914 Fuel Injection, Need an L-Jet Guru!! Options

[Cjllong]

I have a 75 914 with a 2.0 motor. It originally had a 1.8L, but I acquired a 2.0 from a wrecked 73 914. When the 2.0 was rebuilt and installed, the mechanic installed the 1.8L fuel injection system and told me it was superior to the 2.0L fuel injection system. I drove the car for 2 years and never had a problem. All of the sudden, the car wouldn't start. I took it to a local German auto mechanic, (The guy who originally did the conversion left town), and he said he would fix it. Well.... A new fuel pump, plugs, other stuff, and the big one.. a new computer, the darn thing still has the same symptoms. It simply dumps fuel into the valves when starting, causing it to flood almost instantly. He checked the fuel pressure regulator and it seems to be fine. He's telling me that the computer is holding the injectors open too long, causing excessive fuel to flood the motor. $1300.00 later, he says he'll do the rest of the diagnosis for free. I think I payed for his education of the 914 fuel injection system, and I don't think he learned anything. I originaly posted this problem on Pelican Parts and they directed me here and told me to look for Clay Perrine. If your out there, please help me! I'm desperate!

Chris

[dakotaewing]

I am sure Clay will post when he gets a chance -
He does travel quite a bit for his job, so just be patient and he will get back with you -
And by the way, he a Dave Darling are 2 of the best people to help -

TE

[bd1308]

Check the Air Flow Meter, they get stuck sometimes, especially if you've had some backfiring issues. The vane should be 'closed' when the engine is off.

Another thing is the cold start valve, if that stays open, it'll also dump fuel into the plenum, and subsequently (if it fills enough) into the runners and into your engine.

Ive had AFM troubles before on another 914 I worked on, although I did everything for free for another guy, out in the rain--needless to say I didnt work on it for a long time.

I would say start with the AFM, they are the most troublesome thing on the L-Jet, the computers 'rarely' ever go out.

In one day I converted a 2.0 bus L-Jet system to run on my 1.7L engine. Its a little fat at idle, but it sure does go!

[srthompson01]

I had the same problem, wasted many hours testing and the components all checked out good.

Turned out to be the wiring harness. Specifically the wire to the airflow sensor.

Good luck

Stephen

[Cap'n Krusty]

I take issue with the statement "rarely ever go out"........ They NEVER go out. Unless you maybe jump start with the cables on the wrong terminals, and maybe not even then .....................

Problem areas:
Air flow meter
State of tune, including the ever important valve adjustment.
Vacuum leaks, vc gaskets, oil filler (TWO seals, and the cork base gasket), intale manifolds at heads, and the 4 hoses on the runners
Grounds
Miswired TTS and/or CSV
Bad wiring harness
Charging voltage

See the following links:

http://www.vectorbd.com/bosch.html

http://www.forparts.com/techbosLjetronic.h...dle%20incorrect


The Cap'n

[newto914s]

I had the same problem, wasted many hours testing and the components all checked out good.

Turned out to be the wiring harness. Specifically the wire to the airflow sensor.

Good luck

Stephen

If the wire to the air flow sensor is disconnected the system will go to full rich. Was a great supplimentary choke this past winter on my 78 Westy running on 3 cylinders, but it could be causing the flooding. Another simple check of the air-flow meter is to put the key to the on position, don't start it. You should hear the fuel pump prime for a second then shut off. Then(still ign. on) reach into the airflow meter and push the air flap. As the flap is ingaged you should hear ether the Fuel pump start up again, or the injectors pulse. I can't remember which now, but you should here something when that flap it moved and the ignition is on. Lastly make sure the 3 ground wires under the passenger side intake runners are attached.
After the steep(and expensive) learning curve that is D-jet. I was really impressed with the simplisity and effectiveness of the L-jet system. It's the Air flow sensor or something is disconnected, that's it.
Good luck and find a new mechanic

[ClayPerrine]

I had the same problem, wasted many hours testing and the components all checked out good.

Turned out to be the wiring harness. Specifically the wire to the airflow sensor.

Good luck

Stephen

If the wire to the air flow sensor is disconnected the system will go to full rich. Was a great supplimentary choke this past winter on my 78 Westy running on 3 cylinders, but it could be causing the flooding. Another simple check of the air-flow meter is to put the key to the on position, don't start it. You should hear the fuel pump prime for a second then shut off. Then(still ign. on) reach into the airflow meter and push the air flap. As the flap is ingaged you should hear ether the Fuel pump start up again, or the injectors pulse. I can't remember which now, but you should here something when that flap it moved and the ignition is on. Lastly make sure the 3 ground wires under the passenger side intake runners are attached.
After the steep(and expensive) learning curve that is D-jet. I was really impressed with the simplisity and effectiveness of the L-jet system. It's the Air flow sensor or something is disconnected, that's it.
Good luck and find a new mechanic

This has a slightly incorrect statement in it. On a 914 (not a Westy) the fuel pump will not run when the key is turned on. It only has two conditions where it runs.

1. When the key is on and the engine is running with enough airflow to open the air flow meter flap.

2. When the key is in the start position the fuel pump runs. Check this by disconnecting the yellow wire from the starter and turning the key to the start position.

[ClayPerrine]

Ok.. on to the problem with the L-Jet.


I would look a few things...

1. Check the fuel pressure. Put a gauge on it. Then turn the key on and open the air flow meter flap. Make sure the pressure is at 32psi. I have seen an L-Jet system with a plugged return line create around 100psi. This will definitely flood the motor.

2. Check the cold start injector. Pull it from the plenum, disconnect the wiring, and place it in a jar. Run the fuel pump as described above. It should NOT leak any fuel. If it does, replace it.

3. Check the injectors. Pull them from the intakes and put them in jars. See if any of them leak via the same test as the cold start injector.

4. This one is the most unlikely, because you said it was running good then it quit. And in deference to the Capt'n, the computers are very, very durable. But I have seen an issue where 30+ years of vibration has broken solder joints on the boards in them, causing a poor running problem. This can be exacerbated by the replacement of the 914 L-Jet computer with the wrong year. If you plug a 75 computer into a 74 wiring harness, the contacts for the air flow meter are slightly different, and it will run extremely rich, causing flooding. The reverse is also true, a 74 computer in a 75 open circuits the AFM, causing a flooding condition.

Start with those things, and we can go from there if none of those are the culprit.

[rhodyguy]

$1.3k. geez...for that kind of money i sure hope a new air flow sensor gasket was installed too. the mech gives you a bill that size, the car still doesn't run right, and he can look you in the eye to tell you he won't charge you again for further diag? wtf? when do he and his wife leave for hawaii?

k

[PeeGreen 914]

I love mechanics who chuck parts. They make me look like a pro (IMG:style_emoticons/default/biggrin.gif)

[Cjllong]

Thanks to all of you for your input. I think I'm going to take your advise and pull the car from the mechanic. He's obviously not the expert I need. I'm not a total idiot when it comes to cars and I do have a decent shop/garage. I think I'll do the diagnostics myself and go from there. Keep the ideas comming and I'll keep posting on my progress! Thanks again and I should have come here first! I'm sure I'll be back with other issues though.

Chris

[rhodyguy]

if you haven't seen this give it a look. http://manuals.type4.org/ljet. i hope the mech returned all the "used parts". mutiple fuel pumps....

k

[bd1308]

Cap'n....

Never say never

[JeffBowlsby]

Thanks to all of you for your input. I think I'm going to take your advise and pull the car from the mechanic. He's obviously not the expert I need. I'm not a total idiot when it comes to cars and I do have a decent shop/garage. I think I'll do the diagnostics myself and go from there. Keep the ideas comming and I'll keep posting on my progress! Thanks again and I should have come here first! I'm sure I'll be back with other issues though.

Chris

Thats the spirit! That is exactly what this place is about Chris. Its not that hard to learn the FI system or anything alse about your 914, you will be knowledgeable about your car and have more $$$ to spend on that stuff that really counts...

(IMG:style_emoticons/default/welcome.png)

[Cap'n Krusty]

I had the same problem, wasted many hours testing and the components all checked out good.

Turned out to be the wiring harness. Specifically the wire to the airflow sensor.

Good luck

Stephen

If the wire to the air flow sensor is disconnected the system will go to full rich. Was a great supplimentary choke this past winter on my 78 Westy running on 3 cylinders, but it could be causing the flooding. Another simple check of the air-flow meter is to put the key to the on position, don't start it. You should hear the fuel pump prime for a second then shut off. Then(still ign. on) reach into the airflow meter and push the air flap. As the flap is ingaged you should hear ether the Fuel pump start up again, or the injectors pulse. I can't remember which now, but you should here something when that flap it moved and the ignition is on. Lastly make sure the 3 ground wires under the passenger side intake runners are attached.
After the steep(and expensive) learning curve that is D-jet. I was really impressed with the simplisity and effectiveness of the L-jet system. It's the Air flow sensor or something is disconnected, that's it.
Good luck and find a new mechanic

This has a slightly incorrect statement in it. On a 914 (not a Westy) the fuel pump will not run when the key is turned on. It only has two conditions where it runs.

1. When the key is on and the engine is running with enough airflow to open the air flow meter flap.

2. When the key is in the start position the fuel pump runs. Check this by disconnecting the yellow wire from the starter and turning the key to the start position.

It doesn't "prime" on a VW, either. The systems are, for all intents and purposes, identical. The Cap'n

[Cap'n Krusty]

OK, I'll never say "never". It's so rare as to be statistically insignificant. BTW, a shorted injector, just one, will keep 'em all open, all the time. But then, it wouldn't run at all. The Cap'n

[bd1308]

Either way, the computer shouldnt have been replaced....

Which is where I was going (IMG:style_emoticons/default/smile.gif)