Injection issues?

[Beancounter]

Hello I have lurking about for some time now and would like to thank everyone for sharing their knowledge. I have a recent problem with my 81 westy. It fires up immediately and dies just as quickly. It acts as though someone turned off the key immediately after it started. This problem just started, the van was running fine prior. Subsequent starting attempts with different throttle positions doesn't help. I haven't tried holding the AFM open when starting though, my arms aren't long enough. No excess gas odours. Checked for vaccuum leaks, and ignition problems. I have used the search function but haven't found a topic with this exact problem. Can someone direct me to a thread or suggest a troubleshooting process.

[Tram]

Double check ALL of the vacuum thoroughly ALL hoses and fittings. Make sure the intake boot is tight, and not cracked. This has "vacuum leak" written all over it!
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[Randy in Maine]

I also like the S boot that Tram mentioned. They split on the underside where you cannot see them until you take it out and hold it in the bright sunlight.

Also make sure you check a couple of electrical connections:

1) The ones on the top of the starter that go to the double relay.
2) Make sure the double relay is grounded well (even if you have to run a new ground wire.
3) Also check to make sure that the injectors grounds (under the air plenum and there are 2 of them) are properly grounded to the grounding plug terminal in the case halves.

Could your ignition switch be at fault?

Also have a look at the brake booster vacuum hose at the engine and also at the booster unit.

[Beancounter]

Thanks guys for your responses. I replaced all vacuum lines with new rubber last night (even though no cracks found in old ones) and checked the seal of the S boot (its brand new). From cold it started right up. I warmed it up and took it for a 10min drive. It seemed to run fine except it cut out going up a slight hill. Then the recurring starting problem happened. Starts immediately then cuts out immediately. If I held the starter on after it had lit, it would continue to run as long as the starter was engaged. I didn't do this for long. I eventually roll started it going downhill. That started it no problem. Back home in my driveway it would do the start immediately then die syndrome. The next morning it started fine. Tonight I will check what Randy suggested. Any other suggestions.

[Randy in Maine]

What kind of fuel pressure and volume are you getting?

[Beancounter]

Thanks Randy I think you've nailed it. I will test it tonight but I can't hear the fuel pump humming with the ignition turned on.

[Beancounter]

Still no positive outcome. Engine starts then dies, Will start and remain running if roll started. When running engine performs great. Lets review what I have done. New vacuum lines, verified S boot, cleaned double relay ground and the 2 injector grounds.
Fuel pump test: volume 1.8L/60sec,
Pressure test:
1) ign on, manually open AFM results 2.9bar or 40psi
2) starter engaged, AFM disconnected 2.9 bar 40 psi.
After roll starting engine, running @ idle
-with vacuum to pressure regulator 2.5 bar 35 psi
-without vacuum 2.6 bar 37 psi.
The Bosch manual says 2.2-2.6 bar 30-37psi.
Leakdown test 28psi remaining after 30 min.
The problems happens hot or cold so that should rule out the cold start valve. Tested when warm - not spraying.
Someone please verify my thinking, have I ruled out fuel delivery issues?
I don't think the AFM, double relay, injectors or ignition is an issue because the engine runs fine when rolled started.
Help. Where do I go from here? Not on a road trip, that's next weekend!

[Randy in Maine]

OK I have a couple of ideas. I like to start with the free ones.

Minimum voltage to be in the game is about 9.6 volts so make sure your battery is charged up. Check it with your volt ohm meter.

Also keep in mind that I don't have a Bentley manual for a Vanagon, just mine from my Baywindow. They are pretty close, but not exactly the same. I am stealing most of what follows from there, so be warned if it looks familiar.

Use your volt ohm meter to test the resistance in the Temp Sensor II over by #3 cylinder. At 68*F you should be seeing resistance in the range of 2000-3000 ohms. At 176*F you should be seeing resistance in the range of 250-400 ohms. You are mostly looking for the change in resitance from cold to hot.

If you have a stethescope (I don't - I use a long screwdriver or a piece of heater hose) you should be able to hear the injectors buzzing or clicking as the engine idles. They should all sound about the same.

Try removing the wiring plug from the ECU and from the back o fht eAFM and clean both sides with your contact cleaner from Radio Shack. OK, now with our Volt Ohm Meter:

Termials 36 -39 Stator flap closed = no continuity; slightly open = continuity. BTW, that flap should move freely.

Terminals 6 - 9 (potentiometer) 100-300 ohms
Termianls 7 - 8 (potentiometer) 80-200 ohms
Terminals 6-27 (temp sensor I) <2500 ohms

With the engine idling, pull off that black cap on the AFM and look at how it works. The curved needle on the right is what shuts off the fuel pump when the car rolls over. If you move tht needle gizmo to the left the mixture get richer until it bogs out and to the right it get leaner until it starts to run crappy. Make sure the needle is able to freely move right and left. Also make sure there is not a bald spot where it "rides" on the circuit. No spray in there though. I just know enough to be really dangerous.

Assuming nothing has jumped out at us so far, I am thinking that your fuel pressure regulator is not quite right. Are you using the water pressure gauge from HD? Somebody told me that gauge is +/-4%. Keep that in mind.

To check the FPR:

Engine off, key on. Nothing in the AFM. 35 psi +/- 2psi (2.5bar)

Engine idling. Nothing in the AFM. Gauge should read 28 psi +/- 2psi (2 bar).

Same set up, remove the vacuum line going to the FPR, pressure should rise (quickly) to 35 psi +/- 2 psi. (2.5 bar)

You are high all across the board. When this thing sort of chokes out is it from being too rich? Plugs rich, carbon in exhaust pipe, poor fuel economy?

Try this, remove the fuel line going back to the tank after the FPR and hook up a hose going to a gas can. See if the pressure drops back to what it is supposed to be. If it does, the fuel line retun to the tank is somehow plugged or kinked and is the problem. Otherwise it is the FPR.

If you have a spare FPR or a friend ( I think they are the same from 76-83), now would be the time to try it to see if that helps out problem. A new one is about $100 though.

Other possiblities are that there is a intake vacuum leak (does the AAR test out correctly?- that 90 boot in the bottom always seems to have a split in the bottom of it), fuel injectors faulty or clogged, or the cold start valve is leaking or running all of the time, or the thermotime swtich is not happening right.

Let us know.

You will know all about this FI system when you are done won't you?