About 2 weeks ago, Betty came home and said her 74, 1.8L Ljet 914 was intermittently cutting out. I took it out to test drive it, and sure enough, it will randomly cut out. Sometimes mildly, sometimes it feels like the engine shuts off completely, then turns back on.

So I started troubleshooting.

Nope, grounds for the injectors are fine.

Put the LM-1 in the tailpipe and had her drive it. Every time it cuts out, the LM-1 shows it going lean. I put an L-Jet tester I have on it and ran through all the tests and it shows as working fine. I had it running in the garage, and I went through a "wiggle test", wiggling every wire and connection on the engine. Nothing I do can replicate the issue in the garage.

So I started throwing parts at it.

To date I have replaced:

The air flow meter.
The fuel injection wiring harness.
The double relay.
The dropping resistors.
The fuel pump.
The ECU.
The CHT.
The whole distributor with a different pertronix, and tried points too.


Nothing I have done to date helps. So I am hoping the collective knowledge of this place will help. I have checked all the simple stuff already. This is going to be hard to fix, whatever it is.


I am now to the stage, and looking for suggestions.

Ignition switch.

My 911 was doing this, good news is a learned all about the 3.2 system.
It was the ignition switch in the end.

Clay, that sounds like an intermittant bad connection or wiring break....the 914 descendants of the traditional "old VW electrical gremlins"!

When I lived 3 blocks from the beach, about every 6-12 months my 73 2L would do that, & the connections on the relays board, ECU, FI's & pretty much everywhere were getting crudded up with corrosion/oxides. TX is mostly dryer than coastal CA, so it could take your 914s longer to get to that point.

So you might try going thru & cleaning everything off then spray it with connection oil (Wurth or similar) to keep them clean.


Tom
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I just had the exact same issue. Turned out to be the FI wire at the dual relay.

I replaced the whole FI wiring harness already.

Wiggle the key.

I can make mine happen or not.
Mine depended upon how hard I put the key into the ignition.

Hard to make happen, sucks when it happens.

Maybe its fuel related? dirty tank sock? dirty fuel filter? intermittent pump? clogged injectors? Failing resistor pack?

Maybe its ignition related, coil going bad? plug wires broken? Cap/rotor ok?

I had a '78 Honda SOHC 750. As I left Oklahoma it started doing this a bit...then more and more. Finally it quit all together so I pulled over. Finally I tracked it down and jerry-rigged a jumper wire past the ignition switch and made it to Colorado. I'd unhook it and hook it up at every stop and replaced it as soon as I got back Oklahoma. Problem solved. I hope yours is this easy. Good luck.

When it cuts out, does the tachometer continue to function?

I had a similar issue and noticed the tach going to zero. Turns out the tach wire from the disty in the engine harness would short out. Disconnected the tach wire and it never would cut out. Ran a new wire to fix the issue.

Relay board shorting as the board heats up? I had one fail at the fuel pump relay. Check it with a multi-meter or just swap it out and see what happens.

My money is on the fuel filter or the tank sock ...

I don't have a tank sock any more. I have a carburetor fuel filter in line in front of the pump. And both were replaced yesterday.

We just drove it to the grocery store. Still having the problem, but I spent most of the trip wiggling the key. Still can't make it happen on demand.

One time it happened at light throttle. Maybe one injector going and it feels worse than it really is???

The relay board on an L-Jet car does nothing. I can run the car with no relays in the relay board. The L-Jet has the double relay mounted by the battery and I already replaced it.

The tach never twitches when it happens, either.

Did you try cleaning the ends of the fuel pump fuse? Just a little buildup of crude can cause occasional failure

Fuel pump fuse on the relay board is not used with L-Jet.

Is this all on the same tank of gas? What grade fuel is in the tank? Consider as gas gets cheaper, the big guys at the refinery are going to consider ways to maintain profits. What additives are in the fuel this week? I started running Super in my cars 3 weeks ago, and noticed a remarkable difference in temperament just running around town. Consider getting a fuel additive for the current tank of gas, in order to increase the octane.

It happened at the tail end of a tank of gas. I filled the tank and added stuff to dry out any water thinking it might be condensation or some ethanol absorbing water.

And we always run premium in her car. 2.0 flat top pistons with 1.8L heads makes it a requirement to keep from pinging.

Seems like a pretty comprehensive list Clay. Did you see Rich's post early on about the ignition switch though? Have you ever changed it, or know the age of the switch?

Does turning anything else on have any impact, i.e. lights, etc?

If so, have you checked voltage at the battery while the car is on?

I highly doubt it's a fuel thing - just doesn't sound like those symptoms. Fuel pumps usually die, or work, not much in between. And if it was fuel starvation from a clogged filter or sock you'd expect the car to run fine for a little bit, then start dropping cylinders... then leave it for a few minutes and it runs find again until the missing starts again shortly after.

Run a jumper around the fuel pump relay and drive it.

My first thought would also be a electrical issue somewhere.

But you say you have no fuel sock, Have you ever had the tank lined?
I had an issue years ago where the liner came off in a sheet and would lay down right over the fuel outlet. Figured it would move off then get sucked back down after a few miles.

Tps

Time to drag out the carbs

I had the tank out replacing the fuel pump. While I was doing that, the gas gauge quit working. I pulled the sender to both check in the tank for debris and to diagnose the gas gauge. The gauge was a broken wire, and the tank was clean inside.




L-Jet has a 3 position throttle switch. It has one set of contacts open at idle, and another set a WOT. It won't be a problem at cruise, and this can happen at steady state driving on a smooth road.



With my wife, that will NEVER happen. Her car, her rules. She even got mad at me one time for putting a sticker on her car without her permission.



Thanks to everyone for their ideas. I am going to change both the ignition switch and the injectors next.

You changed the distributor, did you change the cap?

I had an issue once with it cutting out, and randomly not starting after coming back from going shopping. It was a bolt that had been left too long, and after about 3 years of rubbing on a red wire to the map sensor, it would cut out. Shortened the bolt, and fixed the wire, and problem disappeared.

Might try to replicated the problem, as in wiggle wires, and such while it is running it that helps to dertermine anything??

Didn't change the cap, rotor or wires. But I can try that tonight.

.....I had symtoms similar to those with a few 1.8's.......Check the *resistor
pack* & the wire's to the double relay.....peace

probably not your problem, but one time with a 240Z, I dumped a bottle of carb cleaner in the tank just to realize as i tilted it that the cardboard stuff under the cap was still stuck to the long neck...just as it disappeared down the filler neck. Every time I'd get below a quarter tank, it would intermittently get sucked over the fuel pickup in the tank and the car would not get fuel. Sometimes it would just run badly; others it would run completely out (3 Webers). Had to pull the tank to finally solve the problem.

Hmmm....mine was a pinched hose under the tank.

Resistor pack, injector harness and double relay have all been replaced.

Clay- disconnect the fuel line at the tb and stick the line in a bottle then have Betty turn the ignition on for a second. You should get a good flow which will rule out clogged line, pump, filter, crap in the tank, vacuum lock.

Did you try grounding terminal III from the rear of the relay board ? This will eliminate the relay connection and wire- this test helped me the most.

Also, forgot this one; is the relay ground wire firmly attached ? I've knocked this loose when reaching in to clean the case.

I may have missed this in all the posts, isn't there a ground wire for the breaker point mounting plate?? I had that break on an MG, took a while to figure that out..

Been over the whole fuel system. Replaced the pump, both fuel filters and all 4 injectors. Pulled the fuel sender and inspected inside the tank with a flashlight.




The relays on the relay board do nothing for the fuel injection on an L-Jet car. I checked the grounds under the intake 3 times now.




I swapped out the distributor.


This morning I pulled the steering column apart and replaced the ignition switch. Tried to start the car and it wouldn't crank. Put the old switch back in and it would crank. The brand new in the box ignition switch is bad. I have to go buy a new one on Monday. So I hung the wires below the dash, and used a screwdriver to turn the electrical portion of the ignition switch. Drove it around the neighborhood beating and wiggling the switch and the wires. No correlation between that and the cutting out.



Update on what has been replaced:

1. Air flow meter
2. Complete L-Jet wiring harness.
3. ECU
4. Double relay.
5. Dropping resistors.
6. All 4 injectors.
7. Cylinder head temp sender.
8. Distributor, complete with pertronix unit (tried a set of points too).
9. Distributor cap and rotor.
10. Plug wires.
11. Fuel Pump
12. Front fuel filter in front of the pump (substitute for tank sock. The car doesn't have one any more and hasn't had one for years).
13. Rear fuel filter.
14. Opened tank and inspected the inside. Nothing visible inside.
15. Added dry gas to remove any possible water in the tank.


Trying right now to replace the ignition switch too.

Rather than throwing parts at it, the only clue is that is goes lean with every interruption. What could cause that?

Have you monitored fuel pressure and is it constant? You have replaced all the parts, but what if the fuel pump circuits are intermittent? Have you cleaned your grounds lately? The fuel pump ground on a 74 is under the relay plate. How clean do all the electrical contacts look? Tried DeOxit on every connection?

How about the coil, they can fail intermittently.

How about the spark plugs?

This thread is like a mirror image of mine, only it's d-jet not l-jet. But I also see mine going lean when it's cutting out intermittently.
My next step is plug wires,

Clay, I've read over this and have a question on some things I don't see. Does this happen at a certain power setting? Does the physical location have any effect? I assume your elev is constant in that area.This is reaching but I found this in an aircraft once. The fuel hose had a soft liner which had a torn spot that allowed this same liner to act as a flapper occasionally and almost always at WOT, read take off!

Ok.. I have determined what is causing it.

It's the alternator.



While I was out test driving it earlier, in my head I heard my father saying "What was the last thing you f***ed with?" My dad almost never used profanity, so when he did, it made an impression. I remembered that just before this started, I replaced the alternator with a fresh bosch rebuilt one. So I pulled over and disconnected the alternator wires from the relay board without turning the car off. Took off again, and it didn't cut out at all.



Stopped and hooked the alternator back up and it started to cut out again.




Tomorrow after work I am going to replace the alternator with one I just had rebuilt by a local re-builder. Then I will go through everything I messed with just to be sure nothing else is broken, messed up or otherwise out of whack.


I still don't know why the alternator would cause the injection to cut out. Maybe some kind of voltage spike or blown diode sending reverse voltage to the ECU?

Thanks dad.

Since the problem is related to the charging system I would swap in another regulator before pulling the alternator. Why did you change the alternator to begin with?

I changed the alternator because it stopped charging. Before I changed it, I did a full field test on the old one. It would not charge even then.

Fro those that don't know, you can jump battery positive power to the field wire on the alternator. That will cause the alternator to charge max output. Don't do it for long, because you will burn up the battery. But it is a good test to see if you have a bad regulator or a bad alternator.

Thanks to everyone who offered suggestions on this. I appreciate the help.

That's why I suggested looking into the charging system early on in the thread... Glad you found it...hopefully

What a saga, hope this is the cure.

I'm late to the party here, glad it's working at the moment. I'm having trouble on how the alternator would cause the Ljet to quit working, seems unrelated

Both D-jet and L-jet require a minimum voltage, and the voltage needs to be pretty constant.

The Cap'n

Oh, it's around 11v, maybe 11.5, IIRC. Been a while since I looked it up.

The Cap'n

100% agree with you on the low voltage situation, but he re-started the car every time the engine cut out. If the battery was going flat, enough to drop out the Ljet, then he would of needed a jump every time, which is a detail that I didn't read in the earlier posts.

I know from personal experience that the D-jet will work pretty decently until the center console voltmeter drops below 9V. I don't know what the actual system voltage was, but when things got low enough the engine would die every time I hit the brakes. It also cut out in time with the lights when I used my turn signal.

I almost made it home that time... Got about a half-dozen blocks away and then a light turned red just before I got to it.

--DD

Cap'n,

The alternator is charging. I get 14.1 Volts at 2k RPM when it is hooked up. I suspect it is a blown diode causing a reverse voltage spike.

Is the belt tight? Is the alternator well grounded?