Merc 25XD no fuel in #2 cylinder? - The Hull Truth

jfish · 08-25-2009, 02:02 PM

Owed since new always been cold natured rough idle %%$#! Started missing on bottom cylinder at idle and low rpms. Pull wire to bottom cylinder rpms do not change on motor. Pull top wire engine stops cold. Checked fire, plugs and coils all check ok. Swapped them around and problem remains lower cylinder not combusting. Checked compression both cylinders 95-100.

Engine will run ok but rough in tank. After 5 minutes pull plugs, top plug clearly firing and hot, bottom plug clean as a pin and cool. Where in the motor does the fuel seperate and head into each cylinder? There is only one reed box and one set of reeds? Do the tranfers plates seperate the fuel to each? Something is preventing fuel from reaching the lower cylinder?

Help?

A1 Outboard · 08-26-2009, 07:43 AM

The problem may be the seal on the bottom of the crank. A good mercury tech should be able to check crankcase compression for you to pinpoint the problem.