Fuel issues and no power

[Obiwanjacobi]

Hello I am trying to figure out an issue with my 2007 5.7 Volvo penta osxi-g. I keep getting power issues where I can’t get on plane and it won’t really go over 3000rpm. I have replaced all the filters, checked the pickup tube screen. Replaced the fuel pump with an oem Volvo penta pump and has fresh fuel. I am only getting 35-40 psi at the fuel rail on the new oem pump. The old pump I was getting 70 at the rail but the issue was with the low pressure pump. I was only getting 4 psi on the low side. What else should I look at and what should the pressures be? I am getting conflicting info online on what the specs are for this motor.

 

[Golfman25]

A little history would help. Is the boat new to you? When was the last time it ran normally? Any other changes?

Assuming your bottom is clean.

Since you seemed to tackle all of the fuel stuff, maybe move to a compression test.

 

[Obiwanjacobi]

A little history would help. Is the boat new to you? When was the last time it ran normally? Any other changes?

Assuming your bottom is clean.

Since you seemed to tackle all of the fuel stuff, maybe move to a compression test.

The boat is new to me but It was running fine before. I had a bunch of little issues that have now been fixed. I originally replaced the fuel pump with a cheap Amazon one worked until it didn’t. I replaced it with a different aftermarket pump which worked fine but it was defective and the low pressure pump was only giving me 3 psi after an hour. I now have a oem pump but it’s still not running right. It’s definitely a fuel issue because when the previous pump I had in before the low side went out I was getting 60 psi at the rail and the boat ran perfect. For some reason I am only getting 35 at the rail now with the oem pump. I’m leaning towards a bad regulator but I’m not sure what the pressure is supposed to be to even go off of.

 

[alk]

I can’t help much with the Volvo, but my Mercruiser which used to be MPI, was close enough on the injection to stock GM, so I just used the specs from a gm motor of similar vintage. Not sure what Volvo was selling in 2007.

Did you try searching the Volvo penta website for documentation? https://www.volvopenta.com/en-us/your-engine/manuals-and-handbooks/

Or the seloc / clymer type books? Perhaps these will have the specs? My guess is that 35 is way too low, and you should be between 60 and 70 psi.

Volvo Penta Stern Drives 2003-2012: Gasoline Engines & Drive Systems (Seloc Marine Manuals): Seloc: 9780893300746: Amazon.com: Books

Volvo Penta Stern Drives 2003-2012: Gasoline Engines & Drive Systems (Seloc Marine Manuals) [Seloc] on Amazon.com. *FREE* shipping on qualifying offers. Volvo Penta Stern Drives 2003-2012: Gasoline Engines & Drive Systems (Seloc Marine Manuals)

www.amazon.com

 

[PascalG]

Some tanks have a check valve / anti syphon valve at the top of the pick up. They can stick and cause fuel starvation.

 

[boatbum]

It would be interesting to know what happens if you could tap into a portable tank but I guess there are return lines to deal with. But as a test would it be possible to feed the system via the portable and let the rest go back to the boat tank? Not sure about the flow rates at all.