2004 40hp fuel system problem??

[Sailorkj]

I have a 04 40hp two stroke that has been sitting for 2 seasons. I rebuilt the carbs and the motor will start and idle just fine BUT I can not get enough power to plane off. It seems to run fine at low speeds but will not accelerate under load enough to plane my 16ft skiff. I can rev the engine with the throttle but not under load. I suspect the fuel pump may be the problem but my mechanic thinks not stating that when the pump goes it usually will not run at all. Any Ideas????

Thanks

Ken

 

[robert graham]

Re: 2004 40hp fuel system problem??

Well, the fuel pump is easy enough to check and/or replace, but if that's not the problem then your carbs may have a plugged jet. Maybe drain your carbs float chambers onto a clean white rag to get an idea if water or debris is in there. Good Luck!

 

[Sailorkj]

Re: 2004 40hp fuel system problem??

Well, the fuel pump is easy enough to check and/or replace, but if that's not the problem then your carbs may have a plugged jet. Maybe drain your carbs float chambers onto a clean white rag to get an idea if water or debris is in there. Good Luck!

Carbs have a fresh rebuild, yesterday, and did have 2 plugged jets. They are clean and fresh now which leads me to believe that there must be another issue.

I am in Greenwood SC by the way... I see you are in Greenville.

KJ

 

[99yam40]

Re: 2004 40hp fuel system problem??

Check compression just to be sure all cylinders are sealing well.
Test fuel pressure/vacuum and check to see if pump has leak in diaphragm

Usually if the motor will not run under lead the carbs need more attention running lean
Anything that was in lines or pump will end up in carbs when fires back up after cleaning, check to see

And flush the lines and pump into a clear container and see if anything comes out.

Did you do the link and sync like service manual says when carbs were reinstalled?