Spitfire Spitfire 1500 won't stay running

[philkenealy]

Spitfire 1500 with Weber carb starts easily and runs until the throttle butterflys start to open, then dies. It will start again if the carb is primed but dies unexpectedly. Fuel is being pumped out when fuel line is disconnected from the carb while the engine is running so it appears the fuel pump is working. Where should I start diagnosing?

 

[Sarastro]

I'm not familiar with the sidedraft Webers used on the spitfire, but I am quite familiar with the (downdraft) Weber IDFs that are used on VWs and Porsche 912s. So, this may or may not be relevant, but since no one else has answered, I'll give it a shot.

Since it starts and runs at idle, it's not ignition. Since the car dies when you open the throttle, it seems that it has to be a carburetor problem. I would look at the various jets to make sure nothing is plugged; the jets on Webers get plugged very easily. Do you have a fuel filter on the fuel line from the pump to the carbs?

I'd look especially closely at the accelerator pump jets. If one or both of those are plugged, the mixture leans out when you open the throttle and it can stall the engine. It's possible that the idle and progression jets are plugged, too, even though you are getting enough fuel through them to keep the engine running at idle.

 

[NutmegCT]

+1 on Sarastro's suggestions.

Also, how long have you owned the car? Was it running normally when you got it? Was anything changed or "adjusted" recently, that might have caused the problem?

Thanks.
Tom M.

 

[sp53]

I am not familiar either with your set up, one thought I had was the distributor advance might be involved. If you get the car moving down the road, will the car accelerate evenly as the rpm increase?

steve

 

[Malcolm Cook]

If your carb has a manual choke, , engage, if the problem seemes to be cured, dirt (blocked )main jet

Malcolm Cook