Mercury Trouble Shooting

[Tracker 1754]

I have a 40 horsepower 2 stroke Mercury Outboard and I am trying to trouble shoot an issue before taking it to the shop. I took it out a month ago and it started and idled great when I gave it full throttle it ran like it should but only for about a minute then it started to surge. By surge i mean it would maintain my desired speed then slow down then speed up, then finally at full throtle I was only doing about 10 mph. I have changed out the fuel filter and I am contemplating getting a fuel water seperator. It may have been some bad gas isnce I had the same issue with another small engine with the same gas as what I put in my boat. If I do get a fuel water seperater what is the best way to install it. I was thinking to mount it in my battery/gas tank campartment and put it between the engine and the primer bulb. My engine automatically mixes my oil so it won't affect that. If anyone has any answeres to any of my questions I'd love to hear from you.

 

[Bondo]

Re: Mercury Trouble Shooting

Ayuh,... It's either Bad gas, or a boogered up fuel system,...
The filter will be Fine where you want to put it...

 

[verado7]

Re: Mercury Trouble Shooting

start with the fuel system heres some things to check


take the boat out for a run and when this surging happens - pump the fuel primer bulb - if it improves ,now you know its lack of fuel .

shutdown the motor and pump the fuel bulb ,when its tight -hold it firmly -does it deflate? if yes . have about a 1/4 tank of fuel in the can ,pump it up again and let go and put your ear to the gas can - do you hear fuel running back in ? yes - replace the bulb -if not -definately rebuild the carbs and fuel pump some carbs have integrated fuel pumps -usually smaller than 40hp though


either way if you have 5 years or more on the carbs and fuel pump it would just be wise to rebuild them anyway -its not expensive and easy to do -