New to Vanagons and abruptly shut off on me. [SOLVED]

[donjordan]

Hi all,

I bought a 1985 vanagon (digijet) a couple months ago and I had a sudden loss of power a couple weeks ago while on the freeway. I've been following diagnostic procedures but need a little help.

PROBLEM

I was driving on the freeway and after driving ~30 miles the engine just shut off. Almost like a switch got flipped. While I was waiting around for the tow truck I decided to try to start the van (about 30 minutes after initial shut off) and it started up. It ran great so I decided to drive the rest of the way to my destination. Later that night I was driving home and after approximately 30 miles, the same thing happened. I waited thinking that maybe a component was getting hot and needed to cool down but I could never get it going again. Towed home.

WHAT I KNOW

The engine is getting enough air and it does have spark (it will fire if I spray starter fluid in the intake). I have hooked up an oscilloscope to the fuel injectors and cannot see a pulse while cranking. This is my problem, but why? Based on research, the ecu sends pulses to the injectors based on the hall effect signal, but since there is spark I assume that the hall sender is operational.

Also, fuel pressure is ~31 psi.

WORK DONE SO FAR

After doing research on this site and elsewhere on the internet, the problem to me seems to be electrical. I started by cleaning all of the ground connections, replacing TempII sensor, ignition switch and took a gamble and had the ecu rebuilt. It still does not run.

QUESTIONS

Is bench testing the AFM a good indication of its performance during normal operation? I measured the resistance of the wiper strip, air temp, and applied an external voltage to measure the wiper voltage output. All looks good, no drop of voltage anywhere.

Another thing that I was looking into was the hall effect sensor. According to what i've read, I should be seeing 0 to 2V minimum as the engine turns over. I am measuring 2V to 7V. This is out of spec but I'm getting spark. Does the hall effect sensor control spark or fuel, both?

Thanks!

[Ahwahnee]

I had a similar failure and it was a relay that heat got to. It would cool down and work again but I replaced it before it got to the point of total failure.

In my case it was the fuel pump relay - but since you have pressure that is not your problem. But there is another relay right next to it in that same black box:

I'm thinking that other one (the outboard one IIRC) is for the ECU. You might confirm it is okay (or not) with a simple substitution if you have a spare or by jumpering the socket if you don't.

[Californio]

In my experience, the AFM doesn't usually cause a sudden failure like that. They wear down and you get Vanagon syndrome (coughing, bucking, etc.) but not usually total failure to start.

A failed Hall Sensor or a broken wire to it could cause the symptoms you're talking about,

[Californio]

Well no, actually--if it started again when cool, probably not the Hall Sensor.

[RicoS]

[edgood1]

make sure the computer is getting a good ground.
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[Hammy1]

I too had issues with one of the relays. It would run fine but when I shut it off it wouldn't start until it cooled down. I also wasn't getting injector pulse during cranking. It's worth a try.......

Regards'
Jon h.

[donjordan]

UPDATE

I installed a new hall sensor tonight and she started right up! Thanks for all of the insight.

Don

[T3 Pilot]

Excellent news,.

I had a similar experience and resolution...

http://www.thesamba.com/vw/forum/viewtopic.php?p=7984468
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The most important part in every vehicle is the nut behind the wheel......

[ftp2leta]

We have another thread going on... please change your title to SOLVE.

I read the whole thread for nothing

Ben
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[RicoS]

[donjordan]

[RCB]

[JustsomeKentuck]

Perhaps he wasn't being rude, but was just making a suggestion. IDK, but it didn't seem rude to me.
Perhaps a Smiley Face Emoji and everyone wouldn't of gotten so worked up.
Ah, the Internet. Hard to judge intention in such few words.

[EverettB]

Thanks for adding a SOLVED thing to the title.
This is nice sometimes.

Don't worry about the comments above, sometimes it's hard to know people's intents from text.
In general I assume the best of people until I discover otherwise.
This has served me very well in life.
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[djkeev]

[ftp2leta]

[RCB]