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Joe, Marine Mechanic
Category: Boat
Satisfied Customers: 7251
Experience:  ASE, electronics, Marine mechanical and electronics, pwc, wiring, all around repair tech,
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I have a duel volvo penta 5.7 motors in a 2003 Doral but one

Customer Question

I have a duel volvo penta 5.7 motors in a 2003 Doral but one of the motors is reading a 70psi on the fuel pressure gage and the other is at 40psi so, whats the best way to tell whether it's the low pressure regulator or the high pressure regulator. Note i just changed the Gimble Bearing on this motor and fuel filters also?
Submitted: 2 years ago.
Category: Boat
Customer: replied 2 years ago.
Also I wanted to mention that it has good vacuum on the line. So the Boat will start to run good then just drops speed and if i leave the throttle in the same position it jumps up and down on the tachometer, and the motor then feels bumby and has backfired. I was told by a mechanic that I could run it and when it drops power to shut it down and look at the fuel level in the fuel filter and if its not full that the problem would be in the low pressure regulator, but if it's full of fuel it's probably the high pressure? Please help!!! Thanks
Expert:  Joe replied 2 years ago.
Thank you for allowing me to assist you, my name is ***** ***** I will be happy to assist you with your concern today.
The best way to test an regulator is to block it's return path, another wards you are preventing fuel after it from leaving and thus if the regulator is the issue the pressure will increase to normal range (this is done without engine running key on engine off). You should also explore the fact that the fuel pump itself might be on it's way out, I have had plenty not be able to test correctly until under way and checking with a fuel pressure gauge to isolate the problem. Lack of fuel in the filter and or lack f flow can also as stated be directly related to the pump.
Thank you!
- Joe
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