1985 50 hp Merc question

K

krawczmwk

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First, I am somewhat of a newbie to outboard maintenance. My motor has no power under load in WOT, in neutral, runs fine. My question may be simple, but I hope someone with more expertise can help. If the motor is running fine in neutral, could it be a stator problem? I have changed the plugs, but wanted to input before I dig deeper.

I have rebuilt the carbs and fuel pump BUT did not check sync and timing. I am going to replace fuel line and bulb and decarb the motor and then get it linked and synced.

I am not sure if is a fuel problem or a ignition problem.

Thanks for any help.
 
jerryjerry05

jerryjerry05

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Re: 1985 50 hp Merc question

Serial# model# 3or4 cylinder?Do a compression test,then a spark test..J
 
K

krawczmwk

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Re: 1985 50 hp Merc question

the serial number is 6485908, not sure of the model but it is an 1985. It is a 4cylinder. I plan on working on it this weekend. Can you let me know what type of gauge I need to do the compression test and where I might find one. I've purchased parts on iboats so I assume I can find one on the site.

thanks
mark
 
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krawczmwk

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Re: 1985 50 hp Merc question

Hey JerryJerry,

I bought a compression tester today. My question, I have read many posts on how to do a compression check and there seem to be many different ways to do one. I will list the steps I am going to take and if you wouldn't mind, check to see if I missed a step.

1. Warm engine
2. pull all of the wires from the 4 plugs
3. attach the guage to the first plug
4. ground the other 3 plug wires
5. in neutral, put throttle in wot
6. try to start the motor for 3 seconds, record the pressure
7. run the same test on the other 3 cylinders and record the pressure
8. check for pressure to be at least 100 and consistent across the 4 cylinders.

Does this sound right?

thanks
mark
 
K

krawczmwk

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Re: 1985 50 hp Merc question

Thanks, I will definitely check the exhaust.
 
C

CharlieB

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Re: 1985 50 hp Merc question

krawczmwk said:
My motor has no power under load in WOT, in neutral, runs fine....... I have changed the plugs..................
I have rebuilt the carbs and fuel pump BUT did not check sync and timing. I am going to replace fuel line and bulb and decarb the motor and then get it linked and synced. ...........
Click to expand...

Questions;
Did it have this problem before you rebuilt the carbs?
Did you check for a hot blue 7/16" spark on all cyl's?

No spark on one cyl may seem to idle fine yet be an absolute dog once shifted into gear.

Often after rebuilding carbs a novice will adjust the idle mixture to best idle, which is too lean for an outboard, they need almost another 1/8 turn out on the idle mixture screws.

Either, or both of these can make a substantial difference once in the water.

Test spark and compression and repost your findings.
 
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carholme

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Re: 1985 50 hp Merc question

krawczmwk;

In post #3, you said you weren't sure about the model number. It comes up as Model # 1050524:

Model Manufacturer Year HP
1050524 MERCURY 1984 50

marinepartsexpress show the s/n as a Canadian made engine.

Don't know if you have the parts listing:

http://www.crowleymarine.com/mercury-outboard/275.cfm

Gerry
 
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krawczmwk

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Re: 1985 50 hp Merc question

One other question, Do you think a decarb using seafoam might help the exhaust problem?
 
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krawczmwk

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Re: 1985 50 hp Merc question

Yes sir, I did have the problem and thought the rebuild might help. I will definitely check the spark. I am also planning to check the idle mixtrue. After reading all the posts in the forum, I'm pretty sure they need to be readjusted.

Thanks for your help.
 
K

krawczmwk

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Re: 1985 50 hp Merc question

Thanks Gerry. I will make sure I keep the info and the link.
mark
 
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wimico

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Re: 1985 50 hp Merc question

I tried the decarb with Seafoam first and the thing smoked like a tar kettle so I'm sure it might have helped the combustion chambers but it didn't even phase the exhaust tube. I had to actually chisel out that stuff it was so hard.
 
K

krawczmwk

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Re: 1985 50 hp Merc question

Wimico,
I read your earlier post. Thanks for the link and infor. Since I'm somewhat of novice, is it a big (complicate job for backyard mechanic) to do what you did with the exhaust. I guess my question is, is there a way to check the exhaust without disassembling the whole motor? I have the mercury manual and will check.

thanks
mark
 
R

RickyRegs

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Re: 1985 50 hp Merc question

carholme said:
krawczmwk;

In post #3, you said you weren't sure about the model number. It comes up as Model # 1050524:

Model Manufacturer Year HP
1050524 MERCURY 1984 50

marinepartsexpress show the s/n as a Canadian made engine.

Don't know if you have the parts listing:

http://www.crowleymarine.com/mercury-outboard/275.cfm

Gerry
Click to expand...

Sorry to just jump in here - but i have a 50hp mercury and i am trying to find the model year. I was told it was an '84 (with low confidence). My serial code is A103121 from what i can tell, it is an '85. Can anyone tell me?
 
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