Fuel pump pressure

[Gorilla0178]

Looking at 2 holly fuel pumps. One is 1.5 - 4 psi and the other is 3 - 7 psi, I think. Carburated 3.0 looper. Which would be best? Both self regulating, up to 300 hp motors. Would the 1.5 - 4 psi be enough without a regulator? Would the 7 psi need to be regulated? The 7 psi one flows a little more per hour.

[W2F a V-King]

Not an OMC guy, but compare flow rates at the same pressure, and voltage.
The 3-7 psi may flow the same amount @ the same pressure as the 1.5 to 4 psi pump. Unless they are rated at top psi pressure.

All this should be in the specifications.

I like the 3-7 pump. Then regulate it if you have to. jmo

[SS Minnow]

In the factory manual they call for not less than 3psi @ 800 rpm in gear.
And like W2F above mentioned, you want to check flow rate of pump, Gallons Per Hour.

[Jay Smith]

I use the Holley red pump with Holley blue pump regulator set at 3-4 lbs on carbs, works for me ...

Jay

[Gorilla0178]

Ok. I guess the question should be, will the 1.5 - 4 psi one work without a regulator? I know 7 psi is pushing it without regulating.

[Gorilla0178]

One was 25 gph other was 35 gph if that helps.

[Merc 2.5]

Ok. I guess the question should be, will the 1.5 - 4 psi one work without a regulator? I know 7 psi is pushing it without regulating.

1.5-4lbs shouldn't need regulated, then again merc says 5lbs pressure , on other hand omc uses quite bit more gas than merc also , in my experiences.

[Speed Jr.]

I would absolutely use a regulator. Will be a far more consistent pressure at the injectors or carbs. My 2 cents.

[Gorilla0178]

Im gonna, I have a regulator already...

[W2F a V-King]

Larger of the two listed pumps with a regulator set to specification... Done

[Glastron1987]

Besides eliminating the need for a bulb, does replacing the properly operating pulse fuel pump with and electric one provide any benifit in the way a carbed motor starts, idles, or runs?

[Gorilla0178]

I only replaced it on this motor because I made a fuel rail that has a larger inside diameter than the stock plastic fuel rail. Mine had the dual pump setup with the small fuel pumps. I went with a aircraft grade pump that is very nice and way quieter than the old holly style I had on my other boat. It is a Facet Gold-flo pump. I just feel better having a electric pump rather than the little fuel pumps.452879452880452881