Intermittent Problem with Betty's car, I am at my wit's end on this one. Options

[ClayPerrine]

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 (IMG:style_emoticons/default/WTF.gif) stage, and looking for suggestions.

[r_towle]

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.

[Tom_T]

Clay, that sounds like an intermittant bad connection or wiring break....the 914 descendants of the traditional "old VW electrical gremlins"! (IMG:style_emoticons/default/biggrin.gif)

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.

(IMG:style_emoticons/default/santa_smiley.gif)
Tom
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[jim_hoyland]

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

[ClayPerrine]

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.

[r_towle]

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.

[JeffBowlsby]

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?

[eyesright]

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.

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.

[Spoke]

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.

[rick 918-S]

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.

[SirAndy]

Maybe its fuel related? dirty tank sock? dirty fuel filter?

(IMG:style_emoticons/default/agree.gif)

My money is on the fuel filter or the tank sock ...
(IMG:style_emoticons/default/popcorn[1].gif)

[ClayPerrine]

Maybe its fuel related? dirty tank sock? dirty fuel filter?

(IMG:style_emoticons/default/agree.gif)

My money is on the fuel filter or the tank sock ...
(IMG:style_emoticons/default/popcorn[1].gif)

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. (IMG:style_emoticons/default/headbang.gif)

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

[ClayPerrine]

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.

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.

[PanelBilly]

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

[ClayPerrine]

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.

[dakotaewing]

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.

[ClayPerrine]

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.

[ThePaintedMan]

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.

[rick 918-S]

Maybe its fuel related? dirty tank sock? dirty fuel filter?

(IMG:style_emoticons/default/agree.gif)

My money is on the fuel filter or the tank sock ...
(IMG:style_emoticons/default/popcorn[1].gif)

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. (IMG:style_emoticons/default/headbang.gif)

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

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

[Mark Henry]

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.