75 Baywindow Bus starts but stalls when I let go of the key

[marc_music_mich]

I'm new to the Bus Life and let's just say that I'm not a machanic .. (that's one of the reasons why I bought my Westy... to learn hahaha)

This winter, my bus would start well but when it got hot, it would die. But if I gave it gaz, it would run no problem. (talked to my mechanic, he's convinced it's the tempII sensor). I looked at it with a mutli-meter and it gives me 53k ohm....This is probably the problem. The new sensor is on it's way and probably arriving this week. So I'll be able to change that soon but in the mean time:

This afternoon, I tried to fire up the bus and it does start but as soon as I let go of the key, it dies. If I keep it turned all the way to starting position it keeps running. This did not happened before... Even when I give it some throttle, it dies immediately.

Any ideas on where to look? What is the problem? troubleshooting tips?
I'll keep you posted when I change the TempII sensor if anything changes... Is that sensor related to my key problem?.

Thanks

Marc
75 Baywindow westfalia

[Jeff Geisen]

Use a jump wire from positive battery to positive coil and see if she stays runnin’. If it does continue running time for either ignition switch or hack in a toggle switch.
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I Corinthians 4: 1 thru 5

‘63 ragtop - ‘68 single cab

[SGKent]

what Jeff said. The run and start positions use separate circuits inside the switch. Also check to make sure you have fuel pressure. The pump gets its energy from the solenoid circuit as I recall when it is in the start position but gets it from the double relay in the run position. If the fuel pump dies when you let go of the switch that would cause it too but it would slowly die instead of instantly. My bet is the ignition switch because when it gets hot it grows a little in size and that can be enough to cause a bad contact inside it to fail.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[marc_music_mich]

Thanks guys.. Tried the bypass and it did not work. Changed the temp sensorII nothing changed.

When I turn the key, I see a yellow oil light on my dash that so that probably means that switch is working (that same light turns on when I plug battery straight to coil).

When I turn the key (on run not start), should I be able to hear the fuel pump turn for a half second or so? What would be the reading if I put a multimeter on the coil or the fuel pump with the key on run and the key off. I noticed that it doesn't smell gaz when I try to start. (the engine turns but doesn't start anymore)

BTW it is now 19 Celcius out now and the van doesn't start at all now haha. Any advice? (probably send it to a mechanic hahaha).

[marc_music_mich]

[SGKent]

you can disconnect the distributor wire from the coil temporially not to burn the coil or points, remove the cover on the air cleaner, and use a screw driver or chop stick etc to push the AFM flap open. With the key on when you do that the relay should click and the fuel pump should run.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[marc_music_mich]

ok so... we checked the fuel pump and it runs, checked if we have fire and we have. Checked the double relay twice it I think... it should be fine (followed Bentley's double relay troubleshooting) Tested the coil, it works fine.

Anything more we should look?
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75 Bay window Bus (Clementine)

New bus owner
Not a mechanic and trying to learn!

[SGKent]

[marc_music_mich]

[marc_music_mich]

[danfromsyr]

i'm not sure this applies to your 75 AFM
but in my later model AFM there is a set of contact points for the fuel pump
the fuel pump would get energized while key turned=cranking via the double relay. the wire that comes from the starter to the double rely.
then when the key is released from cranking
the AFM is supposed to have air flowing through it keeping it open and the contact points contacted.

well on ours they stopped wanting to be contacted, tested the misfunction with a small clip to join the contacts and it'd stay running.
tried making some tweaks to the contact wires but eventually just set up a simpler fuel pump relay from the IGN signal.

safety be-damned otherwise it wasn't going to run.
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[marc_music_mich]

here's where I'm at, Sent it to our local vw repair specialist and they did a ton of tests, looked at most of the wiring and everything is in specs... They did found a way to make it run by unpluging the cold start valve. It ran for about 5 minutes but very fast. They realised that the throttle wasn't going all the way closed so a little bit of lubricant and it made the job... but.. While doing this, the mechanic moved about 1cm a set of wires (I think it's the ECU harness) and it died (is is a coincidence? no idea)... So they did more and more test. Pluging or not the CSV doesn't seem to make a difference anymore ....

Here is what they think, before the ballast resistor, we should have 12V (that's what we have) and out, we should have 5 ish V. (we have 12V.... no load on the system) He says that the van should work even if we have 12V but not as good as it should.

He put a light on one injector and it does light up (2 small nodes and then it stops... wait 10-15 turns and same... 2 small nodes and stops)

He noticed that the light comes on stronger if he plays with the air fuel meter (he thinks when the AFM is open the light (injector) gets 12v instead of 5V thats why it flashes brigther).

Now I can't find a new ballast resistor to see if that is the problem...

Next step, he wants me to get myself a new distributor and trie it on... (mine is pertronix conversion and he wants me to change it back to points to see if that makes a difference)

Just a small recap... new spark plugs, new SP wires, new bosh blue coil, new temp2 sensor, new ignition switch. It starts but dies about 1-2 seconds later (if I left go of the key or not...)

Any other ideas before I start buying The whole Busdepot hahah!!!
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75 Bay window Bus (Clementine)

New bus owner
Not a mechanic and trying to learn!

[busdaddy]

I disagree with your "specialist", the resistor will show 12 volts on an open circuit, it's when it's under load that the 5v deal happens and most meters won't even show it, if it was making full 12v all the time your injectors would all be cooked.
How did they diagnose the distributor?, was there a repeatable loss of spark that wasn't related to any external issues or replaceable parts within it?

Both of their suspects are very simple robust devices that don't break in mysterious ways, they either work, or they are clearly broken in half.

Sounds to me like they have no idea what's going on and are shooting the parts cannon at it at your expense, time to find a new shop or buy a multimeter and learn to fix it yourself.
Sounds to me like a harness and ground problem.
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[marc_music_mich]

[busdaddy]

Sounds like you are well on your way to becoming a certified bus mechanic, the ability to research and learn is the first step!
Since something happened when a wiring harness was moved I'd start there, after that many years of heat and flexing wires can break internally or lose contact at the terminals even though they still look "fine" externally. An option to get it going fast is contact Kyle: http://kyleautomotivespecialties.com/ , yes it's a "parts cannon" move, but no old used harness is truly reliable and it's money well spent even if it's somehow not related to the current issue. If you are feeling more DIY' ish then here's lots of reading: https://www.thesamba.com/vw/forum/search.php?searc..._chars=200
Another simple thing to look at first is the ground cluster under the plenum on the case seam, they get dirty and loose and maybe bumping the harness disturbed something, FI can't work if it can't ground.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

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[marc_music_mich]

[marc_music_mich]

[busdaddy]

[marc_music_mich]

[ToolBox]