V8 with SU carbs losing power after about 20 minutes drive

My V8 with SU carbs losing power after about 20 minutes of driving.

Everything is ok in idle, and it fires up very well from cold.
After app. 20 minutes of driving it seems too lose power, but when i choose a lower gear (from 5. to 4.) it is ok.
When i am slowing down to turn, it loses power when i am speeding again, it goes down to idle and i have to wait app. 30 seconds before i can slowly shift to 2. and 3. and so on without the engine jumping.

I have changed the gas filter, and cleaned the carbs and the swimmers and so on.
it has a 1 year old gas pump.
new sparks and i cleaned the wiring from the pump.

after app. 10 minutes it can run for 20 minutes again.... very odd problem?

Have you a blocked fuel tank breather??(blocked vemt on fuel cap etc)that will cause your problems

zen said:

Have you a blocked fuel tank breather??(blocked vemt on fuel cap etc)that will cause your problems

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i already did this, i drove with the fuel cap off, and nothing changed.
there is lots of fuel going to the carbs, i did a clean due to overflood of gas, and after the cleaning the overflood has stopped.

is your coil getting hot when its playing up



Just a wild stab in the dark

Sounds like fuel. Pump is the most obvious, and worth checking electrical connections, a bad joint heats up and goes high resistance, stopping the pump. Cools off, and off you go again.

Peter

I changed the coil and it solved the issue.

have you checked your not running a 9v coil without a ballest on a 12v system ,thus knacking it

sounds like its fixed