Replaced AFM. Starts but stops again

[busdaddy]

Sounds like you have confirmed continuity with the flap test when the key is on.

Is the spare AFM a rebuilt unit?, or used and removed from something else? If used it could have been on an engine with chronic vacuum problems that some "expurt" fixed by F'ng with the AFM adjustment. Now that it's on a (supposedly) non leaking engine it could be far too rich for it to stay running.
Here's a little test to see if it's in the ballpark: https://www.thesamba.com/vw/forum/viewtopic.php?t=442112&highlight=afm
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[Tejo23]

[Tejo23]

TS1 test is good.

[Tejo23]

[busdaddy]

Wow, that's set up really lean, could be part of your problem.

Does the lid look like it's been off?
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[Tejo23]

The lid has come off. It's loose.

There is a paint mark om the wheel:

That's painted by the previous owner I presume?

I'm thinking I will do the following:

1 test the load to open the flap of my original AFM (xx grams)
2 set the spring of the spare AFM so it will just open at the same amount of grams
3 test the spare in the bus.

Frank

[busdaddy]

Souds like a reasonable plan, it's clearly got problems as is.
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[SGKent]

In the thread I created with the weight on a NOS never touched AFM, I had another one that was not behaving right. I put the weight exactly where it was on the NOS one and the other one tuned exactly right, and passed smog with near perfect numbers - not too lean, not too rich. Just a tiny bit lean. I suspect that the factory used a wind gauge to set those but the way I did it was the best I could do. I'd lower the pressure to open it and see if it behaves close to properly. You still may have to tweak it but it sounds like someone played with the wheel. There is also the slider. Has it been tampered with?

FWIW the only paint color I have seen used is yellow or white on those. Blue may be a rebuilder who played with it. Who knows. That said, I bought a rebuild one directly from the factory and had to take it back.
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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

[ev_vw_dreams]

You've likely checked this but is the flap itself solid and closing right? Ran into a similar run and die issue on my cal bus with the AFM only to find out that one of my AFM's flap had a big hole in the center of it that was causing the issue.
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1979 FI CA bus
First time VW'er

[SGKent]

[Nitramrebrab72]

How much end play do you have on the AFM flap shaft. ???

[Nitramrebrab72]