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2003 XP DI won't run past idle

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xpdiman

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Per the post title, my 2003 XP will not run past idle. The engine is fully rebuilt from the crank up as when I purchased it the engine had been flooded and sat for several years. I am not an amateur with the 951 engine having owned several of them over the last 20 years and done engine replacements and complete rebuilds. I have two identical 2003 XP DI units one of which runs perfectly which I have been using as a baseline and comparison unit when I suspect something is wrong. I believe my current issue is that the MPEM has the engine in some type of limp mode. When you connect the battery I hear the cut-off relay engage which I know from my working DI ski is not normal. The cut-off relay should only engage when the lanyard is attached to the DESS switch. According to the shop manual to test the cut-off relay it indicates you should first test the DESS switch by checking continuity between the black and black/purple wires from the switch. This should be "open" with the lanyard disconnected and "closed" with the lanyard connected. In my case it is "closed" whether the lanyard is connected or disconnected. The shop manual indicates to replace the DESS switch given my situation. My question is with the DESS switch bad and the cut-off relay engaging when it is not supposed to, could this cause the engine to die when you go past idle. To the best of my knowledge it is not throwing any error codes. I get the normal two beeps when connecting the lanyard and it starts just fine but again only runs at idle and dies when you try to accelerate. Hate to throw another $100 at the DESS switch if I have a bigger problem like the MPEM or something else. I would appreciate any feedback or similar previous experience with this type of problem. Thanks in advance!
 
I'd fix the DESS issue, you're gonna have to do that anyway before you can move forward. You may be getting voltage where you shouldn't as a result of the bad switch which could be confusing things. I suspect a TPI issue even though you are not getting a code. It's either not seeing the throttle open or not responding to it perhaps due to low pump pressure.
 
Why dont you just take the dess post off the good one and try? Same with the mpem. I have that same ski and they are a sob to work on like you said but I have found best to plug and play sometimes
 
I'd fix the DESS issue, you're gonna have to do that anyway before you can move forward. You may be getting voltage where you shouldn't as a result of the bad switch which could be confusing things. I suspect a TPI issue even though you are not getting a code. It's either not seeing the throttle open or not responding to it perhaps due to low pump pressure.
 
Thanks for the feedback! Pardon my ignorance but please define "TPI" (Throttle Position something I think). Also for the pump pressure are you referring to the fuel pump or the air pump? I did clean an test the fuel injectors while I was putting the engine back together but did not test the air injectors. I guess I am assuming these are OK or it would probably not idle like it does. I am going to move forward with replacing the DESS switch as a start...
 
Thanks! I had thought of this as well but it is not easy to swap out the DESS since three of the four wires feed through a wiring harness and into two different connectors. Thus to replace the DESS switch (which I think I am going to go ahead and do) I was planning to cut the wires to the connector and solder/shrink tube the new connections. I fear taking the MPEM out of my good ski and messing it up if something corrupted the ski which I am having trouble with...
 
I wouldn't cut and solder them since they are very sensitive to resistance and connection. For about $10 you can buy the tool for disconnecting the connectors.
 
I am loath to take a good ski apart to fix or test a broken one. :) Too easy to end up with to broken skis. LOL Then again... could b a pride thing or the hunt. Good Luck. !! :)
 
Miki do you have a part number or good description for the tool you are mentioning. I bought 4 packs of gadgets to open up wire connector and such. I lucked out and got a screwdriver type that works on the SeaDoo wires. Helped my repair the GTX right away.
 
Thanks for the feedback! Pardon my ignorance but please define "TPI" (Throttle Position something I think). Also for the pump pressure are you referring to the fuel pump or the air pump? I did clean an test the fuel injectors while I was putting the engine back together but did not test the air injectors. I guess I am assuming these are OK or it would probably not idle like it does. I am going to move forward with replacing the DESS switch as a start...

You know more than I do about the DI than I do but I got a lot of experience chasing fuel management issues and computer problems. :) I have 3 DI's outside I never started working on yet. My thought process is that when you open the throttle the engine kills. Generally means "not enough fuel." So... since the MPEM reads the "throttle position sensor" for fuel management that would just be the first place I would look. The pressure I am referring to is the fuel pump pressure. I found some awfully broken down filters in the tank on my first RFI. They obviously had never been replaced. I send my injectors off for reconditioning whenever I get an injected ski. I'm not chasing anything that I can't check. LOL Good Luck. Post up what you find. :D
 
That's the one I got. Just looked kinda dinky to me. :D Worked great though. Thanks Miki !!
 
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