"Dave Plowman (News)" wrote in message
...
In article , Julian
wrote:

"Dave Plowman (News)" wrote in message
...
I've asked on uk.rec.cars.maintenance without much success so fall
back to the experts.;-)

I've got a problem on the old Rover with the one way valve in the
petrol pump failing. It's a fuel injected car so has a high pressure
pump mounted underneath and close to the tank. There is a filter after
the pump and a gauze one inside the tank which I'm told often fails by
falling off. ;-) So what I need is a 1/2" fitting in line filter to go
in the rubber hose between the tank and pump - there's plenty of room
for near any size and shape within the transmission tunnel behind the
pump.

I'd question the wisdom of fitting a filter in the location you suggest.
At the most you don't want any more than a strainer because positive
displacement roller cell (is this correct?) pumps don't like to suck,
and given the low vapour pressure of modern fuel it will cavitate and
make noise.

Indeed - hence my mention of a low pressure one.

I don't think you understand the problem. The question is one of pressure
drop or delta P. It has nothing to do with the mechanical strength of the
filter - ie 'a low pressure one.' Any filter (unless it's the size of a
dustbin for your application) will cause too much restriction or pressure
drop. You can get away with a gauze or strainer but that's your lot.



But, many manufacturers don't even bother with even a strainer between
tank and pump, so why fit one? I suspect you suspect that there's crap
in the tank? IMHO you should remove the tank and clean it out and
forget about fitting strainers.

I think you'll find all tanks have a gauze filter internally.

No, (for instance) Audi deleted the tank strainer 1/2 way through one model
production - car equipped with K-jet and L-jet. No problems result
whatsoever.

And I've
read reports that most pump failures are due to dirt entering them.

Odd reports! Most expire through normal wear and tear. They slowly become
noisy and pump current consumption increases.


My
tank did have a gauze filter but it's broken off - hence the desire to
replace it with something similar externally. Specialist ones specifically
for this are available but expensive.

Do as you wish, but you're barking up the wrong tree.

Julian.