fouling plugs on proper mix ratio

[rstreckjr]

I don't know why this is happening maybe you guys could help me out. 1978 rude 140 model #140840c. Running at 50:1 ratio. After about 3 hours of running engine through full range of rpm's I end up fouiling out all 4 plugs. I have change the fuel filter, the fuel/water seperator, multiple times for both with no change, still fouling. If anyone has any fresh ideas please help.<br /><br />Rob

 

[tmcalavy]

Re: fouling plugs on proper mix ratio

If they fouling is black, you might try a hotter plug...go up the heat range and see if that fixes it. If not, maybe time to decarbon with some seafoam or deepcreep.

 

[rstreckjr]

Re: fouling plugs on proper mix ratio

Ok, they are fouling black, I will go hotter. Do you think it would be ok to go hotter on the heat range while doing the decarbon at the same time? Or do you think I should just try one then the other?

 

[Dhadley]

Re: fouling plugs on proper mix ratio

Let's start at the begining and make sure you have the correct plug. What plugs are you running now?

 

[byacey]

Re: fouling plugs on proper mix ratio

Carb running rich will cause same problem, possibly and most likely due to a leaking float needle and seat, or a sticking float.

 

[rstreckjr]

Re: fouling plugs on proper mix ratio

Dahadley: <br />I am using L77JC4 plugs.<br /><br />Bill Yancey: <br />How would I be able to tell if the Carb is running to rich? Also, is there a way to tell if the float needles are leaking? Please pardon my arrogance I don't anything about Carbs, the rest of the motor I can handle, but Carbs confuse me...<br /><br />By the way everone, Compression checked good on all 4 cylinders, They were between 124 and 128. Coils are sending good spark to the plugs.

 

[Dhadley]

Re: fouling plugs on proper mix ratio

Good choice of plugs. When you say they foul after 3 hours running, what do they do or not do? Or are you just seeing them turn black?

 

[byacey]

Re: fouling plugs on proper mix ratio

There are various ways to check the needle and float, but the easiest way is to just replace them and inspect the float. Needle and seat are very inexpensive.

 

[rstreckjr]

Re: fouling plugs on proper mix ratio

Dhadley: <br />The motor sounds like the plugs are fouled like it is straining to work. I also have an extreme loss of power ( i.e. going from 48mph to 7.5 to 8.5mph ). At that point I have learned to change the plugs on the water and whamo I'm running strong again. The plugs I pull out are black and are heavily coated in oil.<br /><br />Bill Yancey: <br />Thanks for the info, I will look up the part numbers for the needle, float and seat and get them on order.