Mercruiser 3.0 PCM-09 Code 3050

mvn

Petty Officer 1st Class
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Jul 25, 2007
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202
We were told in school that you can flood the cat with unburnt fuel or too much oxygen. This is dependent on RPM, load and amount of time doing the test. What engine you’re testing will need to be considered also because of the amount of catalyst material present. 3.0 has one cat, 8.2 has 3 per side, so there is a big difference when dropping one cylinder.

I have been somewhat reluctant to comment on this post because I have never worked on a 3.0 EC engine (no dealer I have worked for would ever sell this package) and I’ve never used Diacom on a MerCruiser EC engine. So please take my comments with a grain of salt.
Ah, that makes sense. My engine does not have cats, only one O2 sensor on each bank. Thanks for the insight.

Mark
 

muc

"Retired" Association of Marine Technicians...
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Pretty much the same thing here Muc but non the less thanks for yours and all the others insight in here because together we learn as that is what these forums are all about. :)

That mentioned, I'm not totally sure myself but worth putting out there to converse...'Would you or anyone here think maybe with the thermostat internals disintegrating like mentioned could flow towards the catalysts causing blockage or damage in that area causing this issue?

Seems either way the catalyst housing needs opened up for inspection.
Anything is possible with the thermostat failure. But it looks like the manifold only got to 214 degrees, don’t think that’s going to kill the cat in a short amount of time.

I wouldn’t recommend opening the Cat housing just yet. It doesn’t appear that the engine has been run enough to complete the Cat monitor tests. I’m not even sure that the O2 sensor replacement fixed that fault or it’s also possible the O2 sensors fixed the OSC problem. Confirmation of all emissions repairs requires 2 run cycles at the RPM and load that the fault was set at. I’m a big fan of using the software that’s already paid for before spending the customers money on new gaskets. EC engine troubleshooting requires a methodical approach, trying to shortcut the process usually results in a bigger bill.
 

muc

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Ah, that makes sense. My engine does not have cats, only one O2 sensor on each bank. Thanks for the insight.

Mark
Your welcome. On this forum, many people try try to be helpful and share the things that worked for them. But most people don’t realize how much engines have changed. Years ago I used to do a cylinder balance test by putting on a welding glove and pulling spark plug wires while the engine was running. Do that on one of these new EC engines and you run the risk of popping a coil, ECM and burning the Cat. Thousands of dollars in damage. These new engines require new knowledge.
 

muc

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Muc - OCS Raw Port and OCS Raw Stbd showing 0.00 mg last time I ran the engine
I don’t think those numbers will show up until you get into full PID and I don’t see anywhere that has happened yet.

Most testing on these engines requires that the engine be running at the speed and load the fault was set at.

I would also recommend that you use the record function in Diacom when doing this test. What you’re looking for can happen pretty quickly and is easy for an untrained eye to miss.

Here is the process I recommend you use.
Starting with a cold engine and the boat securely strapped to the trailer. Back the boat down the ramp until the top of the drive has about 6” above the water. Start the engine, start Diacom recording, let the engine warm up in gear for a few minutes. Now advance the throttle to 2000 RPMs. Let the engine run at this speed until it reaches full PID or you get a fault to set. If you don’t get a fault, repeat this process with the exception of the cold engine and warm up.
 

jnelsonusmc

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Jan 18, 2023
Messages
41
I don’t think those numbers will show up until you get into full PID and I don’t see anywhere that has happened yet.

Most testing on these engines requires that the engine be running at the speed and load the fault was set at.

I would also recommend that you use the record function in Diacom when doing this test. What you’re looking for can happen pretty quickly and is easy for an untrained eye to miss.

Here is the process I recommend you use.
Starting with a cold engine and the boat securely strapped to the trailer. Back the boat down the ramp until the top of the drive has about 6” above the water. Start the engine, start Diacom recording, let the engine warm up in gear for a few minutes. Now advance the throttle to 2000 RPMs. Let the engine run at this speed until it reaches full PID or you get a fault to set. If you don’t get a fault, repeat this process with the exception of the cold engine and warm up.
ok so it appears to me that the catalyst was removed posting picture. I am assuming this is not good right.... stupid question I am sure. Can see the cast iron seam in pic. so there is no way there is a catalyst insert here right?
image0.jpeg
 

mvn

Petty Officer 1st Class
Joined
Jul 25, 2007
Messages
202
Part #38 should be there!
 

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muc

"Retired" Association of Marine Technicians...
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Yes, not good.
Looks like you need a new catalyst and then will need to determine why someone took it out.
 

alldodge

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If the boat never ran correctly then the prior owner may have removed it to sell

Yikes, 2K part
 

jnelsonusmc

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If the boat never ran correctly then the prior owner may have removed it to sell

Yikes, 2K part
Yes I am the sucker on this, bought the boat without sea trial. The boat would not start, I looked at it and immediately saw the distributor was 180 out and noticed a few other minor issues that I knew needed attention, prior owner had just finished rebuilding the engine he said, showed me all the receipts from boats.net for everything he had replaced so I took the chance. He was moving and needed to sell the boat so I got it fairly cheap but after my initial 4K to local repair shop and now this, turns out to not have been a good deal at all.
 

jnelsonusmc

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Yes I am the sucker on this, bought the boat without sea trial. The boat would not start, I looked at it and immediately saw the distributor was 180 out and noticed a few other minor issues that I knew needed attention, prior owner had just finished rebuilding the engine he said, showed me all the receipts from boats.net for everything he had replaced so I took the chance. He was moving and needed to sell the boat so I got it fairly cheap but after my initial 4K to local repair shop and now this, turns out to not have been a good deal at all.
Major lesson learned, never buy a boat without sea trial and never buy a used boat without a diagnostic kit for the engine... costly lesson but at least learning did occur.
 

alldodge

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I've bought from Leaders RPM and got what was posted, no issues so far. Be good to contact as your doing.

Don't think its legal, but could remove the EFI system and install a carb
 

jnelsonusmc

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Jan 18, 2023
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I've bought from Leaders RPM and got what was posted, no issues so far. Be good to contact as your doing.

Don't think its legal, but could remove the EFI system and install a carb
Going the carb route looks like would cost me more than just replacing the catalyst. Want to put it back to working order as easily as possible.
 

jnelsonusmc

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I know what I need to do now, thank you everyone for all the help and advice, I greatly appreciate your time on this. Once I get the new catalyst installed and do a load test I will post back. Will be a few weeks before I can get to this.
 

Fun Times

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Do you by chance still have the original owners phone number? Maybe you can text him a picture of the/a cat and see if he might by chance still have it/the old one just to see if maybe it’s still good or tell him you need it to exchange it for new or something or for more for testing.
 

muc

"Retired" Association of Marine Technicians...
Joined
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Messages
2,065
Do you by chance still have the original owners phone number? Maybe you can text him a picture of the/a cat and see if he might by chance still have it/the old one just to see if maybe it’s still good or tell him you need it to exchange it for new or something or for more for testing.
Yes, this is a good idea. Might help with the question of why it was removed. Inspection of the old catalyst can help with diagnosis.
 
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