AdamG

So I figured out why I could only go 10-12 mph in forward. I called "Motorcycle Doctor" out of Missouri and a guy named Craig is an expert when it comes to Hisun anything. They also sell Hisun parts. Once I told him what was going on, he immediately said he knew exactly what the problem was. It is the reverse rev limiter. He said cut the wire at the ECU and it will fix it. I explained that it was not a problem in reverse or a revving issue, it just would not go over 10 mph. He said it did not matter, forward or reverse, for some reason Hisun ECU's do not know what gear you are in (FWD or REV) and will limit your speed in forward or reverse. I cut the wire he told me to cut and sure enough, no more speed limiter! It does about 30mph with me on it. It also runs about 9,000 rpms. I did not think they spun that fast! I uploaded the document that Craig sent me explaining what wire to cut. I think this is just for the machines with the 2 plug Delphi ECU's. In the document it says that it is a blue and green wire but mine was a green and white wire. I confirmed via the service manual that I was cutting the correct wire. Hopefully this helps someone else who runs into the same problem.

SUCCESS!!! Finally figured out the problem. The plug that connects the pickup coil to the shielded wire to the ECU was bad. Soldered the wires together and starts and runs good; under 10mph... Lesson learned: check the voltage all the way to the ECU. I took the ATV for its maiden voyage and it was only able to get up to 10-12 mph before cutting out. Once under 10mph it kicks right back in. It is not specific to the RPM's either. Also I can fly in reverse but that is a little scary. Is there some sort of safety device on the ATV that limits the forward speed to 10mph?

@Ben1098 Thanks again for the info. I just did another test and I think I confirmed the shielded wire is bad. I hooked up my DVM directly to the pick up coil out of the crank case housing and got 3.9 volts AC when cranking the engine over. I plugged the pick up coil back to the shielded wire, cranked the motor and tested voltage at the ECU plug and got 0 voltage (no signal going into the ECU). I am going to try and find some shielded wire and make the soldered connections as you suggested. I will report back to let you know if that fixed the problem.

I did. I just checked the message and I sent you the correct number. Not sure what is going on.

It was on the ATV when I tested it. I tested the old one (from when it was running) and it is 116 OHMS when it was off the ATV.

@Ben1098 Thanks for the reply. I unplugged the shielded wires from the ECM and pick up coil (completely isolated) and tested each shielded wire individually and they both have 0 resistance. It just does not make sense why the difference in resistance when it is plugged into the pick up coil yet there is no resistance when it is unplugged.

I did some testing last night and got some "weird" readings. I tested the pickup coil from 2 different places; directly from the plug (got 119ohms) and at the end of the wiring harness that goes into the Delphi ECU. The 2 pickup wires that go to the ECU are shielded with a grey exterior and foil looking interior (assuming for more insulation) When I tested the resistance just before the ECU (where the pick up wire go into the ECU) I was getting anywhere from 8-10 milliOHMs. I was assuming I should have the same resistance when checking just before the ECU but the resistance was drastically reduced. I then tested the resistance of the shielded pick up wires and there is no resistance at all. Not sure if this all makes sense and you are tracking with me. I can take pics to better explain if needed. Not sure if this is a red flag or normal. Thoughts?

Thanks for the replies @Savage3 and @Ben1098. I checked everything and the only thing out of spec is the pickup coil. I am getting a reading of 119 OHMs when the specs say it should be 459-561. The problem is that it is brand new. I also tested the old one (the one that was on when it was running) and it has virtually the same resistance (116 OHMs). AC voltage coming out of the pickup coil at cranking speeds without the spark plug in is 3.5 volts. Not sure what it is supposed to be. Could a bad rectifier cause a no spark/injector pulse issue? I am at a complete loss. I live in the Dallas, Texas area. I would be willing to pay someone to diagnose.

View File 2015 Hisun Axis/Forge 110cc Service Manual This is the Service Manual for a 2015 Hisun Axis/Forge 110 ATV. It may include other years. Submitter AdamG Submitted 06/04/2021 Category Hisun  

I have a 2015 (EFI) Hisun Forge 110 atv that has no spark or injector pulse. I have replaced the Stator/pickup coil and ECU and still can not get anything. I have brought it to 3 different Hisun Service centers and no one can figure it out. The last service center said they can get a very "weak" spark but that is about it. I consider myself pretty knowledgeable about engines but this one has me (and 3 Hisun service centers) stumped. I just uploaded the service manual for this machine. Any help or advise that you can give is going to be much appreciated! 110 ATV Service Manual.pdf