yamaha stops running

I have a 96 wvt700 and it runs great for 20 minutes, then it doesn't go above 10 mph. It fells like the rev limiter is restricting the performance. This happens quite consistently. 20 minutes and I'm putting back to the dock. I've changed the fuel filter and also did a test run with the thermocouple removed from the block. It did not help. Please give suggestions on what to troubleshoot next. Thanks in advance.

ebird99

Re: yamaha stops running

check the core wires in the spark plug leads, had that same problem once and it took me a long time to track it down to bad wires inside the spark plug leads.

Re: yamaha stops running

I ran the resistance checks on the CDI and on the ignition coil, everything checked out ok. The yamaha mechanic says that the ignition coil could fail once it heats up. Is this possible?

Re: yamaha stops running

I would check the fuel supply first but a coil could fail like he is saying, there are small lights that go on the plugs and hook to the ignition wires to the spark plugs where you can actually see the spark firing as you ride with the seat off, these cost about 5 dollars each, if you really suspect bad ignition you could place these on the plugs and watch the spark if it gets weak when the problem occurs you will know the spark is the issue,, but it is usually a problem with fuel, to check that , once the ski starts to loose power, back off the throttle for a few seconds and then give it throttle and see if it tries to run batter for a second and then boggs down again, if this is the case you are starving for gas.

Re: yamaha stops running

I check the fuel hoses for kinks, also checked the vent line for flow, everything was ok. I put in a new set of plugs and cleaned the connectors. Also disconnected the thermosenser wiring. It ran all day with no problems. I also found a cracked oil cap socket ( the thing the cap screws into). I wonder if water in the oil tank was giving me problems. I ordered a new one.

Re: yamaha stops running

re conect the heat sensor and see if it happens again, if so replace it

Re: yamaha stops running

I did reconnect. I also tapped in a "quick disconnect" that I ran to the fuse compartment. That way I can troubleshoot on the water. I'll retest tomorrow. Thanks for the input Jeff