Fuel pump conversion, FI to carb

914GT · 02-17-2004, 07:52 PM

While waiting for some clutch/transaxle parts I ordered (PP of course) I'm working on the fuel system for my V8 conversion. For those daring enough to try this, I've found it's pretty easy to convert a stock FI fuel pump to work on a carburetor. I'd be interested if anyone has tried this before, as I didn't see anything come up in a quick search on the forums.

First of all, I bought a $20 pressure regulator just to see what happens on a stock pump. This doesn't work. The regulator isn't made to handle the high input pressure, and it would 'latch up' blocking off the flow. So what I did is pry the relief valve cap off the pump and remove the larger of the two springs. This lowers the pressure out of the pump to a little less than 20 psi. Still too high to my liking, I clipped a couple turns off the remaining spring. Now I got it down to about 10 psi which is just about right for a regulator. So with the adjustable regulator in series I can dial up any pressure from about 2 psi to 6 psi. I measured the flow rate and it moves about 15 gal/hr so that should be plenty. I re-crimped the relief valve cap back on, and put some epoxy around it just for added insurance against a leak. With a new filter, clamps, and hose I should be in business for around 25 bucks.

Anyone have any comments why this won't work?

Amark · 02-17-2004, 08:23 PM

Hi Guy,

The factory 6 carburetor pump looks identical to the FI pump. The difference is internal. My car is running one of these CB Performance pumps. Nice & quiet like the factory pump.

914GT · 02-18-2004, 11:58 AM

Mark, thanks for the tip. Might come in handy in case my old pump craps out. I have fun 'hacking' stuff, and if I can make a perfectly functional pump do what I need then I've learned something and saved a few bucks too (believe me, with the $$ I'm spending on this old car I try to save wherever I can). In this case I've found there's nothing exotic about these pumps and the only real difference between FI and carb types is in the pressure regulation. I bet the 'rotary' pump is quieter (looks identical to the in-tank unit in my old Acura Legend - very quiet). I'm mounting my 914 pump on two isolation bushings, not that I'll hear it above the sound of a 350 V8 with headers.