Hotter plugs??

[Searenity]

my 1986 black max 150 fouls plugs consistantly. Some one at the marina suggested going to the next hotter plug. Any thoughts on this??? I am using BU8H ngk plugs now, thats what the manual calls for. Any other thoughts would be entertained as well. Thanks

 

[sloopy]

Re: Hotter plugs??

you can use hotter plugs, but you risk alot, first I would make shure you are using the right gap and that you have CHAMPIAN plugs (just bring you current plugs to a dealer and ask them for the champian equivelent)

 

[Reel Appeal]

Re: Hotter plugs??

I think those are non-ajustable surface gap plugs you have there.Make sure mixture is not too rich first.Then I might suspect a weak ignition such as coils??<br />Are your thermostats IN and working properly?Motor may be running too cool.<br />I have a '86 Merc 175 with the oil injection removed.I have found the gas/oil ratio should be right on the money 50:1 in order to run well.You should also be using 89 octane or higher gas in that motor...

 

[Dhadley]

Re: Hotter plugs??

Reel - why does that motor require higher octane fuel?<br /><br />Just curious!

 

[BillP]

Re: Hotter plugs??

I'm not a merc guy but did have a merc years ago that was very sensitive to what oil I used. Anything other than merc oil made it hard to start and foul plugs. <br /><br />I would check these first...<br />compression test<br />up one plug heat range and check plugs often<br />thermostat<br />oil ratio and type (synthetic may help)<br />timing<br />elec system (stator?)<br /><br />Doesn't that engine have fixed jets (non adjustable)?

 

[RICKRICK1]

Re: Hotter plugs??

Before going to hotter plugs have you checked to see exactly how much oil you are using per gallons of gas. Several friends had the same problem and found out the oil injection system was mixing at 26 to 28 to 1 ratio. removed oil injection system and started using premix and they havent had problems yet. The best way to check this is to fill the oil tank and gas tank run and measure amount of oil verses gas when you refill.

 

[Greg Lawrence]

Re: Hotter plugs??

well i think my problem was my thermostat on my plug fouling issues. i think it was stuck open and not seating all the way.. my motor ran too cool, when i replaced it, bam it didnt foul plugs and it burnt way cleaner. i think it runs harder now.

 

[Reel Appeal]

Re: Hotter plugs??

Hello again,<br /> <br /> All Mercury V-6 motors require gasoline with a minimum posted pump octane of 89(research octane #94)Higher horsepower motors require higher octane/lower octane fuels can cause ring sticking/port plugging in 2 cycle's.I have a Clymer/Mercury shop manual covering that motor...<br /><br />FROM CLYMER MANUAL:IDLE/ACCELELORATION PROBLEMS RESULTING IN SPARK PLUG FOULING(V6 Engines)<br />Check carbs for gray gaskets(motor ser.#below A157595)Replace with black if present.(contamination)<br />Check and reset carb. floats<br />Check throttle shutters(behind choke flap)<br />Check and adjust timing and syncro.(idle speed set to 600-700 rpm in FORWARD gear in the WATER)<br />Install NGK BU10H spark plugs...(in manual )

 

[Dhadley]

Re: Hotter plugs??

Very interesting. Everything I have from Merc says to use 87 octane on recreational motors including the 250. The consumer performance and race motors are different naturally.<br /><br />???

 

[Reel Appeal]

Re: Hotter plugs??

Hi Dhadley,<br /> My Clymer manual covers 1972-1989 models.I have a theory that maybe the 1980's Merc's have a higher compression which would require the use of higher octane??Might be the newer Merc's don't require 89 octane?What do you think?