Twin Volvo Penta 5.0GXI not even fuel usage.

[ahramyka]

I have 2002 Cruisers Yachts 2870 express with twin VP 5.0 GXi and DuoProp. Boat was purchased last year as project boat.
Both engines were rebuild, some other misc stuff fixed as well.. but mostly cosmetic things.
I added fox-marine gateway, stetted up NMEA network to have awesome numbers on one of plotters instead of old faria gauges.
After rebuild, both engines starts really nice, true turn key, but on GPH monitor show some things that not please me at all.
For example,
both engines are in sync, throttle is same for both.
2000 RPM -> Port engine has 4 GPH while Starboard 4.5 GHP.
2900 RPM -> Port engine has 6.9 GPH while Starboard 8.4 GHP.
3200 RPM -> Port engine has 8 GPH while Starboard 10 GHP.

Is such discrepancy ok? Or I must address fuel system pump/injectors?

 

[QBhoy]

Hi. I wouldn’t worry about it...because as far as I know, that gateway might only be as accurate as yours analogue gauges in terms of repeating RPM. I’m almost sure that is the case with this. As in it’s not taking the reading from the ecu and an exact reading. I think only gxi from a couple years later can do that. Might be corrected on this, but more sure I’m right than not.

 

[Scott Danforth]

because your starboard engine is working harder than your port engine

no you go old-school and pull the plugs and read them find out if the starboard is running rich or the port is running lean

this will also help you identify if the port engine is only running on 7 cylinders.

 

[ahramyka]

because your starboard engine is working harder than your port engine

no you go old-school and pull the plugs and read them find out if the starboard is running rich or the port is running lean

this will also help you identify if the port engine is only running on 7 cylinders.

thank you, for input, great idea check spark plugs.

 

[cptbill]

I doubt if you'll ever have them burning the same fuel, It would take a ton of money to have them built with the exact same tolerances and intake flow and everything else that's involved in fuel flow and then have the drives the exact same. If you don't find any thing wrong after your checks and it runs OK well then it is what it is

 

[ahramyka]

I doubt if you'll ever have them burning the same fuel, It would take a ton of money to have them built with the exact same tolerances and intake flow and everything else that's involved in fuel flow and then have the drives the exact same. If you don't find any thing wrong after your checks and it runs OK well then it is what it is

at this moment I think that's it's most reasonable approach.
My mechanic checked boat last week - annual service and checkup. and his statement same. everything sound mechanically.
And too many factors that may affect fuel usage, including props, boat layout.
starboard props has couple dings after log was chopped last year.
Boat layout is uneven,
Batteries, all seats and fuel tank aren't distributed equal. at least batteries and seats are on starboard side completely.
Fuel tank on 2/3 located ob starboard.
more weight on one boat side - boat drinks more.