4 HP Mercury 2 Stroke, 1992, Carburetor Issue.

[Greg_E]

i just picked up a Mercury 4HP 2 stroke.

I read the sticky to identify the engine using the serial number. Using one of the links in that thread, I identified it as being a 1992. SN A907213.

The engine is in very good condition for its year, but when I tried to prime it, gas was dripping from the carburetor at the base gasket. I notice that one of the nuts that secures the carburetors was missing, so assume someone has made an unsuccessful attempt to fix it.

I do have the manual for the engine.

I did not find any aftermarket carb rebuild kits for this motor. Does anyone make one or is it a dealer only item?

Are there any common problems with theses carbs that I should look at first?

Also, I noticed that the recommended spark plug is not what was in the engine. The recommended plug is a NGK BP7HS-10 or BPRHS7-10. It had a Champion Y78C plug which is center fire plug ( not sure that's the correct term). In any case it is a fixed gap plug. Is that an alternate for the factory recommended plug?

Thanks for your replies.

 

[Bosunsmate]

Re: 4 HP Mercury 2 Stroke, 1992, Carburetor Issue.

try searching for this part # and see if it fits with your model
855546A 1
Is that the 2cyl or 1cyl?

 

[Greg_E]

Re: 4 HP Mercury 2 Stroke, 1992, Carburetor Issue.

Thanks for the reply.
I have since discovered that the engine is not a 1992. The site I initially used to identify the year incorrectly identified it as a 1992.

I think now that it is a 1986. I still have been unable to positively identify that serial number as a 1986, just that the serial number is higher than the beginning serial number for 1986 motors. When I search my serial number, it comes back serial number not found.

The carburetor is stamped WMD 7/85. I assume WMD stands for Walbro Marine division and 7/85 was the date of manufacture. They also used Tillitson carbs on that year. From the diagrams, they look very similar.

It is a one cylinder motor.

 

[carholme]

Re: 4 HP Mercury 2 Stroke, 1992, Carburetor Issue.

That s/n comes up as:

MERCURY - ( 4 H.P. (1986 ))
Serial No: 0A907213 Model No: 1004206

Parts Listing for model 1004206:

4 H.P./4.5 H.P. - Mercury, Mercruiser, Force, etc. Parts Lookup

See sparkplugs under FLYWHEEL AND IGNITION COMPONENTS

Carb kits:

MERCURY OUTBOARD CARB KITS 18 THRU 35 HP -- MASTERTECH MARINE

Gerry

 

[Greg_E]

Re: 4 HP Mercury 2 Stroke, 1992, Carburetor Issue.

Thanks carholme. This is the first Mercury I've worked on so I'm still finding my way around. Have always worked on J/E motors prior to this one.
The carb has gas pouring out when I prime the bulb, but it fired up briefly on the second pull. I think once the carb is squared away, it will be a nice running engine. Someone was in the carb before me and didn't put it back together correctly.