1986 20hp mercury carb rebuild

pmtrkr

Cadet
Joined
Nov 2, 2013
Messages
9
I have a 1986 20hp mercury outboard motor that runs only at half throttle. I replaced all the fitting from the fuel tank to the motor.Replaced the bulb in the fuel line checked and cleaned the fuel filter. I now get a good fuel flow to the carb. the motor now starts fairly easy, but only runs at half throttle. I am now going to get a carb kit. I am not much of a mechanic,is it a difficult to rebuild the carb or should I send to a repair shop?
 

carholme

Rear Admiral
Joined
Sep 4, 2010
Messages
4,845
Re: 1986 20hp mercury carb rebuild

Yes, you can do the job yourself if you have basic skills and tools. What is the s/n of your engine to verify the year.

To eliminate one problem before you order parts, run the engine again in the water and in gear and when you advance the throttle, have someone at the primer bulb and when the engine starts to bog, have them start pumping the bulb and see if it picks up rpms.

Gerry
 

pmtrkr

Cadet
Joined
Nov 2, 2013
Messages
9
Re: 1986 20hp mercury carb rebuild

the s/n OA929166 I believe it is a 1986 model.
 

pmtrkr

Cadet
Joined
Nov 2, 2013
Messages
9
Re: 1986 20hp mercury carb rebuild

What would be the problem if the primer bulb deal does make a difference?
 

carholme

Rear Admiral
Joined
Sep 4, 2010
Messages
4,845
Re: 1986 20hp mercury carb rebuild

That s/n comes up as:

MERCURY - ( 20 H.P. (1986 ))
Serial No: 0A929166 Model No: 1020226

Parts List for model 1020226:

18/20/25 H.P. (XD) - Mercury, Mercruiser, Force, etc. Parts Lookup

If pumping the bulb cause the engine to continue running and pick up speed, there is a problem with the fuel pump. It could be a defective diaphragm, check valve etc. What happens is that you become the fuel pump by your pumping actions.

The service manual you require is P/N: 90-43509--3

http://www.ebay.ca/itm/Mercury-Mari...anuals_Literature&hash=item25817e604a&vxp=mtr



Gerry
 
Last edited:

pmtrkr

Cadet
Joined
Nov 2, 2013
Messages
9
Re: 1986 20hp mercury carb rebuild

Also at looking at a manual for that motor it shows more than 1 carb for this motor. how do I determine the correct one that is on this motor?
 

carholme

Rear Admiral
Joined
Sep 4, 2010
Messages
4,845
Re: 1986 20hp mercury carb rebuild

Yours should be the one under CARBURETOR (MERC 20) (MARINER 20) which means that it is good for the Mervury 20 hp as well as the Mariner 20 hp.

Gerry
 
Top