four stroke 60 hp high thrust.

[cowboycgt]

Hi, just recently purchased a centre console with a 60 hp yamaha four stroke high thrust. 2005
Seems the no.4 cylinder is not firing , runs sa little rough and when i remove the plug lead , no difference.
Has a good spark . Could it be fuel related?
any advice appreciated
thanks in advance

[99yam40]

If it has good compression and spark on all cylinders it more than likely is fuel related problem, but does not hurt to swap plugs to make sure that is not a problem

[cowboycgt]

Swapped top plug to bottom cylinder with no change.
Havent run the boat in the water yet{just got it yesterday}
wonder if it will change when engine wams up?
Could it be detrimental to the motor to run it like this??

[99yam40]

Did you do a leak down test on all cylinders before buying or at least a compression test to make sure cylinders are sealing properly?

running a motor to see if it will get better is never a good idea, find the problem and fix it