So went up to the 2cvGB committee meeting today, no problems on the way up, the van sat at 62mph without issue and same story on the way back... until...

I pulled into a service station for a nap and kipped for about 45 mins.

The last 50 odd miles it misfired, coughed, backfired (I think, loud bangs from exhaust system or possibly in the air filter?). So I limped home at 45ish, didn't fancy recovery.

Observations:
Worse in 4th gear
Worse above 46mph
No loss of power
OK on hills
No smells of burning, petrol, anything untoward.

Helpful info?
Plugs are probably 2 years old as are leads and coil.
Points, condensor and timing last done in September.
Fuel consumption is good - 220 miles on a tank
Pinks a bit if laboured up hills

Any ideas?

Shit in the carb, shit fuel, air filter blocked or something similar
Why plugs so old ??

did you fill up at the petrol station sam?

Sam,
if it starts fine and runs OK at lower rpm or with 'less than wide open' throttle, it could be the main jet partially blocked or reduced delivery from the fuel pump.

If it's misbehaving at other times, the condenser might be beginning to fail.

ken

That's interesting because she took ages to start last night, although she was fine this morning. I didn't fill up today, I put £30 worth of Shell 95 in her last night, was pretty empty but given the time between fill up and the issue occurring (100 miles?) I don't think its shite in the fuel.

Interestingly, that hesitant hiccouping was reminiscent of the time I had carb fail.

Can I check the fuel pump? I guess disconnect it and turn her over?

I'll whip the front off the points box too, I have a velleman unit that I must get round to fitting. Could it be oil in the points box too?

If you ran it low you could of sucked some shit up from the bottom of the tank. Can take a while to block sometimes

James.
about the nth time of saying this, but the intake for fuel pickup in all A series tanks is situated near the bottom of the tank, so running the tank low won't make any difference.
If there's any water or muck in the tank, it's just as likely to be picked up when the tank is full.

The only setup which runs the risk of drawing debris from the bottom of the tank into the fuel supply is on those motorcycles which have their reserve supply fed from a point lower than the normal supply...

ken

This wouldn't be the first time you've had carb trouble after getting that place to refurb it, Sam.

Ken
Surely the chances of sucking up any crud in the tank increases as you run lower?

No, but the carb issues I've had have been nothing on what they were before. I will make the carb my first point of investigation though.