2002 8.1L fuel consumption

Marcus E

New Member
Dec 14, 2010
97
Chesapeake Bay
Boat Info
340 Sundancer
Engines
8.1 Mercruisers
It seems as though I'm burning a lot of fuel....much more than 30 GPH. What steps can I take to improve GPH?
 
Some more detail might be helpful. What kind of RPM and speed are you talking about? Also, is this combined or per engine? The 8.1 engines are great engines and perfect for the 340DA but not all that fuel efficient.

FYI- Last weekend, I was out with my friend on his 340DA with T-8.1 and he opened it up. He was at WOT, (don't recall exact RPM) and we were running abt 39-40mph GPS speed and according to Smartcraft, burning around 64-65GPH. Of course that was at WOT and this was with camper canvas up. His engines have relatively low hours and in excellent condition.
 
Combined. Usually run at 3300 RPM's. Boats on plain and trimmed out. Someone told me I need to run at a higher RPM....another said to tune the props. Not sure what to tweak.
 
Lots of post on fuel burn rates. Wide open I burn 50 GPH. At 3200 RPM just before 4 barrels open think it is 20GPH.
 
As northern said, there are a lot of threads on fuel burn particularly for the 340 as well. Not sure about RPMs but I believe the best mpg for cruise reported by owners of 340DA w/8.1 engines is .8MPG. Although fuel burn on Smartcraft is not 100% accurate, you can use it to find the best spot for you. Depending on your speed, I would guess 30GPH combined would be not far off from average consumption at cruise speed. I am sure others will chime in though.
 
I think this is posted on the wrong thread since we do air conditioning and refrigeration, but I can look into it.
 

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