Low RPM, Slowly decreasing above 2k

[Eddie B]

You would need a Rinda scanner to get the codes, they are $600ish. Problem is that your boat may not be throwing codes if the pump is failing. Mine wasn't, the tech had to put it on the dyno and do a pressure test under load.

You might want to look into the mercruiser vessel view mobile. It connects the engine computer to your phone via bluetooth and gives you fault codes in actual text rather than beeps. Its about $200

Thanks! Does the vessel view require smart craft. It’s a 2003 and I don’t have smart craft. Where can I get vessel view. I was thinking about checking fuel pressure with a gauge. Any suggestions on a good one of those would be welcome as well. Amazon links appreciated ;-)

 

[ColoSR]

Most of the 2003 engines were "Smartcraft Ready" so they have the connector at the engine for the VVM but not the data trunk to the dashboard for smartcraft gauges. Mine is a 2003 6.2L and had the 10 pin connector at the engine so I could plug in there. It is compatible with all the 5.0 MPI's 0M300000 and up, call merc with your engine serial number and they will let you know for sure. You would need the VVM and a yellow cap terminating resistor (~$15) to connect it to your engine.

 

[Eddie B]

Update. So I finally worked up the nerve to try to pressure test the fuel system but I could not find the Strader valve to hook into and didn’t have the moxie to cut into the fuel like. So I cleaned the spark arrester and changed the fuel filter and took her out. She did fine. Full power (or close to it)! I am still going to try to have the codes read, the alarm fixed and a full tune up done. I’ll change the oil myself. But I think I am good to go for now. Really appreciate everyone’s support.


in the end I think the hole in the plug started spraying water all over the engine. It ether got into the spark arrestor, fuel or both and caused the power limit. 5 dollar part could have cost me thousands of not for you fine folks.

 

[Nater Potater]

So I cleaned the spark arrester and changed the fuel filter and took her out. She did fine. Full power (or close to it)! 5 dollar part could have cost me thousands of not for you fine folks.

So good to hear! Thanks for the follow-up.

 

[Dani-Lu]

Hey folks. 2 weeks. Replaced the plug but the boat has not left the dock. I can’t get ANYONE here in Stamford to take her in, read the codes or troubleshoot. Thinking I am going to have to do it myself at this point to save my season. Any recommendations on a decent (code reader)?

You are going deep into the woods, before checking the basics. Change the fuel filter and then go further. If you already did, and I missed your post - never-mind!

 

[Dani-Lu]

Update. So I finally worked up the nerve to try to pressure test the fuel system but I could not find the Strader valve to hook into and didn’t have the moxie to cut into the fuel like. So I cleaned the spark arrester and changed the fuel filter and took her out. She did fine. Full power (or close to it)! I am still going to try to have the codes read, the alarm fixed and a full tune up done. I’ll change the oil myself. But I think I am good to go for now. Really appreciate everyone’s support.


in the end I think the hole in the plug started spraying water all over the engine. It ether got into the spark arrestor, fuel or both and caused the power limit. 5 dollar part could have cost me thousands of not for you fine folks.

Whoops, I typed my prior reply before reading this post. Glad to hear you went with the basics before entering the dark, scary forest! Don't assume the worst, until you have dealt with the most common and usually the easiest fixes. Congrats on your repair!

 

[Eddie B]

Thanks Dani. Lesson learned.