Coleman/Hisun 550

[Bret4207]

More issues with the 2019 Coleman 550. It stopped running again. Long story/short, I checked valves, injector (replaced) plug (replaced 2x with new NGK)  checked fuel flow , it eventually started. Ran great for a while, 10 minutes or so. Then it started the spitting and sputtering and not wanting to rev up. When first started it would rev freely (no load) to 6-7K, which was as high as I felt comfortable. Wouldn't go past 4500-5k under load on the road. It gets going and then it cuts out. The drivers seat belt is buckled. The previous time I still had it under warranty, I eventually got it to a shop that removed the in-line fuel filter that had been added and then it ran good. My thought is that the fuel pump may be weak. The other possibility that occurs to me is the cut out/retarder for the seatbelt is malfunctioning.

I purchased a CD of the shop manual, but it appears to be for an older model with a carb and not the EFI.

Open to hearing thoughts and opinions and which way to proceed. I'm planning on replacing fuel pump and fuel line and getting a (hopefully) better quality injector. I would appreciate any sources (Motorcycle Dr???) for better quality components.

I have also been told by a person claiming to be a Hisun tech in a southwestern state that the way to "set" the machines CPU/Brain/whatever you call it, is to hold the gas pedal to floor let it get to it's highest RPM and then shut off ignition. I'm assuming one does this ASAP. Does this sound even remotely correct? I picture a blown engine myself, but I'm an old guy, so...

[Bret4207]

An update- I pulled the box off so I could access stuff. Checked the valves, both appeared to be at the recommended clearance, forget what that was. Then pulled the injector and checked for fuel spray, got it. Then pulled injector off the fuel line and checked the flow, got lotsa gas fast, no idea on fuel pressure though. Checked spark again and with another new plug- good blue spark. I tried giving it a sniff of ether through the injector hole and she fired. did that a couple times and she certainly seemed to want to run. So I put everything back and gave it a try. She spun and spun and suddenly sounded like she wanted to start, so I kept going and it did! I ran it around for 15-20 minutes and got her well warmed up. I still had that thing where it would get to about 5 or 5500 rpm unload and it would die. It would run up to the 6-7K area with no load (in neutral). I was thinking the fuel pump may be weak or the filter on the pump might be clogged a bit. Got looking around and found "The Motorcycle Doctor"s website. There I found the instructions on how to reset the ECU and injection system. That was "Clean the O2 sensor first and then warm it up good, run the engine up to full throttle for 5 seconds and shut it off at full throttle, wait 15 seconds and restart and drive it around at varying speeds and loads"  according to the instructions.  I did that and after some spitting and sputtering I was able to run down the road in excess of 40 mph at about 6500 rpm, which I haven't been able to do since it was new! I still get the bogging, like it's either triggering the retarder in the seatbelt system or maybe running out of fuel. I still wonder about the fuel pump. I don't the gauge and fittings to check it.

 

At this point I'm further ahead than I have been for some time. I'll update as I work on it.

[Mark A]

Video i watched from a dealer of new units had to unplug the fuel pressure sensor closest to the head , plug faces down .....this allowed my used 500 coleman to start and idles when nothing else would ?

[Bret4207]

Since I last posted I figured out the O2 sensor seemed to be bad, but the decompression system on the camshaft let go and shot pieces out through the cover! Waiting for space in the garage so I can fish all the metal trash out and put in a new cam and parts.