Fuel pump Maybe?

[Peter P @ Racoon Lake]

1986 Mercury 25hp serial #A912038 electric start on pontoon. Went for midnight ride and motor started and ran great. Docked it about an hour later. Next morning motor turns over but will not start. I can hear the choke engage when I push the key in. I put a little gas directly in each cylinder and it fired for a second so I know it is getting spark. Sounds like fuel pump maybe? I'm new to this so some suggestions would be appreciated greatly. Will fuel pump go bad that fast? Is it a difficult repair or rebuild or should I hire a pro? I was thinking of replacing entire unit but couldn't find one. Could it be something other than fuel pump? Thanks in advance. Happy boating.

 

[ondarvr]

Try squeezing the primer bulb, this will fill the carbs and act as the fuel pump. Normally it's something other than the fuel pump, but being that old it could be.

 

[Peter P @ Racoon Lake]

Tried the bulb squeezing.. Still wouldn't start. Suggestions please. I need to be on the water!

 

[ondarvr]

If the bulb got hard, and it still wouldn't fire, then it's not the fuel pump stopping fuel from entering the motor.

​Take the drain plug out of the carb(s) and squeeze the bulb to ensure fuel is flowing, this may also purge any water from the float bowl.

 

[roscoe]

1986 Mercury 25hp serial #A912038 electric start on pontoon. Went for midnight ride and motor started and ran great. Docked it about an hour later. Next morning motor turns over but will not start. I can hear the choke engage when I push the key in. I put a little gas directly in each cylinder and it fired for a second so I know it is getting spark. Sounds like fuel pump maybe? I'm new to this so some suggestions would be appreciated greatly. Will fuel pump go bad that fast? Is it a difficult repair or rebuild or should I hire a pro? I was thinking of replacing entire unit but couldn't find one. Could it be something other than fuel pump? Thanks in advance. Happy boating.

Will the fuel pump go bad how fast ?

Yes the diaphragms wear out, they need to be rebuilt every 8-10 years especially if ethanol gas was used.

You really don't know if you have spark on BOTH plugs, may only be on one. Need to do a proper spark test.

 

[Peter P @ Racoon Lake]

The bulb does not get hard after squeezing......

 

[ondarvr]

The bulb does not get hard after squeezing......

​Then you may have a leak or the float needles aren't seating correctly. The fuel pump can leak into the motor too, this can keep it from starting. But since it fires when you put gas in it, it means it's not flooding.

​Is the arrow on the primer bulb pointing up when you squeeze it, and is there enough fuel in the tank? If the pick up tube is plugged, or has a hole in it, it may not prime when you squeeze the bulb.

 

[Peter P @ Racoon Lake]

The arrow on the bulb is pointing up and it does fill the bowl. I can keep pumping but the bulb does not get hard. Fuel tank is 3/4 full. I think i may need to do spark test on both plugs. I did use 89 octane gas the last two times I filled up instead of regular 87 octane. Surely that shouldn't matter?

 

[Peter P @ Racoon Lake]

Reed valve possibly?

 

[Peter P @ Racoon Lake]

Cleaned carb, replaced bulb and valve at the fuel tank and now runs great.