I currently have a 1986 20' overnighter with a 1998 mercury 150 two stroke which was remanufactured by almars outboards in delaware in 2007 when I purchased it. The outboard is great and I have no problems only that I feel it is underpowered for my boat which results in poor fuel mileage. For example I did 55 miles the other day and I used 40 gallons of fuel. I have an opportunity to get a 1999 fuel injected 225HP mercury two stroke. I believe my fuel mileage will increase immensely with a bigger outboard because i won't have to push as hard. My main concern is if there is a major weight disparity between the two motors. I can't seem to find anything online about the weights of these motors. Please help.
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Repowering my 1986 20' overnighter
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Curmudgeon
Well-Known Member
Your fuel mileage may not increase, but you'll be much happier with the new horsepower. Weight should not be a factor ... :wink:
gxsess
Active Member
called grady when i repowered mine they suggested staying around 500 lbs wound up with a 200 optimax from almars. gas mileage went through the roof
sfc2113
GreatGrady Captain
pass.... it can handle the 225 mercs weight provided your transom is in good cond and not wet. , but you will get worse fuel economy with the 225efi, my buddy has that model and it sucks gas even on low rpm running.
175-200 2s should be plenty of power to push that thing, I am getting 2.5mpg average running 3700 rpms @ 21 knots and depending on sea conditions. If I push it to 5k I am still near 2mpg. Or a dfi engine should help with better mpg
175-200 2s should be plenty of power to push that thing, I am getting 2.5mpg average running 3700 rpms @ 21 knots and depending on sea conditions. If I push it to 5k I am still near 2mpg. Or a dfi engine should help with better mpg
gw204
Well-Known Member
Something is wrong. I had the same motor on my '85 20' Fisherman and could get over 100 miles on 40 gallons. Check your setup, prop, engine tune, etc.
Thanks for all the input. I did have my outboard checked and it posted between 110 and 115psi per cylinder so I don't think the outboard is the problem. I called Merc and they said I am properly propped if I am getting the recommended RPM's out of the motore which is between 5400 and 5700 and when i push to full throttle I get around 5500 RPM out of it. When I called Grady today they said that with a 150 out of the factory the boat should do 40 mph. I am no were close to that. 30 on a good day with the tide. Now I am really confused. PS when I called merc to get the weight differential between the motors they said that the outboard I have is a "very thirsty motor". HMMMM!! WISH I COULD AFFORD A 4 STROKE.
Fish Tank
Well-Known Member
Is your boat bottom painted? Is the bottom smooth? Is there stuff growing on it?
When I got my '89 it had a 150 johnson on it and it was a very thirsty motot, but would do better than 30.
My current '05 225 Opti is great, but have the one you are looking at checked out before you buy it.
When I got my '89 it had a 150 johnson on it and it was a very thirsty motot, but would do better than 30.
My current '05 225 Opti is great, but have the one you are looking at checked out before you buy it.
Daman858
GreatGrady Captain
Also, do you have trim tabs? If you don't trim the boat after you get on plane, you will be pushing water and using a lot of fuel and your speed will be down. The 150 is not a rocket but you should be doing better than you are.