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-   Do It Yourself, Boating on a Budget (https://www.offshoreonly.com/forums/do-yourself-boating-budget-249/)
-   -   Fuel Pressure (https://www.offshoreonly.com/forums/do-yourself-boating-budget/198662-fuel-pressure.html)

badluck 11-15-2008 07:21 PM
I had the same issue with my Holley electrical pump, went back to stock mechanical. 7psi at wot.

blefever 04-28-2009 04:56 PM
Just wanted to let everyone know what i found to be my fuel pressure problem.

The pumps were tapped into the ignition wires from the key switch to the MSD box. I installed relays with a direct hot and ground to the battries and no more loss in pressure. The previous owner must not have been aware of the volt drop this caused to the pumps. I had to do a fair amount of digging to find this, but all is good now.

Thanks again to everyone who replyed with information.

blue thunder 04-29-2009 12:15 PM
Originally Posted by socalstone (Post 2738834)
I have similar fuel pressure readings on my carbed 454.
Can anyone describe how the low psi numbers translate to performance?

Does it just run out of power on the top end smoothly? or does it sputter, break up and run like crap?

Sorry for the sidetrack, but this seems related.
If you have a mech fuel pump you might consider going to a light weight pump pushrod. The stock rod is heavy and can cause the pump to float at high rpm.

Jb-fse 04-30-2009 06:50 PM
fuel pressure
 
BLEFEVER The fuel pump that you have was made by S-X PERFORMANCE for edelbrock.It is the same as a 18205.
This pump is rated for a engine that max h.p. is 480hp.
If you engine is less than that you probily have to small of a fuel pick up line. At 5lbs psi this pump delivers 1.16gpm at 6psi it is .83 gpm. at 3psi flow is 1.66 gpm. A 500hp engine requires only .70 gpm at wot. so when you pressure drops at throttle my best guess is that the pump is not getting fuel or you hve more hp than 480.

blefever 05-01-2009 12:10 AM
Fixed
 
Originally Posted by blefever (Post 2854622)
Just wanted to let everyone know what i found to be my fuel pressure problem.

The pumps were tapped into the ignition wires from the key switch to the MSD box. I installed relays with a direct hot and ground to the battries and no more loss in pressure. The previous owner must not have been aware of the volt drop this caused to the pumps. I had to do a fair amount of digging to find this, but all is good now.

Thanks again to everyone who replyed with information.
Jb-fse:

Heres what I found, see above. Motors are 375hp. All is good now. Thanks for the help.


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