Mercury 150 hp Pro XS 2026

by Tom Pile
(Boston, Ma. USA)

Within a few minutes of running the unit it alarms go off. At first the alarm was intermittent and occured twice during its maiden voyage of about 45 minutes duration. Next time out, intermittent alarm about 5 minutes after running up on plane at 3000 rpm then ran off and on while fishing for the rest of the day without alarms. Third time out, constant alarm immediately upon trying to get up on plane and went into guardian mode. Took it to the dealer and he hooked up to his computer. He said my battery terminal nuts were loose and I cannot run the 4 blade Mercury Spifire 21" pitch prop that I have been running for 10 years on my old 2004 Xr6 because the prop would deform under the torque of the Pro XS and cause an over-rev condition.
I will tell you that the nuts were tight because the first time I experience the intermittent alarm I searched and saw where loose battery cables could cause this so I immediately tightened the nuts although they were already sufficiently tight. I also checked the oil level which was fine.
Okay, nuts tight and installed a s.s. 23"pitch Tempest prop that originally came on my XR6. Immediately upon operation the constant alarm sounded and Guardian mode activated. Shut down, waited a bit and started again. Same thing, immediate alarm a guardian activation.
4.6 hours total on the motor at this point and dealer is scratching his head and, supposedly, consulting with Mercury.
After 21 years of good service from my old XR6, I thought I'd invest in a more modern and more dependable motor. I know stuff can happen but, when it does, I would expect the dealer to correct the problem quickly. I have already lost confidence and if they do get it straightened out, I will have to log a number of problem free hours before satisfied.