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HELP !!! My Merc 525 EFIs are over revving !!!

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HELP !!! My Merc 525 EFIs are over revving !!!

Old 09-05-2021, 11:22 AM
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Originally Posted by F-2 Speedy View Post
Id say you were down on power and the refresh of the engines picked up 200 rev's, how many hours were on the engines before the refresh ?
I had 560 on them but had them tested and everything was perfect, did the refresh on the head just to be safe.. had a DDT test when bought the boat 8 years back and they were babyíd. I bought the boat with 212 hrs in them, change the oils every 20 hrs etc.

So if the refresh is the cause, should I just reprogram my Pcms to 5400 to get rid of the warning? I donít know that 525ís should be running over 5200 course I could alway just throttle back.

I just get nervous when something like this changes and the mechanic says he has no idea why. And the last think I want to do is blow my engines because they may have been reinstalled incorrectly, that would suck.

Thanks again for your input BrotherÖ..greatly appreciated 😎
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Old 09-05-2021, 11:32 AM
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1. pull back the sticks
2. reprop as Sutphen 30 said
3. remap the PCM's I wouldn't they are set there for a reason, and it will probably cost more than prop's
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Old 09-05-2021, 11:45 AM
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What was the gps speed before and after?

Are you running the same mph as before or is it faster now? Sounds like the engines might have been tired.
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Old 09-05-2021, 11:51 AM
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Originally Posted by F-2 Speedy View Post
1. pull back the sticks
2. reprop as Sutphen 30 said
3. remap the PCM's I wouldn't they are set there for a reason, and it will probably cost more than prop's
Couldnít agree more lol thank you 🙏
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Old 09-05-2021, 11:55 AM
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Originally Posted by underpsi68 View Post
What was the gps speed before and after?

Are you running the same mph as before or is it faster now? Sounds like the engines might have been tired.
Hey bud, I canít answer that because I havenít tested the boat myself, it was taken out for adjustments by the mechanic. It was just what he told me and before I take it out, I wanted to run my problem thought offshore before taking it out this coming Tuesday.

I might change the props if I can gain some top end out of it so long As I donít need a football field length to get planning LOL
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Old 09-05-2021, 02:08 PM
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Why not just send your props out and have them cupped a couple degrees rather than the expense of new props. Just a suggestion! Iíd take the extra 200 rpmís and be great full. Go buy your mechanic a case of beer 🍺
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Old 09-05-2021, 02:16 PM
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IMO YOU need to take the boat for a ride. Maybe the mechanic had it over trimmed?

I wouldn't buy or modify anything till it was confirmed.
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Old 09-05-2021, 02:31 PM
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Maybe youíve shed a bit of weight by replacing the original water logged and heavy wood stringers and transom. That in conjunction with the engines being refreshed may have bought you the extra 200 RPMs. Like others have said, get it out there yourself. Trim it to how you usually do. Note the speed outputs at the higher RPMs and compare to what you previously would achieve.
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Old 09-05-2021, 03:09 PM
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as said above you need to run it. right now we still dont know if the transom itself was replaced in which case they may have raised the gimbal height a little and now we find out you have not run it only the mechanic which means he may be trimming different than you do, etc etc. lot of factors in here that can account for 200 rpms.
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Old 09-05-2021, 03:24 PM
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Originally Posted by compedgemarine View Post
as said above you need to run it. right now we still dont know if the transom itself was replaced in which case they may have raised the gimbal height a little and now we find out you have not run it only the mechanic which means he may be trimming different than you do, etc etc. lot of factors in here that can account for 200 rpms.
Ok, all good points but Iíve trimmed this puppy out to the max at full throttle with all kinds of variables iE. Different fuel levels, passengers, weather conditions etc and could never get past 5200. The entire transom assembly including the gimbals were change as well, I had the stern wall rebuilt with fiber board. But they never removed the outer fiberglass, just everything from the fiberglass skin inwards then in place of using wood and fiberglass, they used fiber board so I never have to worry about rot or humidity again. The thing is, the original holes were used to install all the new parts so itís near impossible for them to have either raised or lowered the position of my drives however,
to your point, it probably wouldnít take much to create a 200 RPM discrepancy 🙄

Iíll run the boat Tuesday and pop back in with an update. Thank you again, I hope you have an awesome day brotherÖ.😎
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