Q: i have a 90cc adly atv and it is having problems starting and staying running. what can i do to fix it?

The ignition and fuel systems will have to be diagnosed. Make sure you are not using old (stored) gasoline. Old gasoline alone can account for hard starting and poor operation and, as well, will cause continuing problems due to the deposits and contaminants from oxidized fuel. Indeed, if the issue is old gasoline, the fuel system may have to be serviced (cleaned). There are many causes of hard starting, rough operation and stalling once started, but illustrative ones are a faulty engine coolant temperature switch (sensor), worn spark plugs, inadequate fuel delivery or pressure (clogged fuel filter), and contaminated or old gasoline. If you get the engine started, but it stalls, there could be a problem with the throttle system, idle air control valve if present, vacuum leaks, and so forth. Whether the vehicle does not start, starts and dies, or stalls, if you simply request a no/hard starting - engine diagnostic the responding certified mechanic will get this resolved for you promptly. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.