Stalling VW

[john2443]

1971 1300 Karmann Ghia (Beetle engine)

Start it, let it warm up, auto choke comes off, ticks over happily (sounds like a bag of spanners, but that's normal!)

Drive it, bloody thing stalls, particularly when slowing towards a junction it'll stall between 4th and 3rd.

Any ideas?

(It's a friends, not mine so I might not be able to answer questions!)

Thanks

[Zener]

Possibly a tuning issue/carb setting or sediment/moisture in the float bowl blocking the carb idle/pilot jet

[john2443]

Zener said:

Possibly a tuning issue/carb setting or sediment/moisture in the float bowl blocking the carb idle/pilot jet

Thanks.

I did wonder about that - it's just been to a garage who has supposedly got it running well, but the day after it was stalling.

[larrylamb11]

Carb icing would be another possibility - is the heat riser blocked on the inlet manifold? Is it the original carb & manifold or after-market? Is the warm air pick up still connected and working?

[Zener]

Not likely to see carb icing this time of year though

[griffter]

I’d check the timing and for air leaks. Slowing for a junction (engine braking) there’ll be a relatively high vacuum in the inlet.
Could be lots of things though! Fuel filter?

[larrylamb11]

Zener said:

Not likely to see carb icing this time of year though

Can happen any time of year - humidity is more relevant than ambient air temperature. The VW engine is a favourite to ice carbs, particularly if the air filter, carb, manifold or exhaust have been changed and / or the heat riser bypassed.

[Zener]

larrylamb11 said:

Zener said:

Not likely to see carb icing this time of year though

Can happen any time of year - humidity is more relevant than ambient air temperature. The VW engine is a favourite to ice carbs, particularly if the air filter, carb, manifold or exhaust have been changed and / or the heat riser bypassed.

Not IME in the UK it dont

[aeropilot]

john2443 said:

1971 1300 Karmann Ghia (Beetle engine)

Start it, let it warm up, auto choke comes off, ticks over happily (sounds like a bag of spanners, but that's normal!)

Drive it, bloody thing stalls, particularly when slowing towards a junction it'll stall between 4th and 3rd.

Any ideas?

Look for the Wheeler Dealers episode where Brewer bought an air-cooled VW that kept stalling when ever he pulled up at a junction etc.....think it might have been the VW Thing they did in USA on Edd's last series....?? I know it was an Edd show, as he was a bit of a air-cooled VW fan IIRC.

[lancer778544]

aeropilot said:

Look for the Wheeler Dealers episode where Brewer bought an air-cooled VW that kept stalling when ever he pulled up at a junction etc.....think it might have been the VW Thing they did in USA on Edd's last series....?? I know it was an Edd show, as he was a bit of a air-cooled VW fan IIRC.

Was gonna suggest exactly this. Skip to around 3:30 if it doesn't already start there:

[Zener]

fk me I've seen it all now when this bullst show is used for ref purposes

[john2443]

Thanks for the suggestion all.

Before I had time to go back and look the owner took it back to the garage (who'd declared it all good last week) who had another look and found an air leak.

[Ambleton]

One thats an absolute peach (and hasn't been mentioned yet) is a dodgy fuel cap.

It should vent, but occasionally it fails (fully or partially) and means the tank is pressurised as the fuel is drawn out. When running at some revs the pump might be able to fight the vacuum created and draw enough fuel to keep it going but it might be causing fuel starvation.

Quick one to check but has been the bane of a few people!