25 Merc 2 stroke junk

[Mainetroller]

I need help. I have a 1989 merc 25 hp 2 stroke outboard, longshaft. It has very low hours and great compression and spark. The motor sat unused for a number of years. I have had it worked on by 2 dif dealers and im sorry to say the origonal prob has never been fixed and im confused as to why a merc dealer could not solve my prob. The boat runs and turns up fine in the yard. After the work heading out to fish i start the boat and it runs good until i set out and get on plane. Then it basically dies out and will not run after. this motor is in pretty much new condition. the carb and fuel pump have been gone thru, spark tests good. ive already spent a bunch of money having it looked at and at this point im ready to dump it. The only thing i can come up with is maybe a new fuel tank an line? i have cleaned out the tank i have and put new lines in and on it. Maybe the connection at the motor? somebody please help me out i want to get out fishing.

Thank you
MaineTroller

 

[oldman570]

Re: 25 Merc 2 stroke junk

It could be something as simple as the tank not venting as it should or the motor carb is set to lean or rich and the motor is flooding or overheating or the timming is off, an fast. The timming setting and carb setting need to be done in a test tank or on the water for everything to be set correctly. The manual will state so, and only gives start settings to get the motor to run then goes into more detail as to the fineal setting while on the water. This could be your trouble. JMO
Oldman570

 

[Faztbullet]

Re: 25 Merc 2 stroke junk

25 Merc 2 stroke junk

Your correct...just pm me and I'll give ya $150 for it for parts!!!


Now to be serious try another tank or remove end and stick down in tank as you could have debris in pickup. When it quits will it restart and idle ?

 

[Mainetroller]

Re: 25 Merc 2 stroke junk

yes it will usually start back up and idle but run choppy

 

[Mainetroller]

Re: 25 Merc 2 stroke junk

somebody asked me today about the thermostat/water pump switch? is this nonsense or might this be the problem?

 

[MH Hawker]

Re: 25 Merc 2 stroke junk

Its sucking air into the fuel system some place.

 

[colbyt]

Re: 25 Merc 2 stroke junk

You are opening the tank vent?

 

[Mainetroller]

Re: 25 Merc 2 stroke junk

Yes

 

[joed]

Re: 25 Merc 2 stroke junk

Have you checked the tank? I saw one tank once where the drop tube inside the tank was bad. This was a potable tank.

 

[CharlieB]

Re: 25 Merc 2 stroke junk

When you replaced the fuel hose, did you replace the quick disconnect fittings? Often the O-ring inside the fitting will fail to seal well when under vacuum by the fuel pump and allow air to be sucked in. That leaky O-ring can seal perfectly when pressurized by the priimer bulb so it can be a P.I.T.A. to figure out what's wrong.

You can temporarily substitute a clear hose in place of the fuel hose immediately before or after the fuel pump, run the motor and watch for air bubbles passing thru the clear hose indicating a leak.

Just remember to remove that clear hose once finished testing and repaired as clear hose is NOT RATED nor approved for fuel use.

 

[Laddies]

Re: 25 Merc 2 stroke junk

The high speed winding is bad in the stator, don't curse the motor because someone took it to a idiot for service

 

[quicktach]

Re: 25 Merc 2 stroke junk

Remove the carb and clean it. Set float correct. Tighten back on securely. Do a link & sync afterward. New fuel filter on engine.