Help.. Power problem polaris 94 sl 650

[jspring0033]

Ok pro's,

I need some help, I have a 1994 polaris sl 650 that originally had a charging problem with and have since changed out the regulator recitfier and it starts up no problem whatsoever... but here is my next problem, when i get the ski out on the water it runs great for a while maybe 20 - 30 min then it starts acting up like its losing power, enginewill run at full throttle or what i think is full throttle but run maybe 5 mph across the water and then it will pick up speed but not full speed and act like its not getting enough fuel maybe or something is clogged in the impeller, the sound is like its not getting enough fuel or water through the impeller, im not sure which.. maybe yall could provide some insite into what i should look for or maybe the same has happend to you.. HELP if you can please thanks so much!

[xlint89]

Welcome to the Hulk.

Have you done a compression test?

Have you checked the cooling hoses for obstructions?

How soft is the exhaust hose going from the waterbox to the hull exit?

Have you checked the fuel filters? Or rebuilt the carbs?

Have you replaced the fuel pump?

[jspring0033]

No I havent done any of the above, Im new to owning a ski and im just learning as i go, my specialty is motorcycles but kinda the same concept in a way..

i will start at the top of your list and see where it takes me, thanks for your help!

what do you think off the top of your head would cause it to run fine for 30 or so min then run like ****, ive been on the water twice now and same issure??

[seaobin]

is there a vacuum break on the gas tank?

if always 30 min:
1) heat related, fuel or electrical
2) vacuum related

[K447]

Welcome to the Hulk!

If you have not done so already, download the 1992-1998 Service Manual.

Next time this happens, stop the engine, then crack open the gas cap, and observe whether there is vacuum or pressure released. Close the cap, then try riding it again right away, see if the problem is temporarily fixed.

Under normal operation, the fuel tank builds modest positive pressure. If the vent valves are stuck closed, it can develop a vacuum inside as the fuel is consumed, causing the fuel pump to be unable to move enough fuel to the carbs.

Too clarify, you are observing a surging drop in engine RPM when the problem happens, not a high revving of the engine without thrust - correct?

[jspring0033]

Welcome to the Hulk!

If you have not done so already, download the 1992-1998 Service Manual.

Next time this happens, stop the engine, then crack open the gas cap, and observe whether there is vacuum or pressure released. Close the cap, then try riding it again right away, see if the problem is temporarily fixed.

Under normal operation, the fuel tank builds modest positive pressure. If the vent valves are stuck closed, it can develop a vacuum inside as the fuel is consumed, causing the fuel pump to be unable to move enough fuel to the carbs.

Too clarify, you are observing a surging drop in engine RPM when the problem happens, not a high revving of the engine without thrust - correct?

Yes thats correct, its like its wanting more fuel and ever so often its seems like fuel will get though and pick up speed for 1 or 2 seconds and rpms then go back to running sluggish..

[jspring0033]

ok, problem in the first picture i have 2 hoses that lead from the top right of the picture to nothing they just hang but they have connectors that might lead me to believe they connect to something, any suggestions?


2nd pic.... to the top left the little black vent right above the rectangle sticker, i know that is some kind of vent also but it leads to the back of the engine but isnt connected to anything but it has a zip tie around the end of the hose leading me to believe that it connects to something... any sugggestions please?

[jspring0033]

?

[starflight]

ok, problem in the first picture i have 2 hoses that lead from the top right of the picture to nothing they just hang but they have connectors that might lead me to believe they connect to something, any suggestions?

They are for the bilge siphons. They should have screens on the ends laying in the hull. Make sure they are un-obstructed. They automatically drain the hull when running.


2nd pic.... to the top left the little black vent right above the rectangle sticker, i know that is some kind of vent also but it leads to the back of the engine but isnt connected to anything but it has a zip tie around the end of the hose leading me to believe that it connects to something... any sugggestions please?

Its the vent outlet for your battery. Connect it to the vent port on the battery.

[Neal Van]

Change that crappy fuel pump with a triple