backfire through carbs?

RJMII · 10-25-2007, 11:31 AM

I am checking out a 914 in Salt Lake via email, and the person that has it sent this to me:

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heres the story. the 914 was my daily driver for 5 years in Seattle and Minneapolis until i bought a new car. i didn't need the 914 any more so i took it in and had it serviced and had the valves adjusted in preparation of selling it. when i was driving it home, it backfired and caught the right air-filter on fire. i shut the car off and it sat for months while the insurance was being figured out. it hasn't turned over since. i have replaced the carburetor but never taken it in to find out why it wont run.
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OK, why won't it run? where should we look?

I've done searches on backfiring, and so far I've come up with it being a valve issue, but this happened just after a valve adjustment.

Joe Ricard · Joe Ricard's Garage

Valve adjustments can be done wrong.
Doesn't run now because something was burnt through by the fire? Ignition????

RJMII · 10-25-2007, 01:01 PM

Joe, good point! thanks.

They might have adjusted it while it was still warm, which could lead to the chain of events that were just described.

Nostril Cheese · 10-25-2007, 03:06 PM

check...
timing and distributor
valve adjustment (do this with engine COLD)

what kind of carbs?

RJMII · 10-26-2007, 09:13 AM

It won't turn over... so the engine is locked up for some reason. I got more details in another e-mail.

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thanks for looking into it a bit. do you think a bad valve adjustment keep the engine from turning over? the other thing that makes me question that theory is that in the 15 miles home from the shop, it ran better than it had for a long time. on the other hand, this was a new mechanic to me that hadnt worked on the engines before but said that it was no problem. hhmmm?

i have asked a couple of other vw mechanics what they thought. one of them didnt have a clue. the other thought that maybe when the air filter caught fire and the carberator began melting that it allowed alot of liquid gas to enter into the firing chamber that couldnt be fired. his theory was that the piston compressed the liquid and when i shut it off there was enough compression that it wouldnt allow the engine to turn any more. the problem with that theory is that when i took the spark plugs out, i couldnt find any gas.
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I'm waiting to know what kind of carbs...