25hp 4stroke Yamaha idles but won't do anything else.

[don25hp]

Inherited boat with 2001 4 stroke Yamaha f25elhz. Motor starts and idles but will not do anythind else. Did the carb soak and cleaning and rebuild kit no help. Replaced fuel filter and bulb. Bulb does not get firm?? Idles but any gas and it wants to die. I can move the throttle back and forth and it will keep running but aways trying to die. Compression is good at 124 each. Any help would be great.

 

[99yam40]

Re: 25hp 4stroke Yamaha idles but won't do anything else.

Sounds like fuel pump is leaking if the primer bulb will not get firm or the needles are not seating.

Trash or dried up fuel residue and old fuel will flow into the carbs and plug up things again and again if you do not clean it all. Tank and lines included

 

[tawd77]

Re: 25hp 4stroke Yamaha idles but won't do anything else.

Where the throttle lever is on the carb, you will see a rod, with a rubber boot that should push down with the throttle - I think its an accelerator pump. Make sure the rud pushes down, when you give the carb some throttle.

In the bowl of the carb, there is a little round "pump" that this rod pushes. If the carb gets gummed up at all, this pump will get stuck in place, and all the engine will do is idle. There is a TINY phillips screw holding the pump assembly together. If you take the bowl off, the round metal disk should be all the way up against the phillips screw. If its not, the pump is jammed up with old gelled gas, and you will need to hose it with carb cleaner. Lightly tap on the disk until it pops back up into place. Be careful not to scratch the pumps cylinder area. Once it breaks free, work it up and down a bunch while adding carb cleaner, and it will free up, and the engine will then rev up.

 

[don25hp]

Re: 25hp 4stroke Yamaha idles but won't do anything else.

Thanks everyone for your response. After checking fuel pressure, and cleaning all fuel lines tank and carb agian I had, the same problem. I am glad to say I have discovered that the prime started assembly was bad(always up). It never got warm and expanded as it should. I took the needle apart and fabracated it the be all the way down all the time(no starter assit). Runs great!! I have a new very expensive starter assebly on order. Thanks again.