Mystery, Engine Dies occasionally and/or won't start Options

[Literati914]

'72 1.7 with D-jet

Last evening: Finished up replacing a selector input seal on the transmission, buttoned it all up and went for a test spin around the neighborhood.. about two miles in to it, I felt a slight hesitation before braking for a medium speed turn, engine dies right after completing the turn. Pull over, and it won't restart. Not hearing the pump now (but it had seemed kind of loud earlier) (new pump w/ about 300 miles on it), so I switch out the relay in the engine bay. Now I can hear the pump, and it starts and kind of idles for like 4 seconds. After that it basically just cranks and starts for a second or two or three. So we pulled it home, 'cause I wasn't far.

Today: I pulled the front pre-pump (re-usable) fuel filter and cleaned it. There was some crud but I had expected more tbh. Then I replaced the rear fuel filter with a new one. Car starts right up and I immediately put 7 miles on it. A few hours later car starts up fine again, put another 8 miles or so on it.

This evening: Starts up fine, drives to hang out with friends. Then it will not start. Wait a couple hours and it starts up and drives home like no problem. Pull up to house, move trash cans while the car is idling - and it dies!

This has been a bit of an on-going issue with very similar senarios over the last several outings. Seems like a fuel issue to me, but wtf.

It would be funny if not so damn frustrating!

Any thoughts? (besides ditching the stupid d-jet crap)

[Superhawk996]

Seems like a fuel issue to me, but wtf.

Any thoughts? (besides ditching the stupid d-jet crap)

Sure sounds electrical to me. Maybe by fuel issue you mean the pump not getting power?

If you truly believe it’s a fuel issue, the first place to check is that your lines under the tank aren’t getting kinked.

[emerygt350]

Does it try to start or just spin over? Have you tried starter fluid when it is in this belligerent state?

[GregAmy]

Jumper the fuel pump relay, short wire between terminals 30 and 87.

This is not a long-term fix for two reasons: the pump will continue to run with the key off and kill your battery, and it's a safety hazard should you get into a wreck (pump will not stop a-pumpin' with the engine dead).

I'm becoming redundant, but I had a similar issue that was fixed by removing the fuel pump relay and *carefully* spreading the quarter-split pins on the relay *slightly* with a razor blade. That relay should fit into the board quite snugly; if it's loose it may be losing conductivity.

[Literati914]

Seems like a fuel issue to me, but wtf.

Any thoughts? (besides ditching the stupid d-jet crap)

Sure sounds electrical to me. Maybe by fuel issue you mean the pump not getting power?

If you truly believe it’s a fuel issue, the first place to check is that your lines under the tank aren’t getting kinked.

TBH, when it randomly stopped on me the other night I was on a very dark back road.. trying to make sure I was completely off of the road, calling my son to come pull me home, racking my brain for things to possibly check while using my phone light - you know how it is, busy! I replaced the FP relay but honestly wasn't necessarily listening for the 1.5 sec. prime at the FP from the one that was already installed. I did think to listen for it when I replaced the relay and it was there and the engine seem to try to start better with the replacement relay (4 sec or so).

The slight hesitation I felt before it dyeing made me think fuel starvation, but yes it could be electrical too.

I looked at the lines under the tank when I cleaned the front fuel filter.. they looked ok to me. I know the suction pressures can cause movement in the lines - but then it'll also run many miles at a time without an issue. And sometimes fail to start without any previous suction built up in the lines.

[emerygt350]

Seems like a fuel issue to me, but wtf.

Any thoughts? (besides ditching the stupid d-jet crap)

Sure sounds electrical to me. Maybe by fuel issue you mean the pump not getting power?

If you truly believe it’s a fuel issue, the first place to check is that your lines under the tank aren’t getting kinked.

TBH, when it randomly stopped on me the other night I was on a very dark back road.. trying to make sure I was completely off of the road, calling my son to come pull me home, racking my brain for things to possibly check while using my phone light - you know how it is, busy! I replaced the FP relay but honestly wasn't necessarily listening for the 1.5 sec. prime at the FP from the one that was already installed. I did think to listen for it when I replaced the relay and it was there and the engine seem to try to start better with the replacement relay (4 sec or so).

The slight hesitation I felt before it dyeing made me think fuel starvation, but yes it could be electrical too.

I looked at the lines under the tank when I cleaned the front fuel filter.. they looked ok to me. I know the suction pressures can cause movement in the lines - but then it'll also run many miles at a time without an issue. And sometimes fail to start without any previous suction built up in the lines.

Did you double check your coil connections while you are poking around.

When I was having vapor lock issues the pump wouldn't even sound like it was running but I doubt this is vapor lock.

[Literati914]

Did you double check your coil connections while you are poking around.

When I was having vapor lock issues the pump wouldn't even sound like it was running but I doubt this is vapor lock.

I looked at the coil connections yes.. none of the 4 were unattached (I have an electronic ignitor points replacement), and I also wiggled them around a bit to no avail. I have actually thought about replacing the female spade ends on those wires with small ring fittings though, as they never feel as tight as I want them to. But they've worked until now, so.. plus the engine started right up the next day (after fuel filter cleaning).

[Literati914]

I'm becoming redundant, but I had a similar issue that was fixed by removing the fuel pump relay and *carefully* spreading the quarter-split pins on the relay *slightly* with a razor blade. That relay should fit into the board quite snugly; if it's loose it may be losing conductivity.

I had thought of jumping the FP while on the side of the road but could not locate the little loop of wire I thought I had stored in the glove box, for just such a situation.

I will certainly spread the relay pins, seems like good advice, thanks.

[ctc911ctc]

I had this very same problem that only presented itself when it was very cold. I had to sell the car before I figured out the problem that was in 1975. '70 1.7

Most likely culprit?

Ignition switch - these will fail exactly the way you are describing. I would jump the ignition wire - or check for voltage at the ignition coil.

[Literati914]

So if an ignition switch starts to fail - you would still get strong cranking, just no light up? I've never turned the ign. switch and just gotten silence.

[ctc911ctc]

Two separate functions - Grinder is a larger wire (Yellow) that activates the starter motor solenoid. There is another wire (red?) that is for the ignition.

When you are cranking both are energized, when you stop cranking only the ignition wire is activated. When the key is turned to the off position, both are no longer energized.

If you have never replaced the ignition switch, it is a very common place for this type of trouble. I have changed 2 in the last 5 years in a '74 2.0.......

Many people put a relay in front of the solenoid to remove the current draw through the ignition switch.

Intermittent problems are maddening, we have all been there - attack systematically and you will get conquer this gremlin ......

So if an ignition switch starts to fail - you would still get strong cranking, just no light up? I've never turned the ign. switch and just gotten silence.

[Literati914]

so just to beat a dead horse regarding the ign. switch, and to confirm... a car that's been out running the streets, then left to idle for a bit, could die from a bad switch? - I ask because I'd never heard that and it doesn't seem completely logical (to me) - but then I know nothing of how that circuit works.

[chmillman]

If turning the key, the engine will always crank but won't start, and if in the on position all of the other electrics work, then I think it would be safe to assume that it is not the ignition switch. (not a bad idea to change it anyway, but that's another story)

As others have said, it sounds like the electrical supply to the fuel pump might be iffy - especially if you don't hear the pump pumping when the problem occurs. I guess a fuel pressure gauge installed temporarily might tell you that at least you have no fuel pressure at that moment.

I would also check all the other important EFI contacts/connections in the engine compartment. Intermittents there can also cause havoc.

[emerygt350]

If turning the key, the engine will always crank but won't start, and if in the on position all of the other electrics work, then I think it would be safe to assume that it is not the ignition switch. (not a bad idea to change it anyway, but that's another story)

As others have said, it sounds like the electrical supply to the fuel pump might be iffy - especially if you don't hear the pump pumping when the problem occurs. I guess a fuel pressure gauge installed temporarily might tell you that at least you have no fuel pressure at that moment.

I would also check all the other important EFI contacts/connections in the engine compartment. Intermittents there can also cause havoc.

And if you can get some starter fluid in there the next time it does this you can learn whether it is electrical or fuel. If it starts on fluid, you know it's probably fuel related. There is the ever so small chance it is a weak spark and starter fluid allowed it to fire, but that is a pretty fringe case. Or pull a wire and see if it is getting spark.

Again, I can never remember, but does that stupid no start relay under the seat on 74s cut out the fuel pump or the starter motor?

[Superhawk996]

Again, I can never remember, but does that stupid no start relay under the seat on 74s cut out the fuel pump or the starter motor?

Starter

[Literati914]

This car does not have the under seat relay set up, '72.

[emerygt350]

This car does not have the under seat relay set up, '72.

Ahh yes, I was confusing you with the other thread with the 74.

[Literati914]

Back to thinking about this mystery issue again: Car starts and runs but sometimes will either not re-start after stopping for gas etc, or will die while driving. D-jet 1.7.

A couple possible issues, I've thought of:

Fuel pump and a pre-pump filter (as well as an in-tank sock) are up front adjacent to the steering crossmember. So you'd think this wouldn't be vapor lock - besides it's died while out driving. But then again it is under the huge plate covering the steering rack - so no real air circulation either. There is also a fuel filter just before the engine shelf in the back. So, could this be too much filtration causing the pump to work too hard and over heat maybe? Thoughts?

Also, there's a twist with fuel routing: I'm using the 8mm line for supply to the engine and the larger 9.5mm line as the return. Knowingly opposite of the correct configuration for early cars.. Later 914s also used 8mm for supply - so I thought that would be fine. And yes it does work just fine (unless having a larger return causes some kind of mysterious intermittent issue of course). I mean, this wouldn't cause the pump to over-heat, right?

If you think the above is significant and wonder why I'd route the fuel this way? - the short answer is because this car already had the 9.5mm/8mm fuel line set up like early cars are supposed to, and already in stainless. I was unaware there was even a change in line sizes on the later cars until I switched the pump to the front. Beside I never heard anyone mention a NECESSITY to replace fuel line sizes if moving the pump to the front on early cars. Surely people have done the same, right? BTW - I could have made this work with the standard early car configuration but finding a standard fuel filter with [9.5mm IN/ 8mm OUT] was/is impossible. BTW, when I say 9.5mm/8mm I'm also talking about 3/8" & 5/16".. I've looked as well as asked here in the past, but if anyone knows of one please divulge.

[Ishley]

I’d check for fuel line kinks under the tank. It can be frustrating to get it right.

[wonkipop]

Back to thinking about this mystery issue again: Car starts and runs but sometimes will either not re-start after stopping for gas etc, or will die while driving. D-jet 1.7.

A couple possible issues, I've thought of:

Fuel pump and a pre-pump filter (as well as an in-tank sock) are up front adjacent to the steering crossmember. So you'd think this wouldn't be vapor lock - besides it's died while out driving. But then again it is under the huge plate covering the steering rack - so no real air circulation either. There is also a fuel filter just before the engine shelf in the back. So, could this be too much filtration causing the pump to work too hard and over heat maybe? Thoughts?

Also, there's a twist with fuel routing: I'm using the 8mm line for supply to the engine and the larger 9.5mm line as the return. Knowingly opposite of the correct configuration for early cars.. Later 914s also used 8mm for supply - so I thought that would be fine. And yes it does work just fine (unless having a larger return causes some kind of mysterious intermittent issue of course). I mean, this wouldn't cause the pump to over-heat, right?

If you think the above is significant and wonder why I'd route the fuel this way? - the short answer is because this car already had the 9.5mm/8mm fuel line set up like early cars are supposed to, and already in stainless. I was unaware there was even a change in line sizes on the later cars until I switched the pump to the front. Beside I never heard anyone mention a NECESSITY to replace fuel line sizes if moving the pump to the front on early cars. Surely people have done the same, right? BTW - I could have made this work with the standard early car configuration but finding a standard fuel filter with [9.5mm IN/ 8mm OUT] was/is impossible. BTW, when I say 9.5mm/8mm I'm also talking about 3/8" & 5/16".. I've looked as well as asked here in the past, but if anyone knows of one please divulge.

it should not be a problem you reversing the lines.
i take it you have now moved the fuel pump to the front of the car.
its a pressurized line now so smaller diam works. in essence you have a stretched out pressurized circuit when it came to the later cars compared to the early cars. its an injector line that is running from the front to the fuel pressure regulator.
the bigger diam line would only necessary to use as supply if the pump was under the engine shelf.

the fuel filter you still have under the engine shelf could be a problem.
is it a high flow pressurized filter you have fitted there?
they are larger diam metal cylinders. it is essential that it is one of those in the configuration you are describing you have. if its high flow it should be fine.

standard type filter location would only be fit for purpose between tank and pump up front. must be before the pump.