Fuel pressure

[ericcarr]

When adjusting fuel pressure to the carburetor, do you go by the number when the Motor is running, or after you shut it off in the number that it is at at that point because while my motor is running I am getting 8 1/2 to 9 pounds of pressure, as soon as I turn it off the needle goes to you about 5 pounds

 

[Eric 3.7LX Alpha 1]

Engine running, for a carb, that's a little too high. I'd be trying for 4-5 psi.

 

[dubs283]

Iirc mercs standard mechanical fuel pressure for carbureted engines is 3-7 psi steady pressure under load.

If you're too high you run the risk of overpowering the needle/seat causing flooding issues. Correction for too much pressure is to add a thicker gasket between the pump and block

 

[achris]

When adjusting fuel pressure to the carburetor, do you go by the number when the Motor is running, or after you shut it off in the number that it is at at that point because while my motor is running I am getting 8 1/2 to 9 pounds of pressure, as soon as I turn it off the needle goes to you about 5 pounds

As far as I recall, the Briggs & Stratton relies on gravity feed, there is no pump....

(That's a hint, tell us WHAT ENGINE! Then we can look up the appropriate service manual and give you the factory spec, instead of just guessing..)

Chris.......

 

[ericcarr]

Oh duhhh, sorry forgot that part…it’s in my 1990 sea ray sundancer with the 7.4 merc motor with bravo 3 drive.

 

[achris]

Oh duhhh, sorry forgot that part…it’s in my 1990 sea ray sundancer with the 7.4 merc motor with bravo 3 drive.

That will be manual #15...
Here you go...

 

[Scott06]

He forgot to include he is running a Holley DP, while these factory settings are likely ok Eric u may want to consult with Holley as to the fuel Pressure the carb is intended to work with

 

[ericcarr]

He forgot to include he is running a Holley DP, while these factory settings are likely ok Eric u may want to consult with Holley as to the fuel Pressure the carb is intended to work with

Yeah I’ve sent them messages and emails. No response so….

 

[Scott06]

Yeah I’ve sent them messages and emails. No response so….

Try using google a little https://documents.holley.com/199r7923-2rev2.pdf

page 5 has fuel pressure.

Also has other basic tuning parameters