Engine sputters and dies when at high rpms and under load

[bavArian]

Hello everyone,


2 weeks ago the A ran fine, but in the last few days I've been having a problem with the engine.

Current conditions: ~50 fahrenheit ambient temperature, dry, fuel has max. 5% ethanol in it and is fresh





When driving under high load and at mid to high rpms it tends to die while driving with missfire from the exhaust. If I lower the rpms, the engine stays on most of the time but I can't accelerate anymore. It's especially bad uphill. If it stays running I get missfire and a bad throttle response, making it impossible to keep moving. If I stop the engine and let it sit for a while or remove the drain plug of the carb and screw it back in (fuel running from the carb obviously) it usually starts right up and runs fine for a short time.



I've done/checked the following things:


- filled the tank to 3/4
- checked for a steady stream of fuel from the sediment bowl, looks good
- disassembled the car, everythings clean (jets as well) and gaskets are in place
- checked the float, it's the right height above the upper housing and moves freely
- cleaned fuel strainer
- float valve seems to work fine if carb is disassembled
- gas cap tight or missing doesn't make a difference







It idles perfectly but will make problems when it's running above what I guess are 1200 (??) rpm. Downhill/level roads with low revs are no problem.



Am I correct that it's not getting enough fuel? I've read that the float valve can work fine if the carb is disassembled but cause problems when running? I don't know how old the float valve is but I assume ->very<- is the correct answer.



If that's unlikely, what else could it be? Ignition seems unlikely because why would it run well for half a minute or so before making problems?


Hope that someone can guide me in the right direction.


Greetings from Germany,


Daniel