Spark Plug Engine trouble

[wilson973]

I have been working on my boat for over a week now. It has been jerking at half throttle and above. I have done everything. Today I just started pulling plug wires off as it was running. Pulled the wire off the top one, engine died. Replaced wire started back up then pulled wire off the second one. Engine died. Replaced wire and started up pulled wire on third one. Engine didn't change a sound. I have a good spark on the plug and it is getting good gas. Can anyone help me with any ideas??????????? Please Im at wits end.

 

[ftl900]

Re: Spark Plug Engine trouble

If there is no change when #3 is unplugged, that indicates that #3 is not contributing to making power, whether it's a fuel issue, a hole in the piston, or other problems.

If you're sure #3 is making good spark, I'd pull the plug and see if it's wet or smells like fuel. Then maybe check the compression for that cylinder.

 

[wilson973]

Re: Spark Plug Engine trouble

The plug is wet with fuel and the compression on that cylinder is 112 lbs.

 

[surrender]

Re: Spark Plug Engine trouble

Have you checked to see if your getting spark on number 3? I would guess not if you have fuel and compression. Swap a the coil with one of the known good ones and try again. If number 3 works now you have a bad coil.

 

[Vic.S]

Re: Spark Plug Engine trouble

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