c60tlrx continues to foul plugs

[dale3]

I bought a 1999 Yamaha C60tlrx 1 year ago. It ran good first time out. After a couple of weeks use (mostly week-ends) It started cutting out and no hole shot. The bottom plug was wet and I replaced it. Motor ran good for several months and then the cutting out occurred again. This time the middle plug was fouled. This week-end the bottom plug fouled again, motor ran poorly untill I replaced the plug. Any ideas on why the motor is fouling spark plugs.

Thanks,

 

[robert graham]

Re: c60tlrx continues to foul plugs

Probably a bad fuel pump diaphragm sucking fuel directly into crankcase causing rich mixture, plug fouling, poor gas mileage. New fuel pump about $45 on line, 2 screws, very easy fix. Good Luck!

 

[dale3]

Re: c60tlrx continues to foul plugs

I replaced the fuel pump diaphrams yesterday. Will run motor Friday. I guess it will take a while to see if the fuel pump was casusing plug fouling?
Thanks for help.
You know, I thought this motor seems to use a lot of fuel compared to previous motor on same boat. I had a 85 hp merc.

 

[robert graham]

Re: c60tlrx continues to foul plugs

If it was the bad fuel pump diaphragm, the motor should run better, cleaner, no plug fouling, better gas mileage. Is your gas fresh? Old gas will definitely foul plugs. Maybe you should drain each carb(brass drain plug) to check for water/debris in float chambers, it's a very easy job and a great idea to do at least a couple of times per year.

 

[dale3]

Re: c60tlrx continues to foul plugs

I went fishing Saturday. The motor ran the same. It definitley has fresh gas. I use the motor a couple of times each week. Seems like when I have to idle for extended distances, like thru some stumpy areas and then try to get on plane the motor stumbles and then catches and runs good.
I pulled the carburetors yesterday and went thru each one. I saw no debris no gummy deposits. I did blow each passage out with air and re-assembled. I guess I'll use the motor and see if I foul another plug.

Thanks for suggestions

 

[robert graham]

Re: c60tlrx continues to foul plugs

What kind of shape are your spark plugs in? Any fine cracks or deposits on center electrode insulator? If a plug is not in very good condition to start with, then some idling can cause this "fouling" situation. I use a small spark plug sand-blaster from Harbor Freight to clean plugs right down to the bare, white porcelain insulators. If you install brand new plugs how long does it take to foul? I really think that bad fuel pump may have been the problem. Good Luck!

 

[dale3]

Re: c60tlrx continues to foul plugs

Well it's been about 4 weeks later and about 5 trips to the lake. The motor has fouled 2 more spark plugs. The middle and bottom plug. Top cylinder has always been OK. I have been through the carburetors and replaced the fuel pump diaphrams. Still puzzled as to why the plugs foul. It seems that the motor doesn't like to be idled for very long stretches. I am not talking about real long. Simply through a stump field that might take 10 minutes. Any more ideas would be appreciated.

 

[robert graham]

Re: c60tlrx continues to foul plugs

A rich mixture, old stale gas, heavy oil mixture, could foul plugs. It might help to run motor wide open for a while to burn off old oil and carbon. Are you using the 50:1 oil ratio? I use the Pennzoil 100% Synthetic Outboard oil for less smoke and carbon. Are your plugs good and clean to start with? Do you have the correct plugs in the motor? A different heat range plug could definitely cause fouling. Maybe check your owners manual for the recommended NGK plug. Good luck and let us know how you do!

 

[99yam40]

Re: c60tlrx continues to foul plugs

It took me a year or so to finally find out a previous owner had drilled out the jets in my C40TLRX. It was not fouling plugs but would drop a cylinder at WOT.

Did you disassemble the carbs completely and clean?
Did you do a link and sync like the manual says?
Check to make sure the jets are the proper ones.
There are different size jets in the different carbs so pay attention where all parts come from.

What do the plugs look like when they foul out?
What oil are you using and are you adding ringfree?
like Robert said are the proper plugs in the motor?

 

[boben2830]

Re: c60tlrx continues to foul plugs

Make sure you fuel / oil mix is exact. Avoid idling for too long. You may have worn rings / cylinder walls. If this motor has gotten hot or ran with the wrong fuel / oil mix this could have caused severe wear. Good luck >>

 

[robert graham]

Re: c60tlrx continues to foul plugs

Again, check for proper plugs, the previous owner may have just put any automotive plug that looked similar, if heat range is wrong then plugs can foul.