Logo
FULL SITE MENU

15 Hp Evinrude plugs keep fouling

J

joep

New member
" The plugs on my 1975 15Hp Ev

" The plugs on my 1975 15Hp Evinrude keep fouling. At first my mixture was too rich. I have purchased a measuring device so I am sure the mix is correct. I replaced the plugs, took the boat out and when I got back the plugs were fouled.

I also discovered that the plugs installed were not what the manufacturer recommends. Would the incorrect plug cause fouling? Also, anything else I should be looking for in order to prevent fouling? "
 
"Jeep..... You say you're

"Jeep..... You say you're using the wrong s/plugs but you don't say what s/plugs you're using. Wrong s/plugs would have a tendency to foul quickly. The correct spark plugs would be Champion UL81J plugs with the gap set to .030.

Joe
"
 
" Joe,

I was using a Champi

" Joe,

I was using a Champion QL77JC4. My manual says I should use theChampion UL81J as you recommend. My local auto parts store carries Autolite and they cross referenced the Champion with a Autolite 4092.

How about the Thermostat? Should I change it? Is that a simple process? Thanks for your help. "
 
" Sparky,

How can I tell if

" Sparky,

How can I tell if the thermostat is stuck open? The engine runs well and it does not seem to be getting too hot. Thanks. "
 
"Have you taken a compression

"Have you taken a compression test? It could also be bad rings. I had the same problem with my 9.9.
Also are you running the motor to go somewhere or just trolling all the time? This will also make a difference as whether the plugs foul & the type of plug you need. The ones you are using are near what you need for that older motor that uses points instead of a CD ignition, as the 78 series tend to not fire as well if the coils or condensers start deteriorating, & they get oil fouled.
Take a look at the web page I made up for our fishing club http://www.pugetsoundanglers.org/Fishing%20Info/Johnson%209.9_15.htm
I am not an OB mechanic, but have worked on my own motors for over 40 years & this us from my own personal expeience & from what I gleaned off these web message boards over the years.
Hope this helps."
 
" Machinist,

I use the engi

" Machinist,

I use the engine for duck hunting. I run it mainly wide open in cold weather. Thanks for the info. on your web page. I will be sure to read it. I think the compression is OK becaues when the plugs are not fouled the engine runs well. Thanks again. "
 
Back
Top