Gomog, I think you have somewhat misunderstood what I have been saying.. I fully agree with Bunny, Red Three and Planenut that the published fuel system diagram is wrong. The fuel flow is from the pump to the injectors and returns via the fuel filter.
That's ok Chris. (mona lisa smile) The great thing about mechanics is reality invariably rules. One of us will proven wrong anon. I am willing to believe that the MMC diagrams from their two parts books,
along with their detailed parts description and my own understanding is incorrect M3W are different.
https://www.ls1gto.com/threads/walbro-255-pressure-bleed-down.323614/. My guess was that the multi-purpose pump-sender-strainer houses a check valve (which has failed as so many of them do). Does anyone of you have that assemblies maker and model? Easy to check then
(PUN!). Is this the one?
https://morgan-kent.com/product/fuel-pump-m3w/ It's unavailability suggest that this is a common failing.
My WALBROs never came with a check valve. It is good to hear from you that to know that they do now. I will keep searching to find one.
gmg
