Merc 8.2l guardian seawater pressure fault code 328

[Dave French]

I have a 2013 8.2 and I am getting a repeated guardian code 328 which is for low sea water pressure. I have replaced the raw water impeller (turned out the old one looked fine) and installed a new pressure sender. I am getting around 5 or 6 psi when cruising. I have a Rinda tech tool and when I look at the freeze frame data for the fault the pressure is normal but I do see a bizarre trim position reading recorded in the data set of 278% which is impossible. It reads normally in live data mode. I’m wondering if I am getting a bad trim position reading which makes the computer think the drive is up in the air and therefore receiving no water at the intake. This is definitely not actually happening. Help!

 

[Fun Times]

On your model year application the trim position reading may or may not actually be used but generally I believe it would be more to the being used side especially if your dash gauge system uses digital type read outs… If the trim sensor is connected (plugged in) then you could get an alarm/Code, etc. should something fall out of range… If you look at the sensor wires on the side of the gimbal ring, I believe it or (one) may have 3 wires helping to indicate it may utilize the system to monitor a trim position reading… If connected the readings should be moving on your scan tool vs being in a default stand still setting while trimming the drive.

On the impeller, did you happen to notice if there were any deep grooves inside the impeller housing to where it might be causing a cavitation type issue to where the sensor might be picking up false readings?.. Merc has stainless steel plates that mounts to the inside of the impeller housing that are part of a rebuild kit to help solve some of those types of issues.

Is the inside sensor location all clean of debris…

 

[alldodge]

Not sure what pressure you should be reading but 5 to 6 psi at cruise would seam low to me. I have non-Cat 8.2 MPI and installed a mechanical pressure gauge on the Block, which I get 20 some psi at cruise and around 3 to 5 at idle.

You may have an issue with the poppet valves bleeding off to much pressure.

I'm unable to find a Merc 328 code, just saying because my lack of insight into your issue

 

[Dave French]

On your model year application the trim position reading may or may not actually be used but generally I believe it would be more to the being used side especially if your dash gauge system uses digital type read outs… If the trim sensor is connected (plugged in) then you could get an alarm/Code, etc. should something fall out of range… If you look at the sensor wires on the side of the gimbal ring, I believe it or (one) may have 3 wires helping to indicate it may utilize the system to monitor a trim position reading… If connected the readings should be moving on your scan tool vs being in a default stand still setting while trimming the drive.

On the impeller, did you happen to notice if there were any deep grooves inside the impeller housing to where it might be causing a cavitation type issue to where the sensor might be picking up false readings?.. Merc has stainless steel plates that mounts to the inside of the impeller housing that are part of a rebuild kit to help solve some of those types of issues.

Is the inside sensor location all clean of debris…

So the trim position reads normal and changes as it should when trimming the drive. It’s only in the fault freeze frame that I see the crazy reading. When I rebuilt the pump I used the Merc kit with its new wear plate- it looks perfect. The boat only has 280 hours total.

 

[Dave French]

Not sure what pressure you should be reading but 5 to 6 psi at cruise would seam low to me. I have non-Cat 8.2 MPI and installed a mechanical pressure gauge on the Block, which I get 20 some psi at cruise and around 3 to 5 at idle.

You may have an issue with the poppet valves bleeding off to much pressure.

I'm unable to find a Merc 328 code, just saying because my lack of insight into your issue

If the poppet valves were bleeding off I would see it in the bilge, but the bilge is dry.

 

[alldodge]

If the poppet valves were bleeding off I would see it in the bilge, but the bilge is dry.

No, the poppet valves regulate the amount of raw water used for cooling. If they stick open then the Mans stay cooler then needed or other things. Don't know if your open or closed cooling but here is open cooling. Its for SBC but similar to BBC

 

[Dave French]

No, the poppet valves regulate the amount of raw water used for cooling. If they stick open then the Mans stay cooler then needed or other things. Don't know if your open or closed cooling but here is open cooling. Its for SBC but similar to BBC

It’s closed cooling as are all 8.2’s. The poppets are for draining sea water to winterize which I don’t need to in SC. I think you are thinking about a very different setup.

 

[alldodge]

No Sir, but all good