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Guardian alarm activates only between 1000-2000 rpm.-gctid373618

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    Guardian alarm activates only between 1000-2000 rpm.-gctid373618

    Since launch last week my 2007 Mercruiser 5.7 liter MPI 350 Mag's Guardian alarm activates between 1000-2000 rpm, otherwise runs fine. Doesn't overheat. My marina's authorized Mercury mechanic replaced water pump but problem persists. He put it on the diagnostic computer which apparently shows low water pressure at 1000-2000 rpm for some unknown reason. He doesn't think its a defective sensor and the thru hull intake screen looks clean. Mechanic is puzzled. Any ideas on what the problem could be? Thanks.

    Anytime the guardian system goes off, it sends a fault code and sound signal which, if your mech has the right computer analyzer, will tell him what the problem is period. no ifs ands or buts... Double check your mech is using the right analyzer. Something is not right with this. Especially if he thought the water pump was the problem... Ask him what the fault code was and then ask what the analyzer says to fix. That computer system is very stable and bullet proof for telling the operator what is wrong and it also tells them how to fix the fault!

    Just a thought but check the oil level... the Guardian system will go off if the oil is a tad low... but it may not be low enough to engage the system to prevent you from idling above 2000 RPM.

    The only other thing to try is to reconnect the harness on top of the engine (left side toward center and almost behind the carb as you look at the engine). Its flat and black with a blue front edge on my 6.2 and I think its the same on your engine.
    Doug ;}
    MMSI: 338068776
    "Go Aweigh to" Photos < click on red letters... 2001 Bayliner 2452 w/6.2 HO (paid for)




      I will ask mech if he is using the correct analyzer.

      His opinion, if I understand him, was that the analyser fault was indicating that the water PSI was reading low between 1000-2000 rpm and that was triggering the Guardian alarm. Since he already replaced the water pump he is puzzled on what to do next. What else could cause low PSI between only 1000-2000 rpm?

      The oil level was actually high & we drained out a quart.

      I will ask him about reconnecting the harness.