fuel pump queery

YouTube · Post by **El_Freddo** » Tue Aug 23, 2011 2:49 am

SUBIIE wrote: Now the engine is going the pump runs but makes this, dare I say it, cavitating noise almost constantly, at least for the first couple of minutes.

What should I do, or is there something I have done very wrong?

I'd probably look at making a surge tank and fitting that. There are some down sides to a surge tank but the up side is that you can thrash all day long and not starve the high pressure pump.

Here's a DIY surge tank - I couldn't just drop the image in here as I'm on the work computer tonight

Cheers

Bennie

SUBIIE · Post by **SUBIIE** » Thu May 10, 2012 9:25 am

So, as far as I can understand.

run the standard carby fuel pump to the surge tank

then after the surge tank run a efi pump (but not a 044 as this will drain the surge tank to quickly)

So the question is then, what efi pump do people recommend?

Cheers

d_generate · Post by **d_generate** » Thu May 10, 2012 3:28 pm

I wouldn't risk a carby pump myself, if it's an in tank pump I'd go for a walbro 342, if it's an in line pump I'd be using a walbro in line pump then again my Lib runs fine with just a 342 in the tank, Bosch are "possibly" better but noisy pigs of things.

RSR 555 · Post by **RSR 555** » Fri May 11, 2012 1:26 am

Supply the surge tank with the carby pump then run the EFI pump off the surge tank and then have the return come back to the surge tank. The carby pump will supply enough. Best to make your surge tank with 2 top fittings (carby pump supply and EFI return line) and 1 bottom fitting for you supply to the EFI pump.

YouTube · Post by **El_Freddo** » Fri May 11, 2012 12:07 pm

RSR 555 wrote:Supply the surge tank with the carby pump then run the EFI pump off the surge tank and then have the return come back to the surge tank. The carby pump will supply enough. Best to make your surge tank with 2 top fittings (carby pump supply and EFI return line) and 1 bottom fitting for you supply to the EFI pump.

Don't you also need a third top fitting that's higher than the rest - this is for the return to the fuel tank - you don't want to be pressurising the surge tank, it will do funny things to how your engine operates!

Cheers

Bennie

RSR 555 · Post by **RSR 555** » Fri May 11, 2012 2:02 pm

El_Freddo wrote:Don't you also need a third top fitting that's higher than the rest - this is for the return to the fuel tank - you don't want to be pressurising the surge tank, it will do funny things to how your engine operates!

Cheers

Bennie

You can have a 4th outlet at the very top but all this will do is make the carby (facet) pump to run continuously. Without the 4th fitting you will have small pressure at idle but the facet pump will stop once this tank is full. The return fuel from the engine should be at low pressure due to the pressure regulator on the engines return fuel line and the EFI pump will be drawing from this at the same rate, plus the return fuel rate will be slightly less due to usage.