60hp mariner slow down

[nasherfish22]

i have 1996 mairiner bigfoot after running about an hour it will drop rpms from 5500 to about 3000 and will fluxuate.all the sudden picks back up then drops off. after awhile of being shut off it runs fine then stats doing again.any idea will help brand new water pump assembly installed a new gas tank and line all filter are clean that was taller. i have no idea whats going on please help thank you.

 

[Silvertip]

Re: 60hp mariner slow down

Look at the primer bulb in the fuel line when this happens. If it is being sucked flat (not just soft as that's normal) then there is a fuel restriction between the bulb and the bottom of the pickup tube in the tank. You said this is a new fuel tank. If this is a new portable (6 gal) tank, was it replaced due to this problem or did the problem start "after" the tank was installed. If it is a new plastic tank, drain it and look for small plastic particles inside. I've had those small bits plug up on one of my own tanks. I also look inside brand new tanks at the various stores and many of them have varying amounts of this stuff. The restricted fuel flow causes the carbs to empty, then fill, then empty, then fill repeatedly. That also means the engine is running lean which can cause permanent damage so get this issue resolved quickly. You may also have a weak fuel pump.

 

[joed]

Re: 60hp mariner slow down

Some engines have a shutdown when the engine overheats. It still allows you get home cripple but it help save the engine. Not sure if that engine has this feature but sure sounds like what happens when it kicks in.

 

[nasherfish22]

Re: 60hp mariner slow down

thanks for the response the tank is a 19gal tank and the primer bulb is soft and i was going to replace the fuel pump this spring as well as clean the carbs but now i will also clean the tank as well, thank you. as for running hot the stream out the back is cool water coming out so i dont think thant the problem.