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48spl only running on bottom cylinder

M

mmiller90

New member
my 1990 evinrude 48 spl is only running on one cylinder. compression is 125 on both cylinders and have spark on both plugs jumping at least a 7/16" gap and the top cylinder is getting fuel. what is going on
 
Did this problem start suddenly ?-------If so was it at full throttle ?---- Testing to be done.------Does the primer bulb go hard , yes or no ?------Remove cover in front of carburetors.---Squeeze bulb, does any fuel leak out.------Perhap a reed valve is broken ( extremely rare ) or something is stuck in a reed valve.----A ruptured diaphragm in the fuel pump would flood the top cylinder with too much fuel.----That means it won't produce power.
 
Racer has probably got your answer. What else could it be? Have you had a mouse nest? Insulation from cowling can break loose over time too. Once it starts to fail you have to get rid of all of it or it can lodge into a reed and then " bingo"........I think we have a little problem. I have cleaned hundreds of cowlings from broken down insulation. Once I repair a motor I NEVER want to see it again. If the customer doesn't want to do it MY way, he can bring it to a shop with less experience.
 
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But the OP has told us that the " top cylinder is getting fuel "------So perhaps we need to assume that the poster is wrong !----Some 50 years ago folks came to the shop with totally wrong ideas / assumptions on their motors.----Perhaps it is still true today !
 
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