Mercury help

[Chris44]

hello all I have an 86 mercury 25 2 stroke pull start. I'm not the smartest person when it comes to boats but have a little experience with motors in general. So I bought this Jon boat with the motor listed above, and this where I am at... it will start up on the first pull but wont stay running for more than a few seconds before it cuts off. I've had it out in the water a few times and had it running like a dream until it dies on me it's very hit or miss we've cleaned the carb at least 5 times adjusted the idle, changed spark plugs checked the reeds and I'm at a loss, I just need it to start idle, slow medium fast and reverse you know like a normal motor. Any suggestions would be greatly appreciated.

 

[Scott Danforth]

check to make sure your fuel is actually fuel

 

[tommarvin]

I agree carbs are frustrating.If your boating budget can buy four stroke EFI you should,
No disrespect, did you clean the carb,s like the you tube videos, did you remove the welch plug and clean the idle air and idle gas, for some reason its harder than it looks, you may need some gaskets for air leaks.
Lets assume the carb and fuel system are perfectly clean,
It sounds like a failing ignition part another slow dieing ignition that works then it doesnt when it gets hot which part i dont know if the fuel system and carbs are clean i dont know which part, if she runs like a dream and dies thats got to be a working not working ignition part.
Its better if the motor just dies so you can fix it verses a slow death it runs then it doesnt run very frustrating.

 

[GA_Boater]

Regardless of what Mr. Tom says - If the bulb is squeezed after it starts, will the motor run?

It may the fuel as Scott said, but it may be the fuel pump or both. Are you running ethanol gas?

 

[Scott Danforth]

I agree carbs are frustrating.If your boating budget can buy four stroke EFI you should,
No disrespect, did you clean the carb,s like the you tube videos, did you remove the welch plug and clean the idle air and idle gas, for some reason its harder than it looks, you may need some gaskets for air leaks.
Lets assume the carb and fuel system are perfectly clean,
It sounds like a failing ignition part another slow dieing ignition that works then it doesnt when it gets hot which part i dont know if the fuel system and carbs are clean i dont know which part, if she runs like a dream and dies thats got to be a working not working ignition part.
Its better if the motor just dies so you can fix it verses a slow death it runs then it doesnt run very frustrating.

not everyone can afford an EFI motor. they are not the greatest thing since sliced bread, when they fail, they cost you nearly the cost of a new motor to fix.

you really havent added anything in your recent post other than negativity

carbs are quite simple, and most of the problems with carbs is lack of maintenance.

regarding the OP's issue, seriously doubt its a failing ignition part. most likely its crud in the fuel system (water or dirt). however neither of us have enough information from the OP to answer that question. all we know is that it runs for a few seconds and dies. if it was ignition, it wouldnt re-start. ignition problems would not allow it to re-start and run for another fw seconds. thats a fuel supply issue, and Tom, if you had any knowledge of internal combustion motors, you would know that.

 

[DeepCMark58A]

Has the fuel pump been rebuilt? It is easy and relatively cheap, use genuine mercury parts and also replace the 2 check valves as well.

 

[Chris44]

Thanks all. Ive been out of town the last couple of days going back home to work on it now gotta get it ready for duck season we have broken the carb down to just pretty much the guts of it but I'm sure wmissed something it's an old boat I don't know much of the maitnence history I just believe I'm getting the brunt of it now but I'm going to try to fix

 

[tacx]

Just a shot in the dark here, but check your fuel tank vent . If its partially pluged it will give you those symtoms.