Loss of power and backfiring help?

[chickensandkids]

Have a 1.9 watercooled 1985.
Recently had new Weber carb. Been running lovely, but return of old problem.
After running for say, half an hour (to pub) on way home, after being stood for an houir or so, began to lose power and run lumpy.

The only time you can get power is if you floor it - full throttle.

Stopped at traffic lights, ticks over but can't pull away without flooring it. Backfiring. No Smoke.

Could this be fuel system, or ignition? any tips - Bug Jam Next weekend!!!!!!!! Don't want to arrive on trailer!!!

[Mocki]

sounding like a fuel starvation thing to me..... replace filter, of which you should only have one, under the sill near the tank.. remove any extra ones in engine bay.
when you had the new carb put on all the petrol pipes shouold have been replaced, but if not you really should.
check for cracking on pipes, because if they are cracking on the outside, they are on the inside, and deliverying bits of crud to the carb.

also check the tank filler for holes, as its common to have a filler pipe thats got a hole in it and water sprays up off the wheel and you end up with water in the tank, which you will see in the filter...


could also be the pump failing, or the pump pushrod worn.

[chickensandkids]

Cheers Steve.
Again Runs well but will warm her up and see. Great to be able to bend your ear about it -
Cheers again. Dave and Sarah