I was wanting to put an elec. fuel pump in place of the mech. pump can this be done and if so what pump should i use.Also had a question about the cooling system i am converting a 502 mpi injection system to a 525 i have sea water cooling on the intake of the 502 mpi there is a fitting in front and a 90 deg. bend hose on it going to the top of the circulating pump on a 525 there is no threaded hole to put a fitting there should i drill and tap the intake or is there another way this could be done thanks for any help

There already is an electric pump that primes the system. The mechanical pump fixed early issues with vapor lock. It looks like an old automotive pump but is not and I think it is a good feature of the 525. IMO, leave it alone.

The only thing I was trying to do I avoid running a sea pump with the fuel pump I have a gen 6 502. Mag with no fuel pump boss. So I thought I could replace it with a electric pump to feed the other elec pump to avoid buying sea pumps with fuel pump bosses thanks

You can replace both fuel pumps with an Areomotive AN1000 and adjustable regulator, many have done it.

Still can't figure out what you are trying to do with the 525/502mpi hybrid, and I read it three times.

i did some work to the motors two years ago afr heads hyd roller cam and a few other things so i am trying to upgrade from my 502 mpi system to a 525 efi system to try to get a little more out of it so i hope anyway

I see.

So you are saying that the 502 has a small hose from the circulation pump to the intake but the 525efi does not correct?

My circ pumps have pipe plugs plugging that hole on my 575scis. If the 525efi is not plumbed for it I don't see why you would need it.

BTW are you using a the closed cooling system from the 525 or going sea water?

I am using sea water that was my concern with that hose there is room to drill and tap a hole but if I did not have to I was going to plug off the circulating pump fitting thanks

holley makes a marine elec fuel pump, you can plum after the fuel/water seperator as a lift pump. 6 lbs pressure hope this helps.

that is what i am looking to do but put the pump before the fuel and water seperator just don't want to put the wrong pump and starve the high preasure pump. i think i am just going to find two sea pumps with fuel pump bosses and do it the that way i have the mech pumps thanks for your help

Marine fuel pump 6-8pound of pressure should work,,all your doing is replacing mech pump with electric