it is electrical, not fuel supply as such. Also doesn’t sound like trigger points, if I understand those right it seems unlikely that both sides would fail simultaneously.

I’m leaning toward a bad wire or connector of some sort, or possibly a D-jet component that has failed electrically.

Any suggestions on likely causes are welcome!

When that happened to me, it was the relay panel in the engine compartment. Switched in a known good one and the car started right up.

Assuming you have confirmed spark, you're probably either getting too much fuel or none at all. You need to determine which, either by smell (gas?), pulling the plugs, or pulling an injector to see if it's squirting.

If no fuel, it very well could be trigger points. If the trigger point connection is unplugged, you'll not get injectors on either side to fire. Check injector connections (one or two may be disconnected) as well as injector grounds. If that all checks out, make sure fuel is actually getting delivered to the rail (could have a kinked fuel line somewhere).

If too much fuel, I'd look to see if your CHT connection is disconnected. I suppose maybe a blown MPS, but I think you can generally start the car with a blown MPS.

Those are my first suspects. I assume nothing else major would have messed with the timing, dwell, or anything else ignition related?

Appears to be no fuel, or perhaps insufficient fuel. Plugs are dry, no fuel smell in the exhaust.

Relay board sounds like it could cause this issue, but I don't have a spare to swap in.

Removed relay board, metered out every terminal. All check out OK. Drat!

Quick two step test to determine fuel or spark:
1. Hook up timing light. Crank engine with timing light triggered. Light blinks? You have spark! No light blinky? No spark.
2. Squirt some starting fluid in intake and then try to start car. Car doesn't evn try to start? Ignition issue! Car tries then dies? Fuel issue!

Both tests done in minutes with no tools.
Shows you which direction to start heading in!!

Yup, did that. Light flashes, so that's why I'm looking at fuel and injection.

Pulled the relay board, metered all terminals, all checks out OK.

Plugs are dry. Pulled the injectors from the left side (1 & 2), cranked engine, no spray or even a drip. Injectors not firing. So apparently no signal going to injectors.

Check the electrical connections in the engine bay. Pay extra attention to the trigger points in the front of the distributor down at the base, the MPS connector, and the connector at the ECU.

I agree that a sudden problem like that is most likely electrical.

--DD

Gang of ground wires under the plenum, all FI grounds in one place.

If you are hearing the pump running, sounds like your relay board and relays are good. Should you need a relay in an emergency, you can pull one from either headlight circuit in the front trunk

Have you checked the injector's plugs to see if there's voltage with the VOM's positive lead on the (+) terminals when cranking? ... (and with the (-) lead to ground). Then check the plugs' other terminals to ground.

That would narrow it down to bad injector ground(s) or the trigger points.


A failed ECU could also be the culprit, but rarely the case ... check the ECU plug & cable too.

One of my stock questions on FI trouble is trigger points.

And the trigger points were the issue. It runs again.

After the last round, I re-checked all the connectors, including the batch of grounds. All looked good. So I pulled the distributor to check the trigger points. They looked OK, the blocks weren't badly worn, nor had they collapsed or anything like that.

But when I checked with the meter, one side had a lot of resistance, the other was pretty much zero ohms. So I cleaned both sets of points and put it back together.

With the cleaned trigger points, it fired right up.

It's always the last thing you check...

Oddly enough, clear back yesterday afternoon as soon as I figured out I had spark I wondered if it might be the trigger points. But I didn’t want to skip any steps on the way, jumping to conclusions often bites you in the @$$.

This time, I shoulda followed my hunch first.

Glad to hear ...

Thanks for sharing the solution!

Q. Why would the tests show spark all the way to the plugs if it was trigger point connection issue? They fire in pairs, so did the bad connection cause it to fire the wrong pairs at the wrong time? I don't get it yet. Sorry if that's a dumb question, but I'd like to understand.

Trigger points are in the distributor, but totally separate from the ignition circuit. They connect to the injection brain only. If they are bad, ignition continues normally but the injection is dead.

Duh, makes perfect sense. So the bad electrical connection at the trigger points was causing the injectors to not fire. Thanks.

Yup. The trigger points are what tells the ECU that the engine is turning and how fast. No signal means the ECU doesn’t think the engine is running, so no signals to fire injectors.