72 vw stalls when hot

[john riley]

I have just bought a 72 vw bug. It has a problem after it warms up it starts running bad and finally shuts off. the starter will not turn the engine when it is hot. let it cool off for few minutes or hour and it will crank and run for 5 or 10 minutes before it shuts off again.

[Doug Rodrigues]

Could be anything, but my best guess is that it sounds like the possibility of two problems:

1. The carb idle circuit is blocked. Once the choke becomes wide open, the idle mixture becomes too lean. You'll probably have to clean the carburetor out. One other possibility.....the fuel shut-off valve could be loose and leaking too much air at idle. Those things have a tendency to vibrate loose and elongate the threads in the carburetor. If you find yours loose, get some Red Lock-Tite to anchor it in. Don't overtighten it or you'll strip the threads out of the carb.

2. The starter is probably high time. If you remove the starter you will probably find brush material packed into the commutator segmets. This condition shorts-out the segmets and weakens the cranking power. Remove the starter, pull the armature out of the housing, break an old hacksaw blade into a point and clean what is supposed to be a slight gap between the commutator segmets. Clean all the way down (about 1/8 inch) to the insulator material until you get every bit of brush material removed. Get a piece of 300 grit (or so) of sandpaper and "shoe shine" the commutator segmets to knock-off any high spots. While you're at it, replace the brushes and stick some high temperature grease into the ends of the armature shaft bushings. Put it all back together and see what happends.

**Oh...I forgot to mention: Don't use emery cloth to "shoe shine" the armature. Particles of the abrasive will become stuck in the segmets and that will destroy the new brushes. Use sand paper only.

[john riley]

I thank you for the help. The car shuts off or quits running going down the road. It may be timing on the starter. This vw hadn't been driven much in the last few years because of this problem. The carb. had been overhauled a few months ago but still didn't fix the problem. I wonder if the valves need to be adjusted could be causing this problem. I also have a problem with the front seat loose. the floor pan was replace sometime ago and the seats have been loose every since. I can put the seat on the track and the first time the car stops or starts the seat will come off the track. Any suggestions.

[Doug Rodrigues]

If you're just cruising down the road and then the engine starts running rough and quits, then that sounds like fuel starvation. How's the condition of your fuel tank? Is there anything in there that can block the screen at the fuel pickup in the tank? Stick a small inside diameter clear plastic line down into the fuel tank. What do you see when you suck on the line? Is it gasoline or rusty looking junk? Is your fuel filter plugged? I'd at least remove the fuel connection to the fuel pump and blow into the line to confirm that it isn't plugged. What condition is the fuel pump in? Can you safely disconnect the fuel line from the pump to the carb and crank the engine over to check for fuel pressure? After 32 years, that rubber diaphragm in the fuel pump should just about be "shot." If you notice any gasoline smell in the oil, that would confirm a defective fuel pump.

If it just turns-off like someone turned the ignition key off, then it's probably electrical. That could be anything: Corroded fuses; loose wire at the fuse block; loose wire at the points; defective coil....anything. It's just something that you'll have to eliminate one by one.

What I mention above aren't a guarantee, but only educated guesses as to what the problem may be. A shop mechanic would simply eliminate each potential problem one by one.

On your seats: There is no way for an accurate answer from anyone unless they could look at it to anaylize the situation.

[kleky]

Im having similar problems with my 71 Beetle too. When the engine is cold there's no problems. Driving short distances around town is fine but get on the motorway or drive around for about 30mins, it starts spurting for fuel like being starved. It doesnt switch off immediately, but if I stop, it may cut out and never start again until cooled down.

The carburettor's had a clean so doubt its that. Ive had an idea it may be a fuel line with the filter on, being so close to the engine it gets too hot? Anyone else had this problem or know what it might be?

Many thanks for your time!!!

Ian

[ridge_runner]

maybe its running hot... hmmmm....

[kleky]

Really? you are a bright spark aint ya. Thanks for the help