problems w/ Mercury engine

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JCT

.
May 16, 2005
15
Macgregor 26X Rocky River, OH
I have a 50 horse 4 stroke Mercury Bigfoot engine. Had problems with low speed - the mechanic changed coils, adjusted the carberetors. I had previously changed the spark plugs and oil. Now low speeds are fine but the high end is running rough, despite several adjustments.
 

Raftco

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Sep 23, 2009
59
Catalina 30 MKII, Fin Keel Harwich Port, MA
Check for water in the gas. Completely flush the fuel system, there is also a water/fuel seperator on the actual engine that can be replaced, you can bleed the lines by pushing on the small tire pressure looking fittings, and replace your gas with fresh gas if you can - otherwise put some dry gas into the system. Also, Mercury makes a product called 'Quickleen' that will help clear out a lot of the gunk in there - add an ounce to 6 gallons of gas. If you don't have one, add a fuel/water seperator next to the outboard mount - you'll be surprised how much water is in fuel when you can see it and that will allow you to drain it periodically.

The newer engines are extremely tempermental with gas because their consumption is so much lower than the old 2 strokes which would discharge any of the fuel/water/oil they didn't burn. If any water gets into the fuel system they want to shut down. Very frustrating! I use Mercury engines commercialy, and have 2 50hp 4 strokes and a 75hp optimax that had water issues this past summer from rain that got into the tanks. All three engines needed to have the fuel & water flushed out, filters changed, etc. and then they were good as new. Find a good Mercury dealer who knows their stuff and can take care of you, but I have a hunch that might be your problem.
 
Sep 8, 2009
171
Island Packet 31 Cutter/Centerboard Federal Point Yacht Club, Carolina Beach, NC
1
 
Last edited:
Sep 25, 2008
992
Oday 25 Gibraltar
Ahoy JCT,

Raftco definitely has the experience! We added a fuel/water separator filter to the transom of our small sailboat, because we listened to experienced boaters like Raftco. We also use a fuel stabilizer. Ethanol in fuel is not good for outboards! Good luck!

David

Which fuel/water separator did you install?
 
Sep 8, 2009
171
Island Packet 31 Cutter/Centerboard Federal Point Yacht Club, Carolina Beach, NC
Fuel/Water Separator Filter Kit

Which fuel/water separator did you install?
Ahoy RBone,

The following web address shows the Valmar Marine Universal Fuel/Water Separator Filter Kit:

http://www.valmarmarine.com/productdetail/ProdDetail-34020.asp

Purchased our Valmar Marine Universal Fuel/Water Separator Filter Kit at a Carquest Auto Parts store.

Works great! Was very easy to install. Had to purchase two brass hose barb to MPT fittings, two ss hose clamps, and two 7/16" x 1 1/2" ss bolts/fender washers/locknuts.

The Universal Fuel/Water Separator Filter Kit was about $30. The mounting bracket is cast aluminum.

Fair weather!

David
 

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