I purchased a 25' Cal-2 with a 2000 8HP Johnson 2 cycle. I expected a fuel consumption of about 1 gph but am using about 2+ gph. Any suggestions, or were my expectations overly optimistic?
8 HP Outboard Fuel Consumption
- Thread starter txcalsailor
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that year could have a fuel enricher rather than a choke. If it leaks internally the motor will run very rich and use a lot of fuel. 2 gph sounds rather high. You may also want to throttle it back from full, it may be trying to push the boat faster than hull speed, which it wont be able to do.
I think your expectations are reasonable, but there are many factors to take into consideration.
a couple of the big considerations are,
what is the theoretical hull speed of your boat?
and at what rpm of your motor do you reach hull speed in calm water.
if you are trying to push the boat as fast and as hard as the motor will push it, you are probably pushing against "the wall".... burning gas and wearing out your engine without any measurable gain.
im sure if you locate the numbers stating the hull speed for your boat, you will find your 8hp 2-stroke will take it there at about 50% power..... and a big improvement in fuel economy....
also, has the motor ever had the propeller size changed from original?..... is the bottom of your boat clean?, are you trying to fight a current? or wind? using gas without ethanol in it (clear gas) will give a bit better economy than regular pump gas also....
a couple of the big considerations are,
what is the theoretical hull speed of your boat?
and at what rpm of your motor do you reach hull speed in calm water.
if you are trying to push the boat as fast and as hard as the motor will push it, you are probably pushing against "the wall".... burning gas and wearing out your engine without any measurable gain.
im sure if you locate the numbers stating the hull speed for your boat, you will find your 8hp 2-stroke will take it there at about 50% power..... and a big improvement in fuel economy....
also, has the motor ever had the propeller size changed from original?..... is the bottom of your boat clean?, are you trying to fight a current? or wind? using gas without ethanol in it (clear gas) will give a bit better economy than regular pump gas also....
Just as a comparrison, I know different boats and different engines, fresh water vs saltwater, but when we had our original Catalina-22,(swing keel), we had a 6 HP Johnson, (2-stroke, 2- cylinders). I ran some pretty extensive fuel useage tests because I was planning a trip up the Illinois River from Grafton to Chicago and needed to know how much fuel would be required. The C-22 being pushed at hull speed,(about 6 MPH), the 2-stroke Johnson burned 3/4 gallon per hour. My current C-22,(MK-II wing keel), with a 5 HP Honda,(4-stroke single cylinder), pushing my C-22 at 5.5 to 6 MPH and I get slightly over 20 MPG.
Don
Don
I once had an 8 hp 2-cycle Evinrude (basically same motor as Johnson) on a fin keeled boat that displaced 3200 lbs. Motor typically burned about 3/4 gph running at 3/4 throttle.
I second the prop possibility. Check with the manufacturer about what your RPMs should be at wide open throttle under load. If the revs are too high, you need more pitch in your prop. If too low, you need less pitch.
Way too much
Your fuel burn is way to much. I have a 1989 Evinrude 25hp on little skiff. 2 gph is about what it burns, running nearly wide open. I would strongly suspect the fuel enrichment device first. There is something pouring too much fuel into that motor. Or possibly some internal problem.
Your fuel burn is way to much. I have a 1989 Evinrude 25hp on little skiff. 2 gph is about what it burns, running nearly wide open. I would strongly suspect the fuel enrichment device first. There is something pouring too much fuel into that motor. Or possibly some internal problem.
I replaced the fuel pump on my 8HP Johnson Sailmaster. My fule consumption when thru the roof. After two trips, I happened to shut down in a quite bay and noticed this pretty rainbow running back across the water into the sunset. I was pumping as much out as I was in. A new clamp on the inlet and I was set.
Look for leaks.
Look for leaks.
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