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Mercruiser 5.7 Guardian Mode

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RedRiverToBlueWater

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I have a 2022 Mercruiser 5.7 300 HP MPI, non-emission repower engine, w/ closed cooling, and Mercury 48 Pin ECM 555.

I had an event and I lost my impeller. The engine was at idle and went into Guardian mode.

I replaced the impeller, cleared codes with Rinda/Diacom. I still had issues. I replaced the pressure sensor, and cleared codes, I still have issues.

From idle, I can rev the engine and get 4K+ RPM's. If I bring the RPM's up slowly, it goes into guardian mode. I can clear the codes and I get the same results.
Horn Output, Overspeed, Guardian, Sea Pump PSI LO, PITOT CKT LO, Fuel LVL CKT HI, FUEL LVL2 CKT H

What am I missing?
Thank you in advance
 
PITOT CKT LO, Fuel LVL CKT HI, FUEL LVL2 CKT H are faults you can ignore if your boat doesn't have those features.

Most faults can be detected with the engine running, or with the key ON but the engine not running. However, some faults
require the presence of engine RPM, and cannot be detected with the key ON but the engine not running. Examples of this type
of fault are EST (cylinders 1 through 8) shorted circuit and all injector faults.
In addition, some faults are programmed to ignore certain engine speeds. For example, the low block pressure sensor fault
(sea pump pressure on a MerCruiser sterndrive) is typically not enabled until enough load has been achieved to develop a
reasonable amount of water pressure. Therefore, this fault will not be set at idle.
Faults also take a certain time to set. The time it takes to set a fault varies greatly and can also vary with engine RPM. Faults
generally set faster at higher engine speed.

So if you have a Sea Pump PSI LO above a certain RPM, it will set the Horn Output, Overspeed, Guardian as a result.

You can use the Diacom to record and watch the sensor output ---- in the water and up on plane. To decide if you have a bad water pressure sender because it got plugged with something when the impeller died or maybe it just happened to die at the same time.
 
From idle, I can rev the engine and get 4K+ RPM's. If I bring the RPM's up slowly, it goes into guardian mode. I can clear the codes and I get the same results.
Horn Output, Overspeed, Guardian, Sea Pump PSI LO, PITOT CKT LO, Fuel LVL CKT HI, FUEL LVL2 CKT H
Click to expand...

You should have an in-gear switch on the shift plate. If the motor is in neutral and the RPMs increase above 1800 or so the alarm sounds, and is normal

Are you testing in the water or on a hose? If on a hose you will have low water pressure at higher RPM
 
THANK YOU for the feed back.
Additional spec information. I am running in-line inboard, closed cooling, with transmission cooler.
When brining it up slowly, it goes into guardian approx. 2,500 RPM (I'm going from memory on this)

When the incident happened, I replaced the impeller and launched and still ended in guardian. I did not have Rinda/Diacom with me.
I got home, put the computer on the engine and I've tested it on the hose. I am able to close by water input thru-hull via sea cock with hose attached at strainer prior to impeller. The engine was running on a water hose, in neutral for testing. I know I had water pressure because the "spray" out the exhaust increased with RPM's. I also know that there were no obstructions as I cleaned out all rubber bits bc they were trapped by the transmission cooler. While running, the pressure reading stayed at ~1 psi regardless of hose pressure or RPM. I assumed that the pressure reading was like the injector test and fuel level sensors; they don't work with a repower engine with ECM555 and/or where sensors don't exist. I did put in a new pressure sensor and test again with same results.
Admittedly, I was reluctant to launch as I didn't want to get stranded in guardian mode. I'm more than willing to take it to water and launch to confirm if it is the in-gear switch.
Anything else I need to consider or confirm prior to launching?

Again, THANK YOU for the feedback and information. I'm at a loss on this one.
 
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