'68 65 HP VXL-14B fouls plugs, won't idle

[Justwanttohavefun]

Recently purchased an old glass boat (pretty nice!) with an old 65 Johnny VXL-14B on it (V-4). Seems like maintenance has always been excellent on this boat & motor. Starts a little hard when cold. Runs great at WOT, but it won't keep running run at idle so no wake zones are no-go zones (this is a problem). Plugs foul, then starting is a nightmare. Plugs are new, and cleaning them gets me relief, but just for a few minutes. I just cleaned the carbs, but they didn't seem bad except for a little whitish crud. I'm using good oil (valvoline), fresh gas. Any ideas?

 

[HighTrim]

Re: '68 65 HP VXL-14B fouls plugs, won't idle

Which plugs are you running? Have you checked the compression on the motor? What mixture are you pre mixing at? Are the plugs simply black, or wet with carbon, or more of a black with soot?

 

[Justwanttohavefun]

Re: '68 65 HP VXL-14B fouls plugs, won't idle

Thanks for your reply. I'm running 50:1 mix, adding sea foam and CRC fuel stabilizer (ethanol fixer) to 87 octane regular. Plugs are NGK B7HS10.

A few tims I've observed actual wetness on the plugs - oily spots - immediately after use. Mostly though plugs are just on the dark side, with a little crispy black deposits.

 

[Justwanttohavefun]

Re: '68 65 HP VXL-14B fouls plugs, won't idle

I haven't checked compression yet (mostly because I don't have a compression tester).

 

[ezeke]

Re: '68 65 HP VXL-14B fouls plugs, won't idle

Your engine will probably be happier running on the recommended Champion spark plugs: L76V surface gap.

Make sure that your thermostat is working properly and keeping the engine at the right temperature. It is very hard to avoid carbon on a cold engine.

You will get less carbon if you use the blended or full synthetic TC-W3 oils because they have a higher flashpoint.

BRP XD-50 has a carbon treatment built in which will help to keep the carbon down after you do your de-carbon treatment:
http://forums.iboats.com/showthread.php?t=158076

 

[Justwanttohavefun]

Re: '68 65 HP VXL-14B fouls plugs, won't idle

Excellent - thanks for the ideas .I'll pick up a set ofChampion plugs and will try some synthetic. I'll be on the lake all week, so I'll definitely be running it as much as it will go. I'll let you know how it works out.

Thanks again!

 

[Justwanttohavefun]

Re: '68 65 HP VXL-14B fouls plugs, won't idle

Wow - just reviewed the decarb treatment information and this sounds like it might be the issue. I'll definitely give it a try. Gotta wonder just what this seafoam stuff is exactly. BTW, how do you verify the thermostat is operating properly?

 

[HighTrim]

Re: '68 65 HP VXL-14B fouls plugs, won't idle

Follow the advice given by Ezeke. You can test the t stats by submerging them in a hot liquid, monitored by a thermometer to determine when they open and close, but personally, if I am going to pull my t stats, Im putting new ones in along with a new gasket.

Decarbing with Seafoam is a great annual maintainance item. Then treat your fuel with if afterwards.

I would also ensure that your ground for the igniton is clean and tight. Take a file to it, then retighten.