900zxi wont rev over 4500 in or out of the water?? - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts

pistonslap · 07-10-2011, 06:26 PM

dose anyone have any ideas why my 97 900 zxi wont rev over 4500rpm weather it is in or out of the water? its really snappy but it just caps at 4500?
i just put a new engine in off of E-bay it may be from an stx but I'm not sure, if that make a difference.

ggauvin · 07-12-2011, 09:57 AM

Might be the over-temp switch. If this switch fails, then the e-box thinks you're over-temp. Then it limits revs to about 4000, so you can limp home without too much additional heat-up. This switch is in the hose path leading to the pisser. I forget whether it is normally open, or normally closed.... I think you unplug the connector to ignore it.

Scaf77 · 07-12-2011, 01:10 PM

I had this same problem with my 750 zxi. It was the oil temp control unit. I unplugged it and it reved up

ggauvin · 07-12-2011, 02:16 PM

I didn't know these skis had oil temp control units. Are you sure it wasn't the water over-temp sensor / switch in the bypass (pisser) hose? Some have a low oil level sensor switch but that would shut down your engine completely. Most have some kind of indicator lite for water temp overheat, but in the bright sunlight these indicators can be very hard to see.

Scaf77 · 07-12-2011, 07:11 PM

Quote:

Originally Posted by ggauvin

I didn't know these skis had oil temp control units. Are you sure it wasn't the water over-temp sensor / switch in the bypass (pisser) hose? Some have a low oil level sensor switch but that would shut down your engine completely. Most have some kind of indicator lite for water temp overheat, but in the bright sunlight these indicators can be very hard to see.

I didn't think so ether which is why my ski was down so long.
Its a little black box about the size of a pack of smokes mounted under the cowl, The book calls it oil temp control unit, Babbits online just calls it control unit.