MerCruiser Engine (replaced 2019) RPMs Drop After 50 minutes

JFerna

Recruit
Joined
Jul 25, 2025
Messages
1
2003 Regal 4260
Running 3,500 RPMs 19 knots for 50 minutes
RPMs dropped to 2,500, then 2,000 then 1,000
Temp. steady at 165 - 170
After limping home at 8 knots, next day ran 20 minutes no issues
Checked gas - no water
Manifolds replaced 3 years ago (low hours - 100)
Replaced fuel line, installed new fuel filter and new low pressure and high pressure fuel pumps
Sea trial no issues after 50 minutes
Any ideas / recommendations?
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
43,144
Welcome

Moved your thread to the Mercruiser section so it will get more views, and don't see a Regal 4260 having outboards

How about let us know what motor are you discussing and motor serial numbers are best
 
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