Weber dual 40 IDF accelerator pumps not pumping

[nicks]

I've just fitted 2 new diaphrams but still getting no fuel out of the swan neck pipes down into the barrels.
There is fuel in the pump body (it leaked out when removing both pump cover and arms).
The symptom that prompted me to fit these was the fact that since owning the car for last 2 years it's always needed about 5 attempts to start when engine cold (independent of the air temp outside !). Once running it always starts again and always runs fine.

Can anyone advise next steps to solve the pump issue ? Could it be the pipes downstream of the diaphrams ?

Car is BS1 with 1608cc

Thanks !
Nick

[redcars]

Have you checked that the little holes in the end of the Swan necks are not plugged up. The holes are very small and will get plugged up over time.

[justrhines]

Could also be the check-valves that allow fuel to be sucked into the pump body from the float bowl, but prevent it from being pushed back into the float bowl. They are located inside the float bowl on the bottom- you can take them out and blow into them to check their operation.

Justin

[nicks]

Thanks both. I'll try the pipe and float ideas !