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Discussion Starter #1 (Edited)
I have a 1996 SLX 780 that I bought from my neighbor. Last season he said he was having problems with it throttling up to full throttle. After messing with it, I found that it will rev to 6700ish rpm on the trailer with a garden hose hooked to it, but when placed in water, it is limited to 4300rpm. I have replaced all the fuel lines, replaced the fuel/water separator, bypassed the the fuel shut-off, rebuilt the fuel pump, rebuilt the carburetors, new spark plugs, battery and replaced the CDI box. The unit starts and idles with no problem. It is just doggy getting up to 4300 rpm, and then it seems there is a rev limiter that kicks in. The MFD works fine and displays the fuel and oil levels appropriately. There are no other warnings that are displayed.

Could it be the low fuel/oil heat switch in the electrical box? Not really sure where to go with this anymore and don't want to replace parts if not necessary. :confused:
 

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Seems like your doing a lot of work so there must only be a few other problems. Check the head gaskets and make sure theyre in good condition. Mine were cracked and allowed water on the piston. While your at it check the piston heads for any holes. If everything there is good then check the compression on the cylinders. I dont know the exact numbers but if its lower than 100 on any of them you have a problem. If the head gaskets are cracked replace them dennis kirk has a great gasket package for 55 bucks.
 

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780 rev limited

i bought a 96 slx 780 a month ago with a very simular headache. three things that can put your machine into limp mode. low fuel, low oil, and overheating. for me it was a fuel sending unit saying it was out of gas. the engine would only run 4150 rpms on the water. although it had a flashing red light as an alert for low fuel, so i jumped the two wires coming out of fuel sending unit to trick it into thinking it had a full tank all the time. runs good now but i have no gas gauge, aleast for now.
 

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What do you mean "jumped the two wires"? I'm new to watercraft repairs but have worked on bigger engines (cars and trucks) I'm not familiar with this term however...Help?
 

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I think - simply put - he wired the 2 wires together thereby completing a wiring circuit - now his fuel sending unit has a completed circuit just like it would have when the gas tank is full.
 

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don't start it with a fuel leak! traped gas vapors in the engine compartment = kaboom
I have seen this on the water. You could find it on youtube also. Find the leak or replace the tank. It's cheaper than a new hull
 
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