Steve wrote:

Now I'm having problems with false alarms from the fuel vapor detector.

The things will detect nearly any hydrocarbon and are sensitive to
moisture if mounted low in the bilge.

Your engine probably vents crankcase fumes and diesel vapors into the
engine compartment ... the time delay sounds about right for the engine
to heat up and start "fuming" as well as increasing the local humidity.

Can you adjust the sensitivity or relocate the sensor?

Rick