1979 Merc 80 HP missing

[npd4432]

I have a 79 Merc 80 HP 4 cyl I just transfered from a runabout to a pontoon boat. When on the runabout it ran good without a miss. Now that I transfered the motor to the pontoon it seems to have a miss at low and high speed operation. It is sometime intermittent and sometimes consistant. Here is what I have done so far. replaced plugs, took apart carbs and cleaned, fuel pump rebuild along with replacing the fuel lines. It seems as the miss will go away when I spray premix in the lower carb, so I am guessing that it is a fuel related problem. But I did take the carbs apart and clean them, they were both very clean, no signs of any contamination. It also has a pretty good idle but dies sometimes when put into gear. Any help would be appricated.

 

[npd4432]

Re: 1979 Merc 80 HP missing

Any suggestions???

 

[Faztbullet]

Re: 1979 Merc 80 HP missing

How did you lift it when swapping engines???

 

[vupilot]

Re: 1979 Merc 80 HP missing

I have similar issues with a 1975 40 hp Merc. It started after I got gas at an old fuel station so Im thinking I have bad fuel.

Hook up a portable tank with known fresh gas and try that first.

 

[npd4432]

Re: 1979 Merc 80 HP missing

How did you lift it when swapping engines???

Engine hoist, minimal movement side to side, mostly up and down with the hydraulic on the hoist.

 

[npd4432]

Re: 1979 Merc 80 HP missing

I have similar issues with a 1975 40 hp Merc. It started after I got gas at an old fuel station so Im thinking I have bad fuel.

Hook up a portable tank with known fresh gas and try that first.

It has a new fuel tank with new lines.