fuel pump pressure
 

Do the mechanical stock pumps always pump same pressure, or does it increase with rpm?

How much pressure can a Q-jet take before it unseats?

Thanks


added:

Is it possible for a stock Merc high volume pump to put out 20psi at 2000rpm? Curious if a buddy was sold the wrong pump.

Pump Pressure
 

Stock pump about 5 to 6.5 lbs depending on the RPM . Anything over that your asking for problems. Damaged needle and seat bent float arms from fuel comming past the seat. If your going to run a high volume pump put in a fuel regulator and set it about 5 to 6 lbs.

The pump volume increases with rpm but the presure should not exceed 7 psi on a stock mechanical fuel pump. Sounds like the pump is wrong or defective.

Ok, thanks guys.

This is a buddies boat been working on last couple weekends. stock '88 454. Dumps fuel past N/S. tried new kit, float and carb body, no change, thus eliminated carb as the culprit. He just put a press gauge on it today.

I get 8psi at idle. 1050 Dominator, holley 120GPH six valve marine pump. High flow needle and seats, no problems.

However, you are working with a different animal. Sounds like he may be needing a pump.

I agree now that we know what the pressure actually is. I didn't think the mechanical pump was capable of that high of a pressure, so it never entered my mind as the problem.
A new pump is on it's way now.

US1 The slinkie joke is some Funny s##t thanks!

... :)

what kind of volume and or pressure will a factory mechanical pump from a 502mag off the water pump give???

will it support a 502 carb motor with a 800cfm holley without the electric pump that is high pressure for the efi

Some of the OEM Merc pumps are doing just that - too much pressure. We have warrantied a bunch.

Just got a call that the new pump fixed it. He must have had 1 of of the defective pumps. While comparing pump part numbers other day between different motors, the pump for the SBC's are having issues, and Sierra pumps are being sent in replacement. Possibly the manufacture defect also includes the pump for this '88 454?