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7hp no power

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ckdale3

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i have a 7hp evinrude that i b

i have a 7hp evinrude that i bought used it has a lose of power at wide open throttle. i have replaced the plugs cleaned the carb rebuilt the fuel pump and still have the same problem.i can put it in a barrel and run it wide open great but when i put the cowl back on it starts to bogg down. take the cowl off starts to rev back up. there are two small holes in the bottom of the housing for air so im not sure what is happening any help please
 
Most likely experiencing an ex

Most likely experiencing an exhaust leak from a gasket into the cowling. Engine sucks exhaust and not air (oxygen).
 
"i dont hear an exh leak, how

"i dont hear an exh leak, how can i check for this. also with the cowl off if i put my finger over the little vent hole on the carb it seems to have the same result as putting the cowl back on"
 
"to check for a blown power he

"to check for a blown power head gasket run the engine in a tank, squirt some fogging oil in the carb to make it smoke. Look around where the power head bolts to the exhaust housing for smoke coming out between the power head and the exhaust housing."
 
"this may sound stupid but wha

"this may sound stupid but what is fogging oil and will any other type of oil work, atf or machine oil wd40.wher can i get foging oil local. do parts stores carry it"
 
"The quickest way to find out

"The quickest way to find out is probably just to lift off the power head, change base and exhaust cover gaskets. If older than 10 years, change the head gasket as well."
 
i have used the fogging oil an

i have used the fogging oil and found no leaks under the cowl only smokes from the exh at the water. i can lift the cowl up about 1 inch and the eng starts to rev up good. help please. i have been a auto tech for 20 plus years but this has me baffled. 2 strokes are a little new to me
 
"You may keep on testing and s

"You may keep on testing and spend time, but as mentioned above, the shortest, in time consumed, 'fix' is just to lift off the PH and change gaskets. The leak may not be where you think it is and may be difficult to locate."
 
"Run it with a flushing device

"Run it with a flushing device attatched, block the exhaust as best as you can and try the fogging test again...as Morton mentioned, removing the power head on these small motors is quite easy and probably the best way to go. The only difficulty would be with an older motor with excessive salt water corrosion...sometimes those motors don't like to come apart easily."
 
"IS THERE ANY THING ELSE THAT

"IS THERE ANY THING ELSE THAT CAN CAUSE THIS, THE PART STORE IS ABOUT 50 MILES AWAY WOULD LIKE TO MAKE ONE TRIP."
 
Spark plug wire touching cover

Spark plug wire touching cover?...Fuel line getting kinked by cover?...What year and model number???? Take it apart before you buy any parts!
 
"I HAVE CHECKED THE PLUG WIRES

"I HAVE CHECKED THE PLUG WIRES AND FUEL LINES, NO PROBLEM THERE. I WILL GET THE MODEL NUMBER TONITE. IT ACTS JUST LIKE IT STARVING FOR AIR OR FUEL,IF YOU JUST LIFT THE COWL 1 INCH IT RUNS FINE. NOT SKIPPING JUST BOGGS. THE EXH LEAKS MAKES SENSE JUST THINK I SHOULD HAVE SEEN IT USING THE SMOKE TEST.THERE ARE TWO SMALL HOLES IN THE BOTTOM PART OF THE SHROUD AND OPENING AROUND THE SHIFTER SO I THINK IT SHOULD BE GETING ENOUGH AIR. I DO THANK YOU FOR ALL YOUR TIME DONT MEAN TO BE A PEST JUST WANT TO UNDERSTAND WHY."
 
"Sometimes when an engine does

"Sometimes when an engine does not develop enough vacuum, it will not run with the cover in place. This is usually a sign that a rebuild is in order."
 
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