Hello and thanks in advance for any help. I have a 2015 Kymco MXU450i ATV I cannot get running. I ran it out of gas about a month ago and I have struggled with it ever since. My local dealer has a 10 month wait to fix these so I am trying to do it myself.
Symptoms:
I can start is up by feathering the throttle and it will not run on its own, or idle. I can keep it running by pumping the throttle, but only for awhile. Eventually it backfires and will quit. No codes on the control panel, no trouble engine lights, nothing.
Course of action:
Initial I thought I had just picked up trash in the tank, as the tank was rusted. So I started by pulling the tank, and cleaning, sealing it. Tank now looks like new. I then replaced the fuel filter sock and was not reading appropriate Fuel pressure. Next I replaced the fuel pump with one from Quantum Fuel Systems, and all the rubber fuel hoses. I now get 45 PSI fuel pressure when I test it with a gauge, and it will hold pressure constantly, and not leak off.
It still would not run so I pulled the injector and cleaned it. I have NOT replaced the injector because it looked in good shape (again my local dealer is quoting lots of $ and a long wait to get an injector). I cleaned it intensely and can get a good pulsing fuel spray out of it now. So, I figured the fuel system cannot be the issue any longer.
I moved on to the MAP sensor, because I could get one, and replaced it with a new one. Still would not run.
Next up TPS. I have tried the TPS reset (I can find 2 different procedures online and tried both many times: 1) hold the throttle in while turning key on for 8 seconds, and 2) keep it running by bumping the throttle til it reached operating temperature, although this one seems to be a procedure for a scooter not an ATV, I tried anyways). Nothing worked. I was able to get a TPS sensor and installed it, brand new, and tired again all reset procedures I could find. Still not running.
At this point I am out of ideas, so I am grasping. I pulled the spark arrestor out, and also have had the entire intake and exhaust system out, no change. I have changed the spark plug, and also tested compression, which is good. Have NOT messed with valve lash.
I don't know what else to try, and again, cannot find someone to work on it. I do not really want to spend money on a new throttle body and ECU, but is that next?
I can post a video of how it runs if helpful.
