'78 Super Beetle, unidentified wires, engine stalling

See if they go to the Diagnostic Socket (if you have one). There is info on my web site here:

Find out if the pump *actually* runs after the engine starts. A contact in the AFM keeps the pump On . See the Fuel Injection article on my web site:

You need to get *some* kind of measurement on the pump. Either pressure (gauge on the Cold Start) or voltage on the pump wires (hard to get to).

If you dare, take the air inlet connection off the AFM. Use a soft probe to move the air shutter. With key On, that should make the pump run (listen or feel the pump).

2500 is at room temp. At 30F, 6500 may be correct.

If that was 30C, then the sensor is bad.

Follow it back to some clue.

Speedy Jim

"I have no use for a car which has more spark plugs than a cow has teats!" Henry Ford, when advised that Chevrolet was introducing a 6-cylinder engine.

Probing the MAF shutter does make the fuel pump run. There is a bad connection on the fuel pump wires underneath the back seat on the driver's side. Sometimes this makes the double relay switch on and off when flexed. When it is connected properly, i.e. the shutter in the MAF makes the fuel pump run, the car does the same starting and stalling. The contacts in this connection have been cleaned but continues be unreliable.

OK. Let me see if I understand correctly.

You have identified an unreliable connection. I would do whatever it takes to make that reliable again.

Next: If there is still a problem starting, try this: Hold the vane slightly open with the probe as you start the engine. This will not only run the pump but should make the mixture somewhat richer. Hopefully, it will be possible to make the engine run for longer time. This is merely to prove that the engine CAN run of its own.

Since this has been an on-going resto project, is it possible that the fuel in the tank has gone "stale"?

Does this include cutting the connection plug off and wire nutting the two ends together, or is there a reason that the plug is there. Are there less invasive and irreversible ways to solve this connection problem that I should try first?

The stale gas shouldn't be a problem. The fuel tank and filter and pump and lines have been replaced and I only add about 2 gallons from a 2 gallon can whenever I run dry in the tank. The gas can's gas is fresh too.

I can't really try to probe the air intake flap until I fix this connection and am assured that it is not flipping the fuel pump on and off when I try and start the car.

I wouldn't hesitate to cut the plug off if it can't be made reliable.

I replaced the connection with 3 radio shack spade connectors so it is now reliable.

I probed the air intake flap and the fuel pump runs when I do.

When I hold the flap open and someone starts the engine, it dies the same as every other time.

The one ground wire that was unlabelled goes to the license light, though the hood is off at this time.

The two white wires get bundled with everything else from the control unit and I've as of yet been unable to trace them. I know that the double relay has no extra spades they may have come off of.

The charcoal cannister, the cylinder in the passenger rear fender (I think), is not connected.

I've timed and re-timed the engine to 5 degrees ATDC like the Muir book says. I also have the Bentley manual.

I was wondering if it might be that the four main injectors were failing to fire while the cold start valve initially got the engine chugging. Might this be the case? If so, is there a good test?

It still has the original pressure regulator. Might this have gone bad?

I would:

1) Put pressure gauge (60 psi) on the cold start valve fuel line. Normal pressure is ~35psi. Anything near that will work.

2) Check for 12V to the ECU. Easy way is to measure voltage on the ballast resistor pack with key On. You can put meter on any of the resistor terminals.

3) Find out if injectors *are* being triggered. One way is to unbolt a pair and watch 'em squirt. That risks breaking the fuel lines. I would rather measure/observe the pulse to the injector plug. You may be able to see a small response on an analog meter (not a digital). Or a tiny 12V bulb wired across the plug.

I used a test light in all the injector plugs and they're all recieving current. (The light flickers)

Testing the ECU with key on showed 12V with positive on ballast resistor end and negative grounded (that's what you meant, right?)

Does this mean the injectors would be fine? Couldn't they still be clogged? The car sat in my Grandfather's garage for 15 years.

Also, could the valves be sticking shut after so long a time? When one pushes on the accelerator, the car backfires. I've checked all the vacuum hoses and they seem to be fine. After the backfirings, I made sure they were all reconnected.

As of yet, I have not removed the valve covers, the heat exchangers are new, so they shouldn't be contributing any possible back pressure from blockage.

OK. Electrical tests sound fine.

Yes, injectors might be clogged. (long shot) In the end you may have to pull one out and watch.

Test compression by hand. Turn the pulley (Alt) and see that the crank pulley goes 'round two complete revs. That will produce 4 firing strokes and you should be able to feel the 4 distinct compression peaks.

Spring for a brand new set of spark plugs and have a look at the present ones to see if there are signs of wetness (fuel).

Verify that #1 plug wire gets spark when #1 is actually on the firing stroke. When the rotor points to #1 wire, the Intake AND Exhaust valves for #1 must be closed (rockers loose). Pull the valve cover and check.

Go over all the hoses again. A backfire will usually dislocate *some* part of the intake. (You've already checked the vane, which is a frequent victim).

I tested the compression on Cyl. 1 and was fine.

The old spark plugs don't show signs of wetness.

The rocker arms for the valves were loose when cyl. 1 was at TDC

It looks like all the hoses are on.

On removal of the injectors. I removed the 10mm bolt that holds the retaining plate. Must both injectors on one side come out together? What is the metal pipe that connects the front two injectors (2 and 4)?

Oh, I figured that the metal pipe must be the return line that runs the fuel across the engine and back to the driver's side set of injectors. This said, how do I even use the injectors since I can't turn them over with the metal pupe pointing them down. Were I to remove the metal pipe, the injectors I'd be testing aren't getting fuel.

Well, the injectors are connected by a stub of flex hose. If you take them out, source the injector seals and new high-pressure injector hose beforehand to put things back. (I can almost guarantee the hoses need replacement after

1/4 century.)

I'm not convinced of the necessity to take the injectors out, though it's the most direct way to evaluate of course.

Before that, I would measure fuel pressure AND I would make a starting attempt with fresh, dry plugs. Pull the plugs after and see if they are wet/smell of fuel. Can even do the test with the cold start valve unplugged so it's not an influence.

A bit complicated, but you could run the pump briefly to pressurize the fuel ring (with gauge attached). Then trigger the injectors (without running the pump) and see if the residual pressure in the fuel ring drops off.

I did try to remove the injectors, but they are held so tight by that metal pipe (and I didn't want to spill gasoline everywhere) that I had someone turn the key and run the engine while I just held them about a quarter of an inch above their respective holes. (Driver's side injectors) They didn't spray any gasoline marks as far as I could tell, and this was with all the fuel connected.

I don't have a fuel guage as of yet, so those tests have to wait.

I replaced the spark plugs. Plugs from 2, 3, and 4 were wet. Plug from cylinder 1 was bone dry. I ran the engine with the new plugs and then removed plug from cylinder 4, it was wet again. Plug 1 could have been dry from me removing it for the compression test and having not really tried to run the engine much since then.

The cold start valve disconnected does not affect starting and stalling. the MAF disconnected does not do much to affect the engine performance either.

Get any kind of cheapo pressure gauge; doesn't need to be specially for fuel.

That was a good test with the injector 1/4" out.

If you can prove/disprove proper fuel pressure, that will point where to go next.

BTW, there is a treasure trove of FI info (and much more) here:

including scans of the Bosch manuals.

The site is aimed at the Type 2 Bus, but the L-Jetronic is the same as used on the Beetle.

What would it mean if the pressure was above 35 psi, and what would it mean if the pressure was below 35 psi. Would either of these conditions cause the wet spark plugs?

Also, the spark plug from cylinder number 1 is always dry, while that from cylinder number 2 is still wet. These are new plugs.

What pressure did you measure??

That *is* suspicious.

I would think one injector not injecting...

I'm going to test the injectors for internal gounding. In my question about pressure I was merely asking if the wet spark plugs might be indicative of too much fuel pressure. I replaced the coil and I now have the much covetted blue spark. For a one time use, the cheapest fuel gauge I could find was $37. Specifically, what would a fuel gauge tell me about my probems. Would it tell me the injectors were bad, the regulator was bad, or they both were fine.