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1985 40HP Mariner FuelCarb problems

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wperry

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"I have a 1985 40HP Mariner- n

"I have a 1985 40HP Mariner- not sure what is going on. When I crank the engine it will not stay running for very long. If I throttle it up it will stay running but it spits and sputters. I have unburnt fuel coming out of the exhaust (a grey goo)The thing is I have noticed that when I unplug the fuel line at the motor after about three seconds the motor will start to run perfectly (reve and idle) and no unburnt fuel out the exhaust! I then will plug the fuel line back on and in about three seconds it will start spitting again. It is like bogging the motor down or loading up to much fuel. I pulled my fuel lines and I found a pin hole in one of them (thinking this was the culprit) so I replaced all of the fuel lines. This did not help. I had just rebuilt my carbs last fall and it had been running fine up until this May when this started.I have just finished rebuilding them again and it still is doing the same thing. I am stumped. Good compression on both cylenders and good spark on both. I love this motor! I do not want to give up on it. It will run like a bat out of hell when its running right. Any helpful advise would be deeply appreciated. Thanks in advance,
Wilson Perry
P.S.- Also my top plug seems to fowl."
 
"with engine off, pump the fue

"with engine off, pump the fuel bulb, look down the carb or carbs with the engine in its normal position. You should see no fuel dripping out inside the carb. I suspect the float is stuck. The engine runs better with the fuel line disconnected because it is burning the excess fuel in the engine untill it runs out of fuel. Standard crap in the carb or the fuel has gone bad."
 
Thanks for getting back so qui

Thanks for getting back so quickly. I am using fresh gas. I can pump the bulb and I will get a little gas but not much (very little)in the top carb. I have thought that it was the float sticking but I have taken the carbs apart at least six times in the past two months two recheck everything. I have checked the O rings on the float valve seat and they are good. That was a past problem where one had gone bad and fuel was pouring out of the vent hole when you pumped it up. I am thinking that somehow that gas is passing through the seat but I can not figure out how.
 
"OK I thought about the fuel p

"OK I thought about the fuel pump also so I have taken it apart this afternoon and cleaned and checked it and all the seals and while I was at it I pulled the carbs and checked and recleaned them. I don't think that it is the fuel pump because there is a T right after the pump that goes to both carbs and it is just the top cylinder that seems to not be burning the fuel or loading up with fuel or it is the only cylinder that keeps fouling the plug. After putting them back together I cranked it and the same thing happens. When I pump the bulb I now have no gas bi-passing the seat into the carb. The one other thing that I was thinking is could it be that the top reed valve has failed? (Hope Not) I looked today and I could see the one on the top when I had the carbs off and took a long Q-tip and could gently open and close it. It did not seem to have any obstructions around it. It opened and closed and sealed well. After cranking it and it was still spitting out unburnt fuel I put a spark tester on each plug and they glowed the same. I have replaced the CDI box, main coil, wires and plug caps to no avail. Could it be that even though I am getting a spark that it there is not enough voltage to the top plug from the pulsar? I know that there is only one wire that leads from the pulsar to the CDI and I would think that if it was the pulsar that both plugs would not be firing correctly. I have gotten my manual out and my meter and all of the specs are with-in range. I still am stumped.
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did you ever sort your problem

did you ever sort your problem? i had the similar with my 40 and all i did was adjust the timing and its been fine since.
 
Thanks Dane- No that is the on

Thanks Dane- No that is the only thing that I have not done. I am planning on adjusting the timing when it gets a little warmer. It seems pretty simple to do from reading my manual. Is there anything special I need to know about? Did you have any problems getting it adjusted?
 
"Hi Wilson,
adjusting the tim

"Hi Wilson,
adjusting the timing was easy..just dont be to agressive on the set screw. make fine adjustments if you retard the timing too much the motor will simply die..advance should lift your rpm`s. and having the manual as i guide will help a bunch i had to do mine blind ,i set mine by ear one day on the water. when i checked it with the T-light i was a meer half a degree out. P.S try and do this either in a drum of water or on the lake..the back pressure on the exhaust plays a role. (also easyer on the ears)"
 
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