Need Help! 10E75R fouling bottom plug (update, water on plugs?)

[ntoracn@yahoo.com]

I bought this 12' Sears boat with a 1976 9.9 outboard. My first trip out on the lake resulted in the bottom spark plug fouling after 10 min. of running time. I thought I had a driver coil issue, so I replaced it , new coils,gapped the points at .020", replaced the condensors and replaced the L77JC4 spark plugs with fresh ones.<br /><br />Today I take it out on the lake and have the same problem but now it will run for 15 min. befor it fouls the bottom plug. I replace the plug and I'm up again for 15 more min. ARGH!!! <br /><br />Then I found that if I turned the idle mixture screw all the way in (lean) at wide open throttle, I can run for 20-30 min and not foul the plug. So I pull the carb thinking I have a bad float (no, but it's cork) or the previous owner installed a larger jet (no, it's the stock .051").The float looked fine also<br /><br />What is going on with this motor!!! Why is the lower spark plug the only one that is fouling?<br />I did a compression test and had 80 psi on both cyls. <br /><br />Could I have a bad reed? I don't think so as I have no fuel blowing back out of the carb.<br /><br /> As a automotive tech, this is really getting me mad. I'm about to make a boat anchor with this thing. I will take ANY advice, PLEASE!<br /><br />Thank You.

 

[Reel Appeal]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

Hi Randy,<br />Look on page 6 for dgassy post on '75 Johnson 9.9 spark leak....

 

[ezeke]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

aforementioned thread

 

[ntoracn@yahoo.com]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

Thanks for the help.<br /><br />I was keeping up with that post as I was trying to fix mine. I don't have any spark leaking. I have the bottom cylinder fouling plugs. <br /><br />I have replaced the following: new driver coil, new ignition coils, condensors, spark plugs (L77JC4), cleaned all the groung connections.<br /><br />I have the stock 9 1/4 X 10 prop. With the wife and kids in the boat, the motor won't pull max RPM at wide open throttle (due to weight), but will still rev to 3,800 to 4,000 rpm (by ear). Am I lugging the motor with this prop and causing the plug to foul? IF so, why does the bottom cylinder only foul?<br /><br />My first boat owning experience has been dissapointing to say the least. These motors are sooo basic, I don't get it.

 

[ntoracn@yahoo.com]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

anyone have ANY ideas?

 

[ntoracn@yahoo.com]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

I'm gonna start mixing some concrete. What about prop pitch, see me new post above.

 

[caveguy]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

Originally posted by Randy Castleman:<br /> I bought this 12' Sears boat with a 1976 9.9 outboard. My first trip out on the lake resulted in the bottom spark plug fouling after 10 min. of running time. I thought I had a driver coil issue, so I replaced it , new coils,gapped the points at .020", replaced the condensors and replaced the L77JC4 spark plugs with fresh ones.<br /><br />Today I take it out on the lake and have the same problem but now it will run for 15 min. befor it fouls the bottom plug. I replace the plug and I'm up again for 15 more min. ARGH!!! <br /><br />Then I found that if I turned the idle mixture screw all the way in (lean) at wide open throttle, I can run for 20-30 min and not foul the plug. So I pull the carb thinking I have a bad float (no, but it's cork) or the previous owner installed a larger jet (no, it's the stock .051").The float looked fine also<br /><br />What is going on with this motor!!! Why is the lower spark plug the only one that is fouling?<br />I did a compression test and had 90 psi on both cyls. <br /><br />Could I have a bad reed? I don't think so as I have no fuel blowing back out of the carb.<br /><br /> As a automotive tech, this is really getting me mad. I'm about to make a boat anchor with this thing. I will take ANY advice, PLEASE!<br /><br />Thank You.

 

[caveguy]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

Originally posted by Randy Castleman:<br /> I bought this 12' Sears boat with a 1976 9.9 outboard. My first trip out on the lake resulted in the bottom spark plug fouling after 10 min. of running time. I thought I had a driver coil issue, so I replaced it , new coils,gapped the points at .020", replaced the condensors and replaced the L77JC4 spark plugs with fresh ones.<br /><br />Today I take it out on the lake and have the same problem but now it will run for 15 min. befor it fouls the bottom plug. I replace the plug and I'm up again for 15 more min. ARGH!!! <br /><br />Then I found that if I turned the idle mixture screw all the way in (lean) at wide open throttle, I can run for 20-30 min and not foul the plug. So I pull the carb thinking I have a bad float (no, but it's cork) or the previous owner installed a larger jet (no, it's the stock .051").The float looked fine also<br /><br />What is going on with this motor!!! Why is the lower spark plug the only one that is fouling?<br />I did a compression test and had 90 psi on both cyls. <br /><br />Could I have a bad reed? I don't think so as I have no fuel blowing back out of the carb.<br /><br /> As a automotive tech, this is really getting me mad. I'm about to make a boat anchor with this thing. I will take ANY advice, PLEASE!<br /><br />Thank You.

 

[bubbakat]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

It might be flooding the cylinder with to much gas. Check your flaot in the carb and see if maybe it is flooding .<br />Just a thought.

 

[caveguy]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

I had the same problem with my 60HP Nissan. Check the fuel pump diaphram for exess wear or other damage. A small enough leak will not have much effect at high revs but may be enough to foul things up at lower or mid revs and especially at idle.

 

[ntoracn@yahoo.com]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

Thanks Cave Guy and Bubbakat. I took the carb apart last night again, and everything look fine.<br /><br />I did take the fuel pump off and took it all apart, everything looks fine. <br /><br />I took all ground wires off and cleaned them and I checked the resistance on all primary ignition wires for improper resistance, nothing looked abnormal!!!<br /><br />This thing is so weird, I'm at a loss for what to do now.

 

[CorB]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

I had a problem with the fuel gauge in my portable gas tank. It had a float of cork, but didn't want to float in the gas. I've read somewhere that cork possibly will not float on the gas they use "nowadays". You might want to check the float separately in some gas and see if it really floats. It's just a thought, didn't had the same problem as you have myself.

 

[ntoracn@yahoo.com]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

OK, I decarboned the motor with "deep creep". The compression came up to 92 on the bottom cyl and 82 on the top one. I then installed new plugs and ran the motor in a tank for an hour at no more than 1/3 throttle (if I went more, water started splashing out). I can get it to idle real well and if I run the mixture leaner at higher throttle, I can make it run very smooth (thats a good thing) and not foul plugs. <br /><br />But when I pulled the plugs to look at their color, I seen a very small amount of water on the inside of the spark plug? Obviously water is getting into the cyl. from the head gasket I assume? I think this might be part of my spark plug fouling problem? Will I hurt the motor if I use it this way for the weekend?<br /><br />I'm sorry for so many posts earlier in the week, I just have 2 major trips coming up (one this weekend) and was looking at trying to get my boat reliable so I could feel confident on taking the wife and kids out on the lake. <br /><br />Thanks

 

[Reel Appeal]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

http://www.pugetsoundanglers.org/Fishing Info/Johnson 9.9_15.htm

 

[voodoo]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

Pull the head, resurface the head on a flat surface with fine sand paper (or machine it flat) and replace the head gasket.<br />If the leak is bad enough it will eat the piston and cylinder.<br />You will be able to tell alot from reading the piston and walls.

 

[ntoracn@yahoo.com]

Re: Need Help! 10E75R fouling bottom plug (update, water on plugs?)

Thanks guys,is it possible for the exhaust plate or cover to let water get into the combustion chamber? If I go and get some gaskets today, I will try and get it repaired tonight.