Got my boat out of storage and after connecting the batteries, the gas fume detector in the bilge keeps sounding. I checked everything out and there is no gas leak and the alarm sounds even when the hatch is fully open.

I may have sprayed the sensor and got it wet with Simple Green while I was cleaning up after winterizing last fall.

Could this have fouled the sensor?

yes,,unhook the sensor and see if the buzzard goes off or try smacking the sensor,,could have crud in it..

blow it off with air, however best bet may be to buy new.

mine kept going off, turned out I had a exhaust header gasket starting to leak.

the gas detector picked it up before I could even hear it.