Massive engine problem

Have you got a soft-start system on the engine? If so, could it be switching the timing?
What happens if you engage the choke during the rough running?

Could you run a temporary fuel supply into the carbs using only gravity feed? Use new hoses and a T-piece to enable you to eliminate the complete existing fuel supply system including the pumps, filter, etc.

Kevin Stewart wrote:

Have you got a soft-start system on the engine? If so, could it be switching the timing?
What happens if you engage the choke during the rough running?

Could you run a temporary fuel supply into the carbs using only gravity feed? Use new hoses and a T-piece to enable you to eliminate the complete existing fuel supply system including the pumps, filter, etc.

I'm unsure about the softstart. But I changed the boxes and there was no effect.

Gravity fuel supply I could  run with some effort. But I don't see the point. I changed the pump, I blocked the return line, so there should be no issue fuel related (I think...). In general the fuel system in the CTSW is a bit gravity driven as well beside the pump. 

Christian

That cable tie holding the fuel hose to #1/3 carb looks plenty tight. Is it possible that is restricting supply? 

Have you removed the banjo fittings to the carbs and checked for debris between there and the needle valve? I read on a different thread where a small flake of paint was stuck in this area and causing similar intermittent problems that you describe.

You may have a restriction anywhere after the fuel pressure sensor.

If it's not that, I would check the throttle slides and circlips to make sure the slides aren't binding, and the mixture needle doesn't change position (this is not uncommon).

Murray Parr wrote:

That cable tie holding the fuel hose to #1/3 carb looks plenty tight. Is it possible that is restricting supply? 

Have you removed the banjo fittings to the carbs and checked for debris between there and the needle valve? I read on a different thread where a small flake of paint was stuck in this area and causing similar intermittent problems that you describe.

You may have a restriction anywhere after the fuel pressure sensor.

If it's not that, I would check the throttle slides and circlips to make sure the slides aren't binding, and the mixture needle doesn't change position (this is not uncommon).

Tha cable tie compress only the fire sleeve, it's not that tight...

If there is debris inside the fuel line the engine wouldn't run in warmer conditions I guess. I removed the banjos several times when I replaced the carburettors. Plenty of fuel came out of both and should washed out any potential debris.

The throttle cables I renewed as well and both works very very smooth.

Chris

Chris,

Can you reproduce this problem with the propeller control in the manual position?