07-15-2013, 06:06 AM #1
Engine shudders cuts off when warm
2003 msx 140 Low hour ski never in salt water.
I just got this ski, it had been sitting in a garage. The owner put a fuel pump in it last year.
It would not turn over so I put a new battery in it. Runs great until after about 20 minutes then engine shutters and cuts off.
Seems to do better at higher speeds and WOT but it can still surge like it wants to cut off.
After it cuts off it will start right back up.
I put a new TPS in it.
Replaced all gas.
Replaced plugs with proper ngk's.
Cut plastic on air cleaner cover and fixed the air temp sensor with Honda bond (silicone sealer).
I am starting to think it is the EMM.
If the EMM is getting warm and causing this I wonder if could I wrap a garbage bag around it and set a bag of ICE on it to keep it cooler for diagnostic purposes?
07-15-2013, 09:51 AM #2
- Join Date
- Jul 2007
- near Toronto, Canada
Did you ohm test the air temp sensor? Should be right around 1,000 ohms, give or take.
Ice wrap on the EMM sounds like an interesting idea.
Have you confirmed proper water flow through the EMM and out the exit hose at the rear?
07-15-2013, 12:16 PM #3
I well test that.
I did not check water flow threw the emm, just blow it with compressed air?
I was thinking dry ice might be better, that way there is not a chance of melting water getting into the connectors.
07-15-2013, 01:13 PM #4
- Join Date
- Jul 2007
- near Toronto, Canada
The electrical connectors on the EMM are all supposed to be water sealed type. Normally each connector has a thin rubber gasket on the plug with a thin film of dielectric grease as a lubricant.
Air temp sensor is mounted (annoyingly) to the bottom surface of the flame arrestor base. Same part that gets cut by the web from the plastic flame arrestor cover.
07-20-2013, 05:26 PM #5
Was Able to Blow through the hose that runs from the front of the motor through the EMM with air. Also checked the bigger hoses that run water through the motor. They were clear. The Air Temp sensor Ohms out at 975.
Next step ICE BAG!!!!!!!
Last edited by the bull; 07-20-2013 at 09:17 PM.
07-21-2013, 10:59 AM #6
Ok, so I went out this morning with a bag of ice right on top of the EMM. It is kind of hard to get it completely covered but I did the best I could. It ran for about 30 min and would only bog and shut down a little. I pulled the EMM loose from the styrofoam and put the ice under it, it never cut off and would only have a light surge. I put ice on the top and on the bottom of the EMM and it ran like a champ for 30 more minutes. It never surged or cut off at all when it was surrounded by ice.
I think the EMM is getting too hot or there is a bad solder joint on the board. I want to figure out a way to cool it down. Maybe a fan or a inline cooler placed before the water inlet to the EMM. Is the water coming out of the front of the engine already warm or should it be cool?
I guess if need be I could get the EMM repaired. I hope they test them hot when they are fixing these.
Last edited by the bull; 07-21-2013 at 03:06 PM.
07-21-2013, 09:42 PM #7
I noticed something........
The water line that cools the EMM is coming from the front of the oil pump from a small brass outlet. There are 2 of these on the front of the pump. One one the top and one on the bottom. Mine is routed to the EMM from the top one. The bottom one goes to a bigger flow hose at the back of the ski. In the service manual the bottom one is going to the EMM. Is mine routed wrong? does it matter if these are flipped? What goes on inside that oil pump where those fittings go?
Last edited by the bull; 07-22-2013 at 06:55 AM.
07-22-2013, 10:14 AM #8
07-22-2013, 11:46 AM #9
Your routing is correct, the diagram is wrong. You want the exit to be higher so the air does not get trapped and cause a loss of cooling.
The picture of the processor is normal, even on an EMM that has never overheated.
07-22-2013, 09:20 PM #10
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