Sudden transitory power loss

[Akasharaja]

Hey everyone, greetings from this side of the pond!

I have a transient power loss issue in my ‘72 Bay. Three times now there’s been a sudden noticeable power loss, where the engine doesn’t cut out straight away but will no longer respond to the throttle; the dash lights don’t go on until I stop, at which point the engine stalls. I then wait for a few seconds, fire him up and off we go, no problem. There’s been the suggestion over here that the fuel pump might be starting to go, but there are no other obvious symptoms. Or might it be the coil starting to fail? Any suggestions grateful received.

[pioneer1]

I'd start with clogged fuel filter and or fuel line. Gas seeps past the obstruction to start motor but when you demand more fuel it can't deliver.
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[busdaddy]

A failing coil wouldn't suddenly recover after a few seconds of sitting, I'd be looking around for someone to borrow one of those snake style inspection cameras off of, sounds like there's a floatie in the tank.
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[Akasharaja]

Thanks. I did wonder about the fuel filter letting through little bits of crud that temporarily block the key before being flushed though. The current filter was only fitted last year, and I haven’t don’t that much mileage, but worth a look

[Akasharaja]

Jet, not key!

[mikedjames]

I would also check for things like the mechanical fuel pump pivot pin falling out or almost falling out, as well as a filter blockage.

An adhesive label off an aftermarket fuel tank level sender can create this symptom too, floats around, blocks the outlet as the fuel pump sucks it down. You stop and it drifts off as the fuel pump stops sucking. Drive on, no problem until it floats around again.



And if you have an electronic ignition module, these can sometimes fail with age (anything from straight out of the box to years..) and they can become very temperature sensitive.. slow down, airflow changes around distributor, distributor warms up slightly. Electronic module overheats. You stop, it cools down, restart engine, keep driving, no problem...
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[Akasharaja]

I’ve just remembered that I do possess an endoscope and will take a look in the tank - floatie theory sounds plausible.
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1972 Bay window bus, partial engine rebuild in 2022, new alternator same year, electronic ignition module.

[Nicholas D]

I don't know if it's the same with a '72 but my '71 has the sock filter inside the gas tank at the outlet. Not sure if that's the filter you mentioned being fitted last year but if not, don't forget about that one. It has been said by many that this filter can be omitted entirely if you're running an in-line filter further down the line.
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71 Westfalia
73 Beetle

[Akasharaja]

The filter i mentioned is an inline filter. Easy to replace. I don't know if there's an outlet filter in the tank, which was new 5 years ago. Would that be a standard part?
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1972 Bay window bus, partial engine rebuild in 2022, new alternator same year, electronic ignition module.

[busdaddy]

[Abscate]

Little more diagnosis needed

Next time you feel the power loss, quickly drop the clutch and see if the lights come one right away. I ll bet they do.

Leaving the clutch engaged means the motor is still turning over and the lights will stay off, even though the engine has 'stopped'
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