Fuel Delivery Problem?

[keithet]

I have a 2001 40 hp 4 stroke Yamaha with very little hours on it. It starts easily and it idles very nicely at about 850 rpm. It runs good until I get the rpm's up to about 3500 and after a minute or two, it starts to hesitate and unless I back off it quits like it's starved for gas. It restarts in a few minutes and runs very well at lower rpm (1500-2300 rpm's). The gas is fresh and it happened last year at the end of the season with different gas.

I changed the fuel filter and that didn't help. I tried it with a portable tank with a squeeze bulb and tried it with a new bulb and hose with a built in tank. My next move, on the advice of a Yamaha dealer is to run it again and when it starts to crap out to have a friend squeeze the bulb (human fuel pump I guess ) and see if that makes the hesitation go away. Any other ideas? I assume if the "squeeze the bulb by human" works I am looking at a bad fuel pump??

Thanks for any advice you can give me.

 

[tuskvt]

Re: Fuel Delivery Problem?

Hi-

I'm curious if you have any success with this? I seem to be having a very similar problem with my Suzuki 225hp 2-cycle engine. I just put my boat in for the season and it starts with no problem and it idles fine and runs at low speed with no problem when it is still cool, but when I try to go fast (especially when the the engine is warm) the RPMs go up and down and it will usually die unless I move it back to idle. After the engine is has been running for 30 minutes or so it doesn't even run well at low speed - rpms go up and down and eventually it sputters and dies.

I have tried squeezing the bulb while experiencing the problems and it doesn't seem to make any significant improvements. I have also replaced the fuel filter.

It looks like there is a a small off-white plastic filter on the fule line within the engine - is it possible that needs to be cleaned? It looks to be difficult to reach and unscrew, though.

Other posts seem to point to fuel pump, carberator or injector problems. I have electronic fuel injection, so that means I have no carbuerator, right?

Does anyone know of any fuel additives that may help?

My next step is going to be to call the marina, but I'm still hoping I can find a simple low cost solution (though I realize that's not likely).

Any suggestions would be appreciated!

-Scott