I have an 87 mercury 20hp motor. Runs like its flooded the it will jump and run fine for a few mins then do it

Question

It will jump then run fine then back to bogging out. Any suggestions?

Answer 1

I have a v-8 I/O, and I had a similar problem: while cruising, all of sudden it would lose a lot of power and come off plane - then it would surge again back to normal.

Mine ended up being a cracked spark plug.  The white ceramic part had a thin crack, and it was probably shorting itself out intermittently to the engine block, and not firing.

So.......check spark plugs, make sure the fuel isn't spoiled, make sure there's no water in the tank!  thats a big one too, if water gets in there, it will run crappy.

Answer 2

Check your gas tank to see if there is debris being drawn  intermittantly to the pick up tube thereby cutting off the supply. Your motor may well be fine ! Good Luck

Answer 3

these symptoms point to the fuel system,maybe the float wants checking in the pump.