I'm trying to resurrect a 75 1.8 thats been sitting for 15 years. (she was hiding in a basement next to the furnace for all that time). Pretty darn rust free as far as 914's go. She got parked for FI issues.



I'm trying to get her running again. I've got the tank clean. The fuel pump was cleaned and runs. The fuel injectors have been cleaned and checked, click well. Dual relay clicks when attempting to start. She turns over, but I'm not getting power to the fuel injectors. What to I try next?

Thanks,

Your story is very much like my '74, with mine it was 3 injectors sized/dead. The pintle is moving right? All grounds cleaned? hoses hooked up correct and no leaks? seal on oil fill cap?

There is a tool called a "noid" that will verify if you're getting power to the injectors. It's a little light that plugs into the connector to the injector. Try Harbour-Freight for an inexpensive kit. Did you try some sort of starting fluid to see if it would fire on that?

No broken wires at FI Relay Pack??

another key to the L-jet fuel injection is the Mass Air Flow sensor...this is the that large module that the air box bolts onto. If you take the top cover of the air box off you'll see a big flap that regulates the amount of air entering into the system. It opens up simply by the air being drawn into the system by the engine cranking/running. Key point is it is what triggers things like the fuel pump starting to run etc. If it sticks, power isn't sent to those (I'm guessing you are not hearing the fuel pump running also?). A few easy tests to do (on top of using the noid tool mentioned above):

1. spray a little bit of quick start into the air box...if the car runs for a little bit then you know you are getting spark and not fuel
2. crank the engine and manually push that air flap open on the MAF sensor...if it is sticking and the air doesn't have enough force to open it up on it's own...no power to fuel pump etc. If it starts you know what it is!

BTW.....nice find! That car looks like it is in really great shape!

Actually, the fuel pump is activated during cranking by the double relay, not the air flow meter. During cranking there is not enough air flow to open the flap, so the pump won't run.

Pull the yellow wire off the starter, and turn the key to the start position. You should hear the fuel pump run. If you don't, you probably have a bad double relay. Second, check the wiring to the dropping resistors. They have a tendency to break at the bottom, and then you will lose that cylinder. If enough of them break, then the car won't start. A noid light will verify this real quick. Just pull the plugs off to each injector, and have someone crank the car while you watch the light. It should flicker during cranking.

Another thing to consider -- the Ljet brain requires a signal from the switched side of the coil. If this wire is disconnected, the injectors won't fire.

I have continuity to the resisters and they show about 5.9 ohms on the bench to each one. Wires look good. Voltage to ground showed .2 volts when turned on. Didn't move when trying to start.

Checked the contacts of the relay by a little careful surgery. Nothing melted or missing. Both coils move. Continuity looked good. Tried to trace their paths best I could. I'll see if I can get a new relay on order, will take a few days.

Everything looks to be hooked up.

Fuel pump runs when attempting to start, got voltage at the pump and can hear it running.

No fire when I sprayed starting fluid in the system and tried to crank.


Hi Mike!!! Happy to be here.

Clay...info I got was from a Porsche mechanic who helped me get my 75 l-jet sorted. The AFM completed the circuit (according to him) and it needs to open just enough to allow the pump to run (relays, afm etc are all in the loop). He was dead on as the test we did with him there was open it alittle and behold..the pump started. His explanation was porsche did this so as not to have fuel being dumped in without air. I'm no expert here but this came right from a Porsche mechanic and he demonstrated the fuel pump not running when cranking and the flap close...and the fuel pump ran when opening it slightly. I saw it with my own eyes. Maybe the 75's are different but that is what I saw.

Now, back to this issue...you said you used starter fluid with nothing happening. You should have gotten something here since the fuel delivery system would have been bypassed. Is there spark/sufficient spark getting to the plugs? You said that you could hear/feel the injectors clicking...do you smell fuel? Have you tested to make sure the fuel supply lines have not been accidently hooked up in reverse?

Next step I'll check the coil and plugs.

When I said injectors clicked, that was testing on the bench after they were ultrasonically cleaned.

I tried starting with the vane of the afm open, no change.

Fuel lines are clean and correct direction. Fuel filter is not blocked.

It should be easy enough to put an inductive timing light on a spark plug wire, crank the engine and look for flashing out of the timing light. Either that or take a spare spark plug and one of the plug wires and ground the threads of the plug and crank and look for spark. Sounds like you have fuel and no spark.... You can do a visual of the cap and rotor and verify the wires are connected in correct firing order in the distributor.

point gap/dwell?

I agree. Sounds to me like you don't have a functioning ignition system. And remember, if the coil isn't getting switched, the Ljet ECU ECU won't trigger the injectulators.

So no spark AND no fuel.

I too am thinking you don't have a functioning ignition system which as previously said results in a non-functioning injection system.

Try starting the car while jumping the + side of the coil with a wire coming directly from the + terminal on the battery. This jumper ensures your ignition/injection system is getting power. If your car starts the problem is with your ignition switch.

Just make sure you try starting immediately after jumping the coil or you could fry your points.

Timing light shows no spark....lets see what I can find now....

Can't get power to the ignition. Jumpered a wire to the + side of the coil, nothing. Even tried a spare coil.....

Put in new points tonight. I now have power at the coil. Plus side on at start, other side flashes on my test light. Timing light shows spark at each plug wire, but slowly.

I put my test light on one of the injector plugs and it showed constant on at start.

Not showing power at fuel pump now.

Tried jumping 12v to the fuel pump, got fuel circulation noises at the regulator, would not start still.

Now that I have spark, I'm wondering if I have something wired wrong, or if the relay is now bad. Bosch platinum plugs are installed, figure I'll put some standard plugs in too.

Back up. Pardon me if I am brief...
We need to extablish that you have a functioning system.

Remove large hose from throttle body and AFM.
Turn key on to run position.
Stick finger in large hole of AFM and open the flapper door.
Does the fuel pump come on then...with all standard wiring? (no jumpers)
If no, check fuel pump relay...the smaller relay pack next to the tubular relays for the injectors.

Post a pic and someone should be able to point to the relay for you.

Second
When key is on, you should see 12VDC on the middle pole of the tubular FI relay pack.

Third, open up the distributor cap, remove the rotor and look at the advance plates. We have been finding the small ground strap that connects the advance plates has seen better days...sometimes it looks good but it sucks. weak wire= weak spark.
Also, your coil may be suspect.

Lastly...
Go to the store and buy four baby food glass jars.
Empty them and clean them
Pull all four injectors and while leaving them hooked up to the fuel rail, place the ends of the injectors into the glass jars.
Remove the high voltage wire that goes from the coil to the middle of the distributor cap.
Turn over the car for 30 seconds.
See how much, if any, fuel you have in the glass jars. It should be the same amount.

RIch

Good plan Rich, thanks, I'll start again.

Also check the 2 fuses on the relay panel. I believe one of those is for the power to the relay's and the other for the fuel pump? Since they are exposed they get corroded very easily.

I have been doing this (and living with a L-Jet equipped 914) for 24 years, and I had factory training from VW on the L-Jet system. Your mechanic is partially right. The air flow through the air flow meter should trigger the fuel pump. But when you are trying to start the car, there is not enough air to consistently trigger the fuel pump. So they have the circuit tied to the starter circuit that causes the pump to run when the engine is cranking. It does not run when the key is in the on position, only when it is in the start position. If you don't believe me, take the yellow wire off your starter and see if the pump runs when the key is turned to the start position.




The fuses on the relay board are not used for the injection on an L-Jet car. You do not need either the fuses or the relays on the relay board.

Are you sure about the relays on the board? I too had an Ljet that had been parked for a year because it wouldn't start. I went ahead and cleaned the blue 25 amp fuse closest to the firewall (didn't help), the other fuse is for the rear glass defogger if equipped.

However, the last relay (closest to the firewall) is part of the equation. When I changed mine out with a known good one the car fired to life instantly.

Does someone have this picture for a 75 1.8 car? Or can tell me the differences?

The factory workshop manual shows 3 relay boards, the last one for a 73. I would then guess that 73-76 are the same.

Sounds like pure coincidence to me.

I am 100% positive about this. Betty's 914 has not had a relay on the relay board for years. She doesn't have a heater hooked up, no heated rear window, and no D-Jet. And it runs just fine.

The relay boards for all years of 914/4 cars were functionally identical. I assume there were manufacturing changes because there are no electrical changes to the board.

My 74 Ljet has only has two relays and one does run the heater. Clay I know you know the in and outs of Ljet very well, but I'm pretty sure my L-jet has to have at least the one relay to startup and run. You have me curious now. I'll have to pull my two relays and see what happens. Even though when I cleaned the blue 25 amp the car still just cranked and cranked, perhaps it was a delay re-action. It's been a long time since I've had an L-Jet.

You shouldn't need the fuse either. All of the power for the L-jet system comes from the power feed wire that runs between the double relay and the battery.

To understand how the double relay works, read this.

Super!

Thanks,

Clay is correct here. The Ljet system pulls its power directly from the positive lead of the battery, bypassing the fuse on the relay board.

The Ljet wiring is a poor design for a number of reasons; the main one being: IT HAS NO FUSE. I strongly recommend adding an in-line fuse to the double-relay battery supply lead.

I just replaced the loop on the end of the wire with a fusible link that already had the loop on the end. Now I don't worry so much.

Didn't make it past step one. No pump running when I move the vane in the AFM.

I tested the relay best I could. I could make both coils click, fuel pump contacts had continuity.

I do have 12v at the resistors.

Wire on the advance plate is in good shape.

you stated that the fuel pump runs when you run it off jumpers, right?

The main coil pack should have 12vdc at the middle pole.
The fuel pump relay is in a small unit next to the tubular ones.
Does that one function?

Rich

Sounds like the contacts on the double relay are bad. Do you have another you can try?

Tested power at the pump this morning. I got power to the pump while attempting to start, and it was going through the relay. (should have also checked the afm at the same time, but was trying to get out the door to the office, I'll check that again tonight to see if I just couldn't hear it)

12v was also at the center pole of the resistor pack.

I can start to smell fuel at the tail pipe.

A change of spark plugs is in order also.

As far as I can tell from wiring diagrams, from manuals, and from working on my own 1.8, none of the relays on the relay board are needed for an L-jet car to run. Just for the heater blower and the rear defogger.

(In fact, that was a MUSR tech quiz question one year.)

--DD

Still trying to start the motor without success.

I know I have mis-matched injectors right this second, but was going to fix that soon.

Right now I have 3 from a 912-e and one of the original 1.8's. I have a nice set of 1.7's on the shelf....

Trying to understand from what I've been reading, are L jet and D jet injectors not compatible? I saw the flow rates the same for the 1.7's vs the 1.8's, so I thought....

(BTW, I'd trade the 1.7's for 1.8's if someone was interested)

If I remember pulse rates are different so not interchangable 1.7 to 1.8.....it's a Djet vs Ljet thing. I bought NOS Ljet injectors from AA last year for around 55 each when chasing down a rich running problem I was having (see below that injectors was not my problem). I have the injectors that I replaced that are very usable as is and would be in great shape if cleaned.

There are others smarter than me that will chime back in I'm sure.

My experiance with 75 1.8 Ljet Relay talk above is this. When I had Relay's in my relay board FP ran all the time. It was in a 72 body so I assume earlier relay board. FP was running so much I was thinning out my oil because so much gas was getting by rings....ouch (and that 1.8 is still strong as an OX).

Good Luck

Ken

This morning, I broke down and sucked the smidgen of gas out of the tank and replaced it with 4 gallons of nice fresh super unleaded. Checked all was still hooked up and turned the key.

After several attempts I got a pop. Kept trying and she fired.....

IT IS.....ALIVE!!!!!

She only ran a few seconds, so I tried again with the same results. Fuel pump runs when starting, but does not continue. I'm leaning toward the AFM, should have a buddy bringing one over tomorrow to test the theory.

Turn the key on and open the flap with your fingers. If the pump doesn't run, you have an electrical problem. If it does, you have a problem somewhere between the throttle body and the Air flow meter. My bet is the oil cap seals. If they are bad, the car won't run... makes a big false air problem.

Okay, I'm getting close. One the phone last night tracing lines with a buddy, then looking at the wiring diagram for the relay this morning got me thinking.

Starter circuit of the relay works to the coil, but not the ecu side, the one going through the resister. I check for resistance and continuity through the relay on terminal 86b and get nothing, soooooo resister should be bad.

Anyone know the value of that resister? Maybe I can hit the shack this afternoon and replace it.

Ah the web is a wonderful thing....

John; With ign on, you should have 12v to the injector plug. If so, your resistors are good. The ECU signals the injectors by grounding that circuit.
Good luck
Randy

Picked up a handful of resistors at the shack this afternoon, had to assemble a few to get close to 2.7 ohms. Did some careful microscopic soldering, then plugged everything in. Hit the flap on the AFM and heard the fuel pump come on...

Turned the key to start and after a few seconds she came to life.....

Thanks for all the help guys!!!

Time for some tires and brake lines and she'll be on the road.

Here is the offending resistor.



and my temporary fix..

Sweetness John! Good to hear you got it running again.

You know I've got an extra set of shoes over here if you want to get away from the steelies. Lots of Yokahama rubber on them.

Click to view attachment

Mike

Where exactly is this resistor located? I also have a '75 1.8 liter that sounds like its doing the same thing - I can get it to fire, but it won't stay running...and tracking down electric issues is surely not something I'm good at.

BTW, did you find this car in the VA Beach area? I saw one that looked similar that was advertised not to far back - very nice.

The resistor is in the fuel pump relay, circuit from pin 20 of the ECU.

Car was in the Winston Salem area where we found her.

Wow... fixing a resistor in a relay,

You need to buy a replacement double relay, if only for piece of mind.


Congrats on getting it running.