1990 15 hp evinrude power fluctuates

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TC Scott

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got a '90 evinrude 15 hp, WOT used to go 17-21 mph now I go 10mph on average. Replaced all of ignition parts. Wasn't the problem. WOT will go for 2-3 mins at 10mph, then the rpm's drop for about 1 min, and then slowly climb back up. wondering if anybody had any input?
 
bktheking

bktheking

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Re: 1990 15 hp evinrude power fluctuates

Have you cleaned the carb at all? Could be a fuel delivery issue. What about compression, has it been checked as well?
 
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TC Scott

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Re: 1990 15 hp evinrude power fluctuates

haven't checked compression. it starts 2nd pull and idles and backtrolls fine, could it still be a compression issue?
 
bktheking

bktheking

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Re: 1990 15 hp evinrude power fluctuates

Anything is possible, just part of the ruling out possibilities. Your speed has more than half of what it used to get, not making power could be a compression problem, could also be a plugged up carb. Could be a reed issue, could be lots of things. Start with the easy stuff, screwing in a gauge and pulling the hope 5 times is easier than a carb overhaul and way easier than getting into the motor. Did you try pumping the bulb when it top's out to see if RPM increases?
 
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TC Scott

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Re: 1990 15 hp evinrude power fluctuates

haven't tried the bulb, but i will. Do you know the acceptable range i'm looking for with the compression?
 
bktheking

bktheking

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Re: 1990 15 hp evinrude power fluctuates

100+, more importantly is compression is close on both cylinders.
 
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TC Scott

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Re: 1990 15 hp evinrude power fluctuates

thanks, I appreaciate the info, i'll post the results.
 
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bob johnson

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Re: 1990 15 hp evinrude power fluctuates

TC Scott said:
got a '90 evinrude 15 hp, WOT used to go 17-21 mph now I go 10mph on average. Replaced all of ignition parts. Wasn't the problem. WOT will go for 2-3 mins at 10mph, then the rpm's drop for about 1 min, and then slowly climb back up. wondering if anybody had any input?
Click to expand...

are you sure the boat stil weighs what it used to??

lots of boat flotation foam soaks up water!!!!!!!! and over a really wet winter , your boat could weigh 300 lbs more than it used ...

thus killing boat speed..

I saw a guys 17" deep V Tracker boat that after he pulled the floor all his foam weighed about 500 lbs!!! ha ha

bob
 
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bob johnson

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Re: 1990 15 hp evinrude power fluctuates

endl3ss said:
Hey guys just wanted to make sure. The crossflow 175 is a 149 cu.in and the looper is a 160 cu.in correct?
Click to expand...

you are about 160 hp off course..............

not that a small hi-jack here and there isnt sooo bad!! ha ha ha

1990 175 hp, was 160.3 CU IN

before 1984 they were 149.4 cu in

bob
 
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