02 speedster stalls at 2500 rpm in water

[Thom]

Hello all,

I have a 240 hp fuel injected M-2 the problem is it runs fine out of water in water under load it stalls if I throttle past 2500 rpm. Fires right back up and will run all day under that rpm. I have checked fuel lines, filters, water passages, neutral safety switch and now am at a loss. I did read a previous thread with a similar problem but did not see a resolve. Any ideas?

thanks

 

[rookie101]

I already posted in your premium thread, but I'll add it here as well.



It sounds like you may have a problem with the low side of the fuel system. Your fuel system works like this.

The fuel is drawn from the tank by a low pressure electric lift pump which sends the fuel to an engine mounted mechanical pulse pump. From there it goes through the fuel/water separating filter, and then into the vapor separator through a needle valve controlled by a float. In the bottom of the vapor separator is a final filter attached to the bottom of a high pressure electric fuel pump that sends the fuel to the fuel rail and injectors.

If one of your low pressure fuel pumps is not working, the fuel/water separating filter is restricted, or the needle valve is sticking the vapor separator will not have enough fuel in it to keep the high pressure pump supplied when you are using lots of fuel at higher throttle settings.

You can just quickly check all your pressures on the low side. Electric lift pump 4-8 psi, engine driven pules pump 2-6 psi before and after the filter (you need to check this one with the engine running). Also if you take some tools with you, the next time it dies immediately shut the key off. Now look at the bottom of the vapor separator and you will see a drain plug. Put something under it and pull the plug to see if it is full of fuel (practice on land first so you know how much fuel should be present, and to avoid spills on the water).

You can check your fuel pump pressures on land, but wont get a good reading on the amount of fuel in the VS unless you can run it until it dies. There have been a lot of problems with the needle valve sticking, so you may want to order a new one from your dealer and just replace it if the pump pressures seem OK.

Aaron:cheers:

 

[Thom]

seadoo speedster dies at 2500 rpm in water

Hey Aaron, I had to bring the boat to a shop. They are perplexed. All the fuel pumps check out, ignition checks out has a new stator and regulators. It has NO gray fuel lines with the liners. They have contacted Mecury and are waiting for some more suggestions. They even checked the exhaust and thats all clear. He still feels its fuel related so any ideas from your end will be helpful. Oh and of course the ECU flashed no codes.

thank you

Thom

 

[rookie101]

How did they do their checks? If they did them on land with no load on the engine they're just kidding themselves. All the fuel pumps may work, but they may not have enough output under heavy load to keep up. You need to put a fuel pressure gauge on the high side and go for a water test. Make sure it does not drop below 32psi.

With the exhaust, how did they check it? They would either have to remove the rubber hoses completely to inspect them or, if they have an exhaust back pressure gauge, do a water test and make sure the pressure does not exceed about 1 1/2 to 2 psi.

Over the years, I've had a number of cars that will rum fine at idle, but as soon as you hit the highway or a good hill the fuel pressure will drop below the minimum specs. Only way to tell is to go for a good drive with a fuel pressure gauge stuck to the windshield.

Another thing to check (although I'm sure they have already) is to do a sweep of the TPS and make sure it does not go open after a certain throttle position. Other than that wiggle and shake all the wiring you can get at when it is running and make sure all the connections are good.

Make sure to let us know what they find.

Aaron:cheers: