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Mercury slowing down???

Jerryjerry05

Jerryjerry05

Outstanding Contributor
[FONT=&quot]1995 Mercury 75 hp. 17ft.Ranger Alum. bass boat.[/FONT]
[FONT=&quot]I don't know how to set the timing and don't have a manual for the motor.[/FONT]
[FONT=&quot]The motor seem to runs good and hitting on all 3 cyl, The linkage/throttle is advanced as far as it can go.[/FONT]
[FONT=&quot]Yet the most it gets is 4100 rpm's and 30mph. at wide open and trimmed up.[/FONT]
[FONT=&quot]The load is minimal and no soaked foam.[/FONT]
[FONT=&quot]The prop was changed 6 mo. ago and then it would run 5200 rpm's at wide open and 45[/FONT]
[FONT=&quot]mph.[/FONT]
[FONT=&quot]Checked the timing and it's 12d at idle.(like I said I don't know the specifications for this motor)[/FONT]
[FONT=&quot]??? the owner said it slowly lost rpm's and slowed down to the present speed.??[/FONT]
[FONT=&quot]ANY ideas on why it would slow down??[/FONT]
[FONT=&quot]My first thought was the flotation was water logged but it's not.[/FONT]
[FONT=&quot]My second is the prop 18p.SS was the problem as he said it was changed.[/FONT]

[FONT=&quot]ANY thoughts??? THANKS!!![/FONT]
 
You probably already checked compression? Lower unit failing....binding? How does the gear lube look?
 
You need to time the motor at full spark advance--this is not a car engine!

Remove the cam atop the top carb so you can hold it wide open (about 3,000 rpm).

Jeff
 
Thanks for the reply's.
Done working on it, the owner has some crazy storys about how things developed
and now he changed it ??
Done working on it.
I got it running as best as can be without changing the prop(another story from the owner).
THANKS!!
 
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