Priming fuel pumps...

[Belly_up]

Hey all,

Just got my injectors cleaned and flow tested, and bought a pair of new fuel pumps.

The injector cleaning and flowtesting cost me under $8, which was the cost of new o-rings and seals. didn't get flow figures, but was told they all flowed equal.

So then for less than the price of a 044 pump (which was my original thought), i got a 910 pump AND a 507 in tank lift pump.

My question is, what is the correct procedure to prime the 910 pump, to ensure it doesn't get any air in it?

I was thinking of just running the 507 on it's own for bit (it's self priming) into the 910. would that be enough?

Cheers for any ideas

Belly_up

[Sydneykid]

Surge tank?

[Zensoku]

If you do have a surge tank, i would be running the intank lift pump on it's own for at least 30 seconds until that surge tank is full and overflowing back to your fuel tank for awhile to remove the air bubbles.

If you don't have a surge tank, then your intank lift pump will have already pressurised the fuel line up to the 910 bosch pump in a matter of a few seconds, in which case, the over pressure relief valve in your lift pump will be bypassing to protect from burning itself out (ie: it's sensing a "blockage" - the non operational 910)

[Belly_up]

no surge tank at the moment, although i'm starting to think i might grab one, as i doubt the baffling in an early 80's fuel tank is sufficient for what i have planned.

what i was worried about, is that when the lift pump pressurises the line leading to the main pump, there will be air in that line that will get forced into the 910, and may become trapped depending on the orientation of the pump. I may be worrying about nothing though...

[Zensoku]

If your early 80's fuel tank was rigged up originally for a carbie system, (is this for a conversion? or a skyline?) then i doubt that there would be any internal baffling at all. For around $100+, a surge tank is a good investment to remove any chance of fuel starvation and air bubbles from a pressurised EFI system when you go hard around corners, expecially on a low tank.

Lets face it, any fuel pump will be sucking in some air in it's first few seconds of life... it will be unavoidable. Just prime the whole system the best you can.

[Belly_up]

It's a conversion, but the old tank was EFI (mmmm BMW goodness : ). i think i'll go the surge tank anyway, as i'd like to do some track days eventually, and like you say, it's cheap insurance.