Mercury 4 stoke engine revs dropping

M

madfish60

Recruit
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Jan 29, 2011
Messages
3
While motoring back in recently and cruising at a constant revs the motor seemed to reduce revs and struggle intermittingly. I have checked the fuel filter for water and found none. Any ideas?
 
Faztbullet

Faztbullet

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Mar 2, 2008
Messages
15,616
Re: Mercury 4 stoke engine revs dropping

What hp? Carb or EFI? Do you have a tach? How many rpms does it loose?
 
snowman48047

snowman48047

Petty Officer 1st Class
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Jul 24, 2008
Messages
371
Re: Mercury 4 stoke engine revs dropping

You say fuel "filter". I had this same issue with my 50 Merc. Would run maybe a couple hundred yards then lose 2000rpm, then pick up, then stall. I found out there was a fuel filter I never knew about. Removed maybe 6-8 screws and the left side cover (not the hood) and that filter was 80% blocked. Looks just like an older white plastic auto fuel filter. There are 2 fuel filters on my 2001 50hp. I guess 600 hours on a fuel filter is bad...
 
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madfish60

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Jan 29, 2011
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3
Re: Mercury 4 stoke engine revs dropping

Just to clear this one up. I took the boat to my service agent and they found traces of ethanol in the fuel which was causing the problem, I will now contact the service station where I last filled up to give them grief, my service agent said some stations are worse than others for this!
 
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mxr133

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Nov 18, 2009
Messages
2
Re: Mercury 4 stoke engine revs dropping

madfish60 said:
While motoring back in recently and cruising at a constant revs the motor seemed to reduce revs and struggle intermittingly. I have checked the fuel filter for water and found none. Any ideas?
Click to expand...


check spark plugs?
 
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