SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: Leo Arevalo on July 09, 2020, 05:09:34 PM

Title: Fuel pressure issues
Post by: Leo Arevalo on July 09, 2020, 05:09:34 PM
Hello everyone,  I just purchased my first jet boat. It's a 1971 omega 460 bbf. I'm having trouble  trying to figure out why I'm losing fuel pressure  when I hit the throttle.  At idle I have 5 psi and drops to zero when I accelerate. It's a 850 double  pump holley, with a holley electric  fuel pump.
Title: Re: Fuel pressure issues
Post by: angermgmt on July 09, 2020, 05:21:47 PM
Fuel float levels. Fuel needs to drip out when you check.


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Title: Re: Fuel pressure issues
Post by: TrollerDave on July 09, 2020, 05:56:39 PM
Welcome to SCJB and jet boats.

If it’s not the floats, maybe check your fuel stream to the carb. Which Holley pump do you have?  I know the blue has a cover on the bottom held on by 4 or 5 screws. You can take the cover off and see the pumping mechanism.  The canes can sometimes stick to the rotor. Or there is a screen that might be a little clogged. If you open it, be careful. The vanes could fall out and there is a rubber gasket you want to put back in the right direction.

How old are your fuel lines?


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Title: Re: Fuel pressure issues
Post by: Leo Arevalo on July 10, 2020, 12:00:23 PM
I have the red  holley fuel pump, and the fuel lines i dont know how old they are.
Title: Re: Fuel pressure issues
Post by: TrollerDave on July 10, 2020, 12:34:37 PM
I have the red  holley fuel pump, and the fuel lines i dont know how old they are.
I guess what I was getting at is, if it’s not your carb float level or needle and seat, it seems something is restricting flow to the carb. The red pump can be opened and checked like I described above.
If the fuel lines are old, they can collapse or suck air.
Does your boat have 2 gas tanks? If so, Is there a selector switch or can it draw from both tanks at the same time? If you have the selector switch, draw from each tank to see if it happens with both.
 Are you able to check while the boat is in the water or in the driveway on a hose? Jet pumps need water flowing through them to lubrications and cool the packing. Running it out of the water for too long isn’t good for the pump. Just an FYI.



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Title: Re: Fuel pressure issues
Post by: 96Laveycraft21Xt on July 13, 2020, 12:35:52 PM
I guess what I was getting at is, if it’s not your carb float level or needle and seat, it seems something is restricting flow to the carb. The red pump can be opened and checked like I described above.
If the fuel lines are old, they can collapse or suck air.
Does your boat have 2 gas tanks? If so, Is there a selector switch or can it draw from both tanks at the same time? If you have the selector switch, draw from each tank to see if it happens with both.
 Are you able to check while the boat is in the water or in the driveway on a hose? Jet pumps need water flowing through them to lubrications and cool the packing. Running it out of the water for too long isn’t good for the pump. Just an FYI.


This ^^^

need to take the time to very each individual area of the system.



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