1984 35 hp Mercury Outboard still dead

[rooster519]

I'm about to give up on this motor. I replaced the switchbox, checked all electrical connections, cleaned the carb and rebuilt the fuel pump. If the motor sits for a day or two it will fire right up and run for about 15 seconds then die. It is like the motor is flooding itself. The gas is new (as of a month ago) so I don't think water could be the problem. I have great spark on both cylinders. When I'm priming the motor the squeeze bulb never get's hard but I do see fuel in the carb and I can get fuel to spray out of the bowl over flow. The motor spins freely without the spark plugs in and compression seems normal when spinning by hand, however, I have not done a compression test on the cylinders. The fact that it runs for a couple seconds makes me think that compression shouldn't be the problem. Any ideas??? Thanks for all your help!!!!

 

[oldman570]

Re: 1984 35 hp Mercury Outboard still dead

You need to recheck the float level of the carb as gas should not flow freely from the carb as stated. If the float level is to high the carb will flood the cylinders, and if set to low it will not let fuel into the carb as it should. The inlet needle and seat might need to be replaced if in bad shape or sticking, and will not shut the fuel flow off. Use of a portable fuel tank and prime bulb to supply fuel to the carb while the carb is off the motor will let you get the float setting correct and saves work of taking the carb off and on the motor all the time. JMO
Oldman570

 

[rooster519]

Re: 1984 35 hp Mercury Outboard still dead

I removed the carb and you were correct the float was not going up far enough to close off the inlet valve. Do you know if there is any easy way to get the correct setting? It seems like it is either it doesn't let enough in or it let's too much in. Thanks for the input.

 

[carholme]

Re: 1984 35 hp Mercury Outboard still dead

Here is a link to the condensed version of the Clymer manual. Download it soonest to your computer as the link is short lived.

Small Engine Repair Reference Center Home: MERCURY - TWO-CYLINDER MODELS.

See float adjustment fig M10-2 on page 226 and following write-up.

Gerry

 

[rooster519]

Re: 1984 35 hp Mercury Outboard still dead

Thanks for that link. I got the motor running. Once I got the carb set close I had to throttle the motor up and it started right up. I let it run for about 10 seconds while moving the throttle around. It never would sit in neutral at idle. I went and hooked the ears up and let it run a while longer. Had to start at WOT and eventually the carb flooded itself out again. I removed the carb and finally got it set correctly without the manual, but I will double check it. It started right up and ran wonderfully. Sounded strong. One issue I did notice was no water coming out of the water hole on the upper part of the motor. The impeller was replaced about 5 years ago so I'm having a hard time thinking that is the problem. I was wondering, could it be clogged since the motor has sat for almost 3 years? How do I go about trouble shooting the water problem? Thanks guys!!!

 

[MH Hawker]

Re: 1984 35 hp Mercury Outboard still dead

A trick I use is, once I find out what the correct measurement is I make a poster paper templet and use that. I cut a piece that will go from side to side of the carb, and cut out the center part at the correct height to allow it to go over the floats. I just find it easier to set them.

 

[carholme]

Re: 1984 35 hp Mercury Outboard still dead

You can check the P hole by shoving a piece of lawn trimmer line up there to see if mud daubers have built a nest as they love to get in there. If that is clear and seeing that you haven't changed the impeller for five years, I would at least get in there and have a look at it and while you are there check the rest of the pump, plate and housing for wear. A $20 impeller is pretty cheap insurance.

Gerry

 

[oldman570]

Re: 1984 35 hp Mercury Outboard still dead

You will save yourself money if the motor has set that long to go ahead and replace the water pump as needed. I normally change them out after two years even if the motor has been run. They are just like the oil in your car, and wear and age takes its toll. JMO
Oldman570

 

[rooster519]

Re: 1984 35 hp Mercury Outboard still dead

Thanks for all your help. I went ahead and ordered a whole new water pump kit for it. I figured, if I'm going to be in there might as well save myself a possible headache and replace all the seals and wear plates too. Thanks again for all of the advice. I'll let you know how it all comes out!!!