Your unit coming on and turning off usually points to a water pressure or flow issue. This is due to either low or high water pressure or flow. The L5, L7, and L10 all require between 20-80 PSI. Now the tricky part comes with water flow,even though you may have to correct the PSI it does not always mean you have the correct water flow.
Water flow pertains to GPM (gallons per minute). In reference to the L5, you will need no less than .75 GPM and no more than 2 GPM for the unit to operate properly. The L7 is rated for 1.6 GPM, so the unit will require no more than 2.3 GPM to run efficiently. As for the L10, this unit is significantly larger and is rated for 2.5 GPM. It will also require at least .75 GPM for the unit to operate and no more than 4 GPM to function properly.
If you are trying to operate one of these units with low water pressure please follow the directions in the link posted below.