Hi all,

I'm having a problem starting the engine on my kid's ATV which is a Tao Motor NEWCHEETAH (125cc 8" upgraded version):
- owner's manual - https://taomotor.com/wp-content/uplo...ual-6-4-21.pdf
- product page - https://taomotor.com/products/atvs/newcheetah/
The engine cranks but doesn't start, not even a sign of firing up (no intermittent starts at all).
The ATV was purchased less than a year ago on July 2021 and was used for only 2.0 hours according to the built-in engine hour meter (within the engine break-in guidelines).

Last time, the ATV was used about a month ago without any issues. I'm not sure if the engine was shutdown via engine valve "OFF" or the red "killswitch" button on the handle. However, the carburetor definitely had some fuel left in the bowl before I drained it during my troubleshooting.

The ATV was stored inside the garage with the outside temperature never below 32F (Florida).

Will appreciate any advice on next steps I should do


The following troubleshooting steps were done (outside air temperature 80-85F, dry air):

1) checked the fuel tank - almost half the tank of 93 fuel (no water, debris, normal color and smell), the fuel cap's vent is unobstructed;

2) the fuel delivery system to carb:
- no leakage,
- the black rubber lines aren't porous, obstructed, or pinched,
- the small transparent barrel fuel filter is installed correctly,
- on/off fuel shut-off valve is working as intended (ON = fuel flows, OFF = fuel doesn't flow),
- if I unplug the fuel line from carb with fuel shut-off valve ON, the fuel flow diameter is about the same as of the tubing;

3) battery is fully charged and maintains normal voltage with minimal sag under load when the electric starter is engaged, fuse is good;

4) verified all safety features are disengaged for engine start, including:
- remote control (made sure to push unlock button),
- red "killswitch" handle button (is set to "O"),
- both front (with front parking brake engaged) and rear (foot) brakes are held all the way down during cranking,
- engine stop lanyard (red cap) is seated in its spot completely;
5) fuel valve is ON;

6) transmission set to neutral ("N" is illuminated on the instrument cluster);

7) ignition switch key ON;

8) tried playing with throttle lever while cranking the engine - no luck (increase in cranking rpm is audible when the throttle lever is pushed);

9) oil level is checked (almost max);

10) air filter (foam element) is clean of dust/debris and oiled;

11) engine:
- no weird noises,
- great compression,
- no cracks in the gaskets (exhaust too),
- replaced the stock no-name spark plug with a brand-new NGK CR7HSA (4549) spark plug,
- when spark plug is very close to the engine, the spark is firing with no issues,
- engine cranks fine and fast, unfortunately, will not start no matter what,
- tried spraying air/fuel mix directly into the spark plug hole, putting spark plug back in, and then cranking without results;

12) carburetor:
- tried both choke lever ON (horizontal) and OFF (down);
- drained the carb bowl of any fuel left,
- tried blowing the fuel into the carburetor directly via fuel line - no luck,
- for some reason, the carb will not let in the fuel at all when trying to crank the engine (is it vapor/air lock?),
- visual inspection did not reveal any damaged components.

 

Remove the carb and then remove and clean the jets, blowing both them and the holes they came from out with compressed air. Refit carb and see if it starts. If it still won't, check valve clearances. If they are OK, check compression, you need a number (above 80psi) to be sure it is OK. Check the piston really is at TDC when the timing mark on flywheel says it is, if it isn't, the flywheel has slipped and this throws ignition timing out.

 

merryman, thank you for the advice - I will do as you said and will report right back!