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mhooker1
06-12-2010, 03:26 PM
Hey i am having a problem with my mcx 350 in my 04 x2. I can run the boat for about a half hour to an hour than it will randomly die. The boat will start back up and run again for a random period than shut off. I changed the fuel pump a year ago also had the ecu chip warrantied.

any tips?

Thrall
06-12-2010, 03:45 PM
First, bypass the tether kill switch to eliminate a glitch there. Mine will disconnect and kill the engine if I barely bump it.
You mentioned the ECM has already been replaced?
My '96 had a freak problem that I've yet too see happen to anyone else on here. The ECM was replaced once due to the prev owner's error in hooking the battery up backwards.
WHen I got it, it would die randomly, but the frequency increased with the ambient temp and increased heat soak of the engine.
Turned out the fuel pump driver in the ECM would short out when the engine got good and heat soaked. If this happens to be the case with yours, when it dies and you try to re-start, you won't hear the fuel pump prime up. If you do hear the fuel pump, then this isn't the problem.

mhooker1
06-12-2010, 06:32 PM
I can hear the fuel pump prime up when restarting. but could it be something with the ecm shorting out and killing the spark when the engine gets heat soaked?

Thrall
06-14-2010, 01:09 PM
I suppose it could be another function in the ECM that is shorting out like mine did with fuel, it's just that defective ECMs appear to be very rare. Before investigating that, I'd bypass the tether kill switch and see if it still happens.
If it's heat soak causing a circuit to open when it shouldn't, then the frequency should increase with the ambient temp and engine temp/heat in hte engine compartment.
Mine did, to the point where I knew about how long to shut it off, raise the cover and how long it would run to get it on the trailer.
If it really is random, I'd start looking at all your elect connections for something loose or corroded, including grounds.
I've had to tighten almost every screw and bolt on my 06 in the year I've had it, but the elect connections were all tight. Doesn't mean one may not be tight though.