mike in la

I just bought a used Challenger 2000 (year also 2000). When I start the engine a constant alarm sounds until you push the "FUEL WARNING SYSTEM" button beside the steering wheel. The guy I bought it from said it was a warning alarm for "FUEL WARNING SYSTEM", but after reading the manual it might mean engine overheating.
When I took the boat out today the alarm went off when I started it and then I pressed the FUEL WARNING SYSTEM button to stop the sound. About a half hour later the alarm went off again so I pressed the FUEL WARNING SYSTEM button again to stop the sound. WHen It was bring the boat in for the day I tied it up to the dock and turned the engine off. When i started it back up the alarm went off again but this time when I pressed the "FUEL WARNING SYSTEM" button the alarm continued????? Is a a gas or engine problem??
In the manual the FUEL WARNING SYSTEM button is suppose to beep but the sound I hear is a constant sound.
Thanks
Mike