200 merc plug fouling
G'day brains trust, I have a 2005 200 saltwater merc 2 stroke. 270hrs ive done 100hrs drama free over the last few years. I've recently inherited a drama where it is fouling one plug. I've swapped coils problem didn't move I've just got injectors serviced. No smoking gun in the report. All holes have exact even compression of 87psi. Rest of the plugs look like a well running 2stroke, little oily but clean. The motor runs fine, but the last time it's fouled it was after a run of 15mile at 3800 didn't miss a beat. Got to hillarys dropped down to 5knts and it was fine till we got to the ramp where it noticeably fouled the plug just before the ramp. New fuel filters and new set of plugs. Main question is has anyone had this issue what was the fix? It's fouled the one plug twice in the last 3 trips. Strangely enough I ran a tank of 95 and some fuel stabiliser/cleaner in the second run with brand new plugs and when I pulled them all plugs were mint motor was a tad smokier than usual and thirstier tho. Motor starts and idles mint, nothing suggests an issue other than one plug fouling. Top port side.
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Gunnawundai
Posts: 48
Date Joined: 04/04/18
Rings are shot. You should
Rings are shot. You should have over 100psi in all pots.
Sorry for the bad news!
Rob H
Posts: 5800
Date Joined: 18/01/12
Did you check the
Did you check the compressions yourself or someone else?
While 87 is on the low side it doesnt warrant a full rebuild if it runs fine and given all the compressions are even (supposedly) so its not the source of the plug fouling.
As a mechanic myself though I'd be sus that all are "exactly 87 psi", and I'd question whether they'd actually checked all cylinders and that the compression gauge is ok.
Then swap the injectors between cylinders.
The next step would be to put a little oil down each pot and check again maybe, if the variation isnt similar across all cylinders it may point to the issue
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rob90
Posts: 1526
Date Joined: 06/02/13
I done the test myself on a
I done the test myself on a cold motor with closed throttle so maybe i done the test wrong. I ended up pulling and getting injectors serviced and now run bp and it's running fine after 3 trips. After seeing a technician pouring a 20l mystery drum down the tanks at 7 eleven I'm a little sceptical on their fuel quality. Will pull plugs before next trip and see if all plugs are even. The motor gets up and boogies so I'd say she is running fine. 21ft fibreglass boat 32knts through slop is good enough compression for me. Cheers for the reply
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rob90
Posts: 1526
Date Joined: 06/02/13
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Hi my name is rob............. and I'm a........... fishaholic