1996 75HP Force fouling plugs

[dmessy]

I've recently rebuilt this motor and have good compression, no carbon build-up,and the timing is spot on. It accelerates cleanly and runs (loaded) at 4900-5100 RPM which is whats recommended. After a high speed run and return to idle,it stalls. It will start again only on high idle(not in gear)and runs poorly at 1000RPM for 15-30 sec. then revs up to 2300RPM like it should. After I get it cleaned out, it will idle roughly. As I suspected upon pulling the plugs, they were black,wet,and sooty. Can I(should I) rejet the single carb. slightly leaner to obtain the correct plug reading? I run factory specified Champions with a 50:1 ratio of 87octane "good" fuel and Stabil. The fuel filter and primer bulb are new also....

 

[my new fishmaster]

Re: 1996 75HP Force fouling plugs

I would check your fuel pump, I purchased a diaphram kit for my 75hp force but have not installed it yet. I wonder if there might be a recall on these engines, seems to me everyone has had similar problems!

 

[Fouled Plug]

Re: 1996 75HP Force fouling plugs

Did you rebuild the carbs at the same time? May just be an adjustment is needed to lean out the mixture a bit.

 

[dmessy]

Re: 1996 75HP Force fouling plugs

Fouled plug, No didn't touch the carb( only one with a 3 reed manifold). Going to go from a .094 to .092. main jet and do a plug read. No other adjustment to make other than idle mixture, pickup point(for timing only) and float level. All these are set per specs.<br />Just seems to be running rich so I'll let ya'll know the outcome.<br />New Fisherman, no recall I know of but these motors (and old Chryslers) are known for this. It's either full tilt boogie or off. I'll tune until I get a happy compromise...

 

[jimdi]

Re: 1996 75HP Force fouling plugs

I can pretty much guarantee you that it is one of two things - the idle is set too low - it should be about 900 rpm in GEAR!<br /><br />2nd the mixture is all wrong. set both at 1 turn out from seated to start. then adjust one in to find lean roll off - make a note - then find rich roll off - make a note. Correct adjustment is dead center of the two.<br /><br />do the same for the second carb. The correct setting for both carbs is the average number of turns out from seated of both carbs.<br /><br />ie:<br />#1= .75<br />#2 = 1<br /><br />both should be set at the average = or 7/8 of a turn out.<br /><br />jim