Problem with loss of power and lack of time

Type 1 engine, all stock except for a powerspark electronic dizzy, recently rebuilt original solex 34 pict 3 carb.

I'm getting intermittent loss of power when I open the throttle. It's weird, I drove for 2 hours on Saturday and it didn't happen once but it's been happening for about a month now and it's doing it again this evening.

I'm thinking it's a fuel issue which is clearing with revs but that's just my feeling and I'm no expert. It's the intermittence of it and the fact it appears to clear with revs that got me thinking that.

As I rebuilt the carb in the autumn and have checked the idle jet I'm not sure it's there, like dirt clogging jets, but I could have made some mistake somewhere with the rebuild. I also haven't yet checked the fuel filter that is clipped under the tank.

Thing is I've got limited time to look at it before I start a 500m round trip to Norfolk on Thursday. Any ideas or better yet a time efficient elimination process?

Thanks,

Max

 

does it have a thermostat & flaps? perhaps sticking causing overheat?

 

First things first - change the fuel filter ....

 

Don’t fuel up at the local supermarket


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Filter
Air leaks

 

Ditch the powerspark

 

^this.

 

I had a similar issue on a type 4 motor a while ago. Turned out to be the powerspark dizzy. I refitted the original with a pertronix module & all was good

 

I'm running an original SVDA dizzy with a Powerspark module with no problems so far, touch wood. The trouble with the full electronic dizzy is they are cheap Chinese ones so that mighg be the cause. If you can find a conventional dizzy and try it with that you might at least be able to eliminate.

 

Is the Powerspark electronic distributor a 009 clone? What coil are you using?

 

Ok thanks for the responses. I should have time to put my old 009 back on and change the fuel filter this evening.

 

If you fit a 009 expect to have a flat spot.

 

Most issues perceived as a fuel problem will in fact be electrical related - so check condenser coil rotor arm etc

 

All the electronic points replacement modules can fail because they can get mega hot. You get hiccoughs, rev limiter effects..

Accuspark seem to recognise this by providing a sachet of thermal grease to install under the module. Then it at least has the base plate to act as a heatsink.

When they fail, even another of the same brand will work reliably in its place.
My score :

• Pertronix blown up leads swapped. Replaced with half price (of Pertronix) Accuspark module.
  
• Coil failed, flashing over, replaced generic with Bosch.
• Accuspark "failed" but it may have been the coil.
• Coil failed, bought another Bosch

Still running Accuspark. About 70k miles with about 30k since last ignition failure.

 

My bus is off the road with just this sort of problem.

Twice in one day (whilst trying to get away on holiday with the family of course) lost all power when pootling along happily on a the M3. Pulled into the hard shoulder. Engine would rev freely at a standstill but as soon as I engaged 1st and tried to pull away again .. completely flat.
My regular VW garage were very helpful. We got their on the back of an AA lorry, and then spent a couple of hours swapping out various ancillaries {coil, condenser, dizzy} and test driving.

Thought it was resolved with the replacement coil. We set off again for Cornwall. Got back to almost the exact same spot on the M3 and broke down again in the same way.

Abandoned planned family camping holiday in Cornwall.

Bus is still in the garage. Clock is ticking before Goodwood Revival now ...

 

Are you running std points & condenser& dissy? I had an Accuspark dissy which gave the sane symptoms your explaning. I think the advance mechanism played up when it got hot

 

Standard points, condenser and dizzy. I have a Petronix electro ignition dizzy but I haven't install it yet.

The news is though ... it's sorted. Replaced the alternator and disconnected my leisure battery setup which is apparently a poor implementation and needs rethinking at some point in the future.

 

That sounds a bit odd. I would be surprised if that's it.

 

If the alternator does not charge the battery properly, then the battery voltage would drop until it loses spark power.

However this could also be a fuel feed blockage or the fuel pump is not working, gravity feed through the pump works until the pressure from a topped up tank drops off and the bus will not have enough fuel to run.

Did you top up before each trip ? .


Too tight valves could also do, or a loose rocker arm shaft , it takes half an hour for things to warm up completely, then you lose power as the valves leak, or stop opening if the rocker shaft is loose.

 

Fuel pump also replaced! I forgot that.