Johnson 6HP + fouling problems

I have a Johnson 6HP 2 stroke (1984 I think) that was first haveing trouble even starting. I cleaned out the carb. and replaced spark plugs. Had it running for a good portion of a fishing trip then it did not want to start at all towards the end of the trip. Checked spark plugs and they were fouled out. I cleaned them and tried again to start it but still wouldn't start and the plugs seem to be instantly fouling out.

If there is anything I can do to stop this fouling suggestions would be great!
Thanks

Re: Johnson 6HP + fouling problems

What plugs are you using? What gap? What fuel mix are you using?

Fouled plugs are not the cause of your problem, they are merely symptoms.

You need to find the cause. "Outboard won't start" in Engine FAQs should give you a clue or two.

We really need your model number. Look for it on the transom clamp or on a quarter size plug on the powerhead.

Re: Johnson 6HP + fouling problems

if this does not work, try opening our spark plug gap to .035 or .040, if you do a lot of slow speed running or trolling. try the first section of this. http://forums.iboats.com/showthread.php?t=167352 are you using champion plugs, these are recommended.
6, 7.5, 8, 8 Commercial 1977 - 2001 QL77JC4 or QL86C .030

Re: Johnson 6HP + fouling problems

I have a 1984 6hp Evinrude, longshaft sail version E6SLCRM (CR are the date letters for '84) Never had any problems with plug fouling.

Correct plugs are QL77J4 or L77J4 gapped at 1.0mm (0.040")

Surfaced gapped QL78V or L78V are recommended for sustained high speed use.

You should be using a 50:1 fuel mix using a TCW3 oil.

If your plugs are comming out wet with fuel then maybe the carb is flooding but I think you'd realise this anyway.

I have also used NGK B7HS-10 plugs with no difference noticed (or were they B9HS-10?)

I dont know why others are suggesting or implying the gaps might be less. 40thou is straight out of the owners manual.
.....JC4 are copper cored versions of the same plugs

Re: Johnson 6HP + fouling problems

"I dont know why others are suggesting or implying the gaps might be less. 40thou is straight out of the owners manual. "

That was in 1984, Vic. In the past 24 years the recommended gap has changed to .030"

Re: Johnson 6HP + fouling problems

What will make a lot of difference in the plugs is to make sure that the thermostat is working and that it is the correct one (143 degrees). Use BRP part number 5005440 or Mercury part MM 75692. The Mercury part is half the price and works fine.

If your plug is fouled, so is the rest of the firing chamber, so you should de-carbon the engine. Captain Dunkleberger's SeaFoam treatment works real well:
http://forums.iboats.com/showthread.php?t=158076

http://www.iboats.com/Sea_Foam_Moto...14590721--**********.130746687--view_id.37968

If you use a quality synthetic or synthetic blend oil like BRP XD-50, you will also get less fouling and XD-50 has a carbon treatment built in that will help to keep the engine clean once you decarb it.

Re: Johnson 6HP + fouling problems

In the past 24 years the recommended gap has changed to .030"

Click to expand...

Does that mean I should close mine to 30 thou if so why?

Re: Johnson 6HP + fouling problems

http://www.boatsetup.com/SparkPlugChart.pdf

Re: Johnson 6HP + fouling problems

Some people still use .040" if they troll a lot and worry about fouling, Vic.

OMC determined that the Champion plugs performed at least slightly better with the .030" gap.

Re: Johnson 6HP + fouling problems

Joe Reeves, who is very knowledgable in these matters, still thinks that .040 is the right gap. My personal opinion is that the wider gap gives a better spark when fuel quality is in question and that smaller gap may help when the quality of your ignition system is in question, as in arcing.

We have always set the gap at .040 when trolling, no matter what anyone else says.

Re: Johnson 6HP + fouling problems

Do as you please. BRP and Champion recommend .030" and so do I.