Fouled Plugs

[1979SeaRay]

I use my boat primarily for fishing and do a lot of trolling at low speeds, typically 1-2mph. I usually run NGK in my Mercruiser 898 Chevy 305 and recently changed the plugs to Champion RV8C which is all the Marina had in stock. I only ran the pulgs for two outings and during the first one the boat ran really nice. On the second outing after a troll I had bogging down problems and limped back to shore. After doing fuel pressure and vaccum tests I pulled the plugs and noticed they were all fouled up. Black soot-carbon buildup. I realize trolling for long periods of time will create carbon buildup but this seems a little excessive after only two outings.

Any thoughts on what is causing the plugs to foul up so quickly? I didnt think the Mercruiser engines were as succeptable to carbon buildup as much as an outboard, and I never had a problem this bad before I changed the plugs. Is it possible the Champion plug is not running hot enough? I do have an electronc ignition converted from points. I also had gas on the plugs when I pulled them.

 

[hullofalottatrouble]

Re: Fouled Plugs

http://www.4secondsflat.com/plug_chart.html - thought i would provide this link it think its helpful for reading your plugs..

did you gap the champion plugs before you put them in? I bought some NGKs recently and the gaps were all over the place..

did the NGKs never look fouled up before? ive heard people say champions are garbage.. you might want to switch back the NGKs

 

[1979SeaRay]

Re: Fouled Plugs

http://www.4secondsflat.com/plug_chart.html - thought i would provide this link it think its helpful for reading your plugs..

did you gap the champion plugs before you put them in? I bought some NGKs recently and the gaps were all over the place..

did the NGKs never look fouled up before? ive heard people say champions are garbage.. you might want to switch back the NGKs

I did not gap them, I didnt have a gapping tool and when I went to buy one from the marina the mechanic who sold me the plugs said you dont need one, they are already gapped properly. By the way the plugs definately look like #3 on the chart.

I also heard some GMs dont run well with Champion plugs.

 

[Robj]

Re: Fouled Plugs

I am surprised that Don has not chimed in. I think he might say something like get rid out of those Champion plugs. Try NGK, gap them correctly and then try. Haven't heard too many people saying how great Champion plugs are, most posts are to the contrary.

Good luck,

Rob.

 

[1979SeaRay]

Re: Fouled Plugs

wondering if I should spray some Seafoam down the carbs to de carbon the engine before installing new plugs?
I would like to try and figure out what is causing the problem rather than chase it with new parts.
Don S?

 

[ziggy]

Re: Fouled Plugs

i think i'd just switch back to ngks and see what happens since ya had no issues prior to the champions......
gap them. my dealer claimed that same bs about not needin to gap my new plugs. (ngks) they may have been gapped, but not for my engine....gap em......

 

[Don S]

Re: Fouled Plugs

I would like to try and figure out what is causing the problem rather than chase it with new parts.

Let's see, you normally use NGK, and never have problems, suddenly you change to Champion plugs and you have problems. You don't gap them because some counter salesman (Probably not a mechanic) said it's not necessary. Let me guess here, but you didn't find any info about it in your Clymers manual either.

My advise....... Follow ziggy's advise.

 

[1979SeaRay]

Re: Fouled Plugs

Let's see, you normally use NGK, and never have problems, suddenly you change to Champion plugs and you have problems. You don't gap them because some counter salesman (Probably not a mechanic) said it's not necessary. Let me guess here, but you didn't find any info about it in your Clymers manual either.

My advise....... Follow ziggy's advise.

I know people like me who dont know what they are doing probably annoy guys like Don S. but I appreciate the advice. By the way I scoured ebay for a genuine Mercruiser manual, not Clymers!

 

[KaGee]

Re: Fouled Plugs

I also heard some GMs dont run well with Champion plugs.

GM's run best on the AC spark plugs that came with them.