Black Spark Plugs

[Craig-]

Re: Black Spark Plugs

I pulled this one out of my 90hp Ocean Pro oil injected carburetor motor today to show you. All 4 plugs look the same. Plugs were new this season and have around 120 hours on them and anti-seize grease on threads. The old ones were 2 years old and looked browner but not black and sooty. I run Sierra premium blend oil through the reservoir tank, no stabilizer, regular pump gas in a 12 gallon portable tank and get 65-75 miles per tank hauling 900-1000 lbs passengers & gear @4000rpm cruising around 35mph typically on smooth salt water. Very light glass boat just under 16' similar to a Whaler hull but lighter, top speed is 49mph @ 5300rpm with me alone in it on a 13x19 SST1 prop. This oil injected motor averages about 80:1 fuel/oil ratio based on consumption.

I would back down on the oil if you are pre-mixing, definitely don't use more than 50:1. But if your motor sounds like the video motor, you have other problems. That's a cylinder dropping out.

 

[Molska]

Re: Black Spark Plugs

Wow thats a pretty plug, ya mine have never looked like that. As for the video ya my engine sounds and feels like that at full throttle.

But i did spark test, compression test, carb kit, new tank and hose, new coils so i dunno what the change next except the power pack

 

[Craig-]

Re: Black Spark Plugs

Wow thats a pretty plug, ya mine have never looked like that. As for the video ya my engine sounds and feels like that at full throttle.

But i did spark test, compression test, carb kit, new tank and hose, new coils so i dunno what the change next except the power pack

Probably is the pack then. CDI is having trouble keeping the more common ones in stock this year. I talked to a tech there last month, they attribute it to the unusually hot summer around the country. But it's hot here in Florida every summer and I sell a lot of packs every year. Some people run around on one dropped cylinder on the bigger motors and never know it until the next one goes.

 

[Craig-]

Re: Black Spark Plugs

Just for the heck of it I went out and pulled the plugs out of my own personal motor. This motor is 26 years old, and runs absolutely perfect. Nothing has ever been done to it other than change the impeller a couple of times just because.... And gear lube changes of course. And oh yes, I did change the plugs about 5 years ago because I was going to tow it 1500 miles up north on vacation. But the plugs didn't need to be changed, I just did it just because....

I will say that this motor is rarely ran at over 4000rpm. It tops out at 34 mph @ 6000rpm. (35hp)

Running L77JC4 at .040"

OK, OK, I will admit that I err on the side of too much oil. Simply because the tank won't hold a full 6 gallons + oil without being slop-over full. More like 5 1/2 gallons.

Try enough oil for 5 gallons instead of six. If the temp doesn't go up you'll be fine or switch to a synthetic blend.

 

[Molska]

Re: Black Spark Plugs

Ya the temp up here doesn't come close to being as warm as Florida consistently, but i don't know what else it could be other than the power pack. i spent enough might as well through another 100 at it. i think i'll hold back on the oil a little.

 

[boobie]

Re: Black Spark Plugs

Before you buy the power pack take your boat out on the water and run the hell out of it for about 15 mins. Then immediatly shut it down, pull the plugs and see if they look like Craigs above. If they do,there's nothing wrong with your mtr. The trick is a nice golden brown after a good hard run.

 

[Molska]

Re: Black Spark Plugs

Really do i run the hell out of it if its reacting like the video i posted? I dunno if thats wise

 

[boobie]

Re: Black Spark Plugs

Sorry but I missed the video so I just watched it. That acts like a bad ignition miss. That could be pack, coils,stator or timer base. But I'd probably go along with that pack as a shot in the dark. Have you checked out the rest of the ignition componets using a DVA meter and following the specs in an OEM manual ?

 

[Molska]

Re: Black Spark Plugs

no i haven't checked much except spark and compression which were both fine, changed plugs, coils, and did carb kit. what else should i look at besides the power pack now?

 

[boobie]

Re: Black Spark Plugs

If you haven't got the proper meter and OEM service manual for procedures and specs to check out the rest of the ignition system the best thing you can do now is throw a pack at it.

 

[Molska]

Re: Black Spark Plugs

ya i have a Clymer book but its not very detailed, theres really no way for me to know if my previous efforts have worked until i run it on the lake. But i will certainly change the power pack if the problem continues. thanks for the info