1989 EVINRUDE 50HP 2 stroke top cylinder is 90psi and bottom is only 60.

mrkingnh

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Hello all, I have a 1989 EVINRUDE, 50HP, 2 stroke top cylinder is 90psi and bottom is only 60. Any ideas before I rip open the Head??
 

AEROCOOK

Master Chief Petty Officer
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Jul 28, 2004
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Re: 1989 EVINRUDE 50HP 2 stroke top cylinder is 90psi and bottom is only 60.

Do a decarb before you take a wrench to it.
 

mauryc

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May 2, 2005
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Re: 1989 EVINRUDE 50HP 2 stroke top cylinder is 90psi and bottom is only 60.

+1. Decarb with seafoam first and see if the compression gets better in #2.
 

boobie

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Re: 1989 EVINRUDE 50HP 2 stroke top cylinder is 90psi and bottom is only 60.

+ 2 on the decarb.
 

mrkingnh

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Re: 1989 EVINRUDE 50HP 2 stroke top cylinder is 90psi and bottom is only 60.


Thanks, when I bout this motor the lower unit was removed (still is). I had to disassemble the lower unit and I have major issues in that area. The forward gear set needs to be replaced...blah blah blah. lol Is it okay to just plug a secondary fuel source to the water separating fuel filter and try to run it? I am sure the VRP was been removed (there is no oil can in the boat). I have no clue how long it has been sitting? I did use sea foam poured directly into the spark plug hole on both cylinders last night (recommended by local mariner). The upper moved up about 2psi and the lower is now at 70-72 (from 60).

I will try to decarb this evening.

Thanks again... I'll reply with results.
 

mrkingnh

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Jun 10, 2013
Messages
31
Re: 1989 EVINRUDE 50HP 2 stroke top cylinder is 90psi and bottom is only 60.

I used a secondary gas source (premixed gas in a windshield washing fluid bottle), to start the motor today for the first time. It runs!! Actually sounds really good. Theres obviously something going on as I did another compression test after starting it a few times. The new test raised Cylinder # 10psi. Im now reading #1-90 #2-70. I only let it run for a few seconds as there was no water supply. Does anyone know what I could do to substitute the water pump? The DeCarb instructions you provided says to warm up the motor. I was thinking I could use an old fishpond pump or something to that effect??

Thanks
 

Watermann

Starmada Splash of the Year 2014
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Jan 12, 2013
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13,747
Re: 1989 EVINRUDE 50HP 2 stroke top cylinder is 90psi and bottom is only 60.

Is the lower unit on the motor? Not sure why you can't put it on muffs and use a garden hose.
 

mrkingnh

Seaman Apprentice
Joined
Jun 10, 2013
Messages
31
Re: 1989 EVINRUDE 50HP 2 stroke top cylinder is 90psi and bottom is only 60.

Is the lower unit on the motor? Not sure why you can't put it on muffs and use a garden hose.

Yes the lower unit is removed. I found the forward and pinion gears ate each other. Looks like the drive shaft backed off at some point and the gears munched themselves.
 

Watermann

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13,747
Re: 1989 EVINRUDE 50HP 2 stroke top cylinder is 90psi and bottom is only 60.

Stuff a hose in the water intake pipe and pour the water to it, should be fine to run it like that as long as water is getting to the powerhead. Or just wait until the lower is back on since it's not going anywhere anytime soon.
 
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