1985 Mariner 150 FOULS plugs everytime?

[imthemedic]

My Mariner outboard is fouling plugs like crazy. The plugs look like used auto motor oil is all over them. It does this everytime i run the motor. It smokes more than normal and seems to have a miss on the top end, you can feel it surging. It seems to pull hard out of the hole all the way up to top end. If i keep it wide open for 2 or 3 miles it will stall out and wont start back. The plugs have to be cleaned and a little shot of gas in the cylinders to get it started again.
History: Last year I seized the motor on the lake. The water pump went out and the buzzer didnt work. I froze the top two cylinders. The motor has two new sleaves and 6 new pistons. It was rebuilt by a local marine shop. I got the boat out this year and it wouldnt run. The carbs had gas pouring out of them. The carbs were just rebuilt with new needle and seats. I also replaced all the fuel lines,bulb,filter, added new gas. The oiler has been removed and I pre mix the oil at 50 to 1. This brings us up till current time. Now it is fouling plugs? However when it is running it is better than ever before LOL. Any HELP out there?

 

[Chris1956]

Re: 1985 Mariner 150 FOULS plugs everytime?

Check your fuel pump diaghram. If they leak, raw fuel will get into the crankcase and foul plugs or worse.

 

[imthemedic]

Re: 1985 Mariner 150 FOULS plugs everytime?

What is the easiest way for me to check that? Also I am using NGK Plugs. I have noticed when I look into the cylinders the tops of the pistons seem to have a lot of carbon build up. Their not clean and shiny like my snowmobiles are.

 

[j_martin]

Re: 1985 Mariner 150 FOULS plugs everytime?

There's a pulse hose to the crankcase from the fuel pump. It should not have any fuel in it.

The floats may have all been set too high. Also, in that year the floats may have been foam. They have all sunk since then from the alcohol in the fuel.

The fuel lines also may be disintegrating if they are the original ones, putting pieces of chit into the needle valves and holding them open.

Sounds like when you get the carbs right, it'll be a real mover.

hope it helps
John

 

[honestcharlie56]

Re: 1985 Mariner 150 FOULS plugs everytime?

make sure that the plugs you are running are what the engine calls for, alot of people seem to just throw any type of plug in and that causes all kinds of problems, i hope this at least helps, but also as someone said early, i think if the pulse line gets fuel in it or leaks it will effect fuel delivery. good luck man

 

[imthemedic]

Re: 1985 Mariner 150 FOULS plugs everytime?

The fuel lines were replaced from the tank to the carbs. I put new plugs in NGK BU8H in and Decarbed it with seafoam and a gallon of gas. Did this today and no help same problem. Oh and I put new gas and oil in it as well. I didnt notice any gas in the line between the pump and crankcase. Any help?

 

[Chris1956]

Re: 1985 Mariner 150 FOULS plugs everytime?

I guess the next task is to rebuild the carbs. Make sure the floats are in good shape and their height is set correctly.