2015 MSU-500 crank - no start

[Ben1098]

HS800.....should be HS500.  See Motorcycle Doctor store....has several units for the HiSun 500. 

While you are talking, confirm the flywheel P/N also.

Talk about going 20 steps backwards...............been there as we usually ended up with the dogs after $$$$$$$$$$$$$$$$ wasted and they did NOT usually get the "good" parts back as there are no returns on electrical.  My personal  best was a Honda 350 ATV.  Dead IGNITION.  3 H shops, 1 Independent.  Shotgun parts.  Had thick folder.  From Chicago area.  Drove down and stood in line a busy (pulled up front) Sat AM.  Seen ALL parts for the IGN replaced shop WO parts list.  Clue:  Asked what he used it for.  IDNR food plots. OH!  Took clip lead and meter to his PU.  T/S in the bed......first guess at the sales counter was right.   Run.  Boss didn't even know I left.  He was charged for 7 minutes.

MY take on the whole story...............exhaust cam wear and low compression was the initial killer.       CHOW.....hope you finally win.  BEN

[Prepper]

UPDATE:  Got the new ECU today.   Installed it and the engine fired right up !  Success... but it will only idle for about 30-45 seconds, then dies like someone cut the power.  Cycle the key and it fires right back up, and I'm talking immediately.   Runs another 30-45 seconds, then dies again.  Plenty of fuel pressure, will test again tomorrow to get actual numbers.  Right now I'm thinking Idle Air Control.  I'll remove that tomorrow and check it out.  I have no idea how long the machine has been sitting without running.  Good news is though, the engine sounds strong when it is running.  I'll report back on any progress.

[Ben1098]

Quick test.  Sounds like the fuel pump is not keeping up with demand.  After the 30 sec or so run time, and starts to die,  give it a wiff of starter fluid and see if it recovers........fuel starved.

Key OFF wait 5 sec or so....Key  ON only------no start position.  The fuel pump is turned on for about 5 sec to PRIME/PRESSURIZE fuel rail.....signal is from the ECM.......wait it out for time out......then start.     Listen for the short prime time running.  Start.....ECM should now keep the fuel pump full time.

Put a test light on the pump connector (clamp to Gnd) and check for 12v.  Then reverse the clamp connector from Ground to a hot +12v.....you can now check for a good ground at the connector.

[Prepper]

9 hours ago, Ben1098 said:

Quick test.  Sounds like the fuel pump is not keeping up with demand.  After the 30 sec or so run time, and starts to die,  give it a wiff of starter fluid and see if it recovers........fuel starved.

Key OFF wait 5 sec or so....Key  ON only------no start position.  The fuel pump is turned on for about 5 sec to PRIME/PRESSURIZE fuel rail.....signal is from the ECM.......wait it out for time out......then start.     Listen for the short prime time running.  Start.....ECM should now keep the fuel pump full time.

Put a test light on the pump connector (clamp to Gnd) and check for 12v.  Then reverse the clamp connector from Ground to a hot +12v.....you can now check for a good ground at the connector.

Well, it appears all it needed was some time.  After several attempts, it started to idle just fine.  After reassuring myself that it appeared to be running well, I took it out on the road for some "run" time.  It was sluggish to get rolling (like the belt wasn't gripping) but after a few miles it got much better.   I think it had been sitting for quite a while and things just needed to break in a little.  After several miles both the engine and drive train seems to function normally (at least what I would expect).

The only thing that concerns me at this point is the high-end engine RPM.  Does anyone know what kind of max- RPM's I could/should expect from the engine?  Right now it seems to start bogging down in the over 4k range (sometimes it will get to 4200).  Not sure where the ECM starts clipping the RPM's at.  The ECM I purchased at Motorcycle Doctor was the "enhanced tune" unit that is supposed to allow for another 500-RPM's.  Is 4k all I can expect from the engine ?  Additionally, occasionally, the engine hesitates a little from a complete stop, but quickly picks up and takes off.  That may work itself out with some more miles on it. 

But all in all... things are looking promising at this point.  It appears the ECM (the WRONG ECM) was the main issue from the beginning.  I suspect when the original owner bought the new ECM, and that didn't work to get the engine running again... he threw his hands up and quit.  Little did he know that either he ordered the wrong ECM, or, the company simply pulled and shipped the wrong one. 

[Alien10]

Hey UTV Board stie Admins:

The board  needs to award Ben1098  the UTV Board "Medal of Honor".  !!

👍👍👍  

[Joe Breaux]

Ii agree..that's some great help he provided.