LP pump for HP feed?

datsun510 · Post by **datsun510** » Tue Jun 06, 2006 12:04 pm

Hi, I'm having some fuel delivery problems with my EFI setup.
Basically, my high pressure pump (msd 2225) sounds like it's cavitating. It is mounted below the tank, with 3/8's lines, but the only thing is that the rubber hose has to go vertical maybe a foot or so. Would this cause the pump not to suck enough?

My question - Is it possible to hook up a low pressure pump IN LINE with the feed for the high pressure pump? It would look like this :

Code: Select all

Tank------LP-----HP-------injectors----.....

Thanks, Matt.

renns · Post by **renns** » Wed Jun 07, 2006 8:49 am

Matt,

So long as the LP pump has a flow rating greater than the HP pump, you should be fine. If not, then you may just make matters worse.

Roger.

PSIG · Post by **PSIG** » Wed Jun 07, 2006 9:10 am

Matt,
Verify you don't have some other problem such as sucking air or a pickup line sucking bubbles at a joint, clogged screen, internally collapsed or shaved hose, etc. MSD pumps can generally pull several feet vertical (not recommended) and should not be a problem if it's mounted under the tank - even if it has to go vertical (up) first - as it then works as a siphon.
Does your system have a standard return line?
Have you tested the system to see if youre getting something close to the rated flow?
David