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40 hp mercury engine trouble

M

MBC

New member
I have a 1996 40hp mercury 4cylinder. It was running great through last year. Took it out this year and it only runs up to 3k rpm, normally it goes to 5k at full throttle. Engine starts fine, idles fine. The only way I can make it run at full power is to push the key in. Which is the enrichment valve or choke. Then it runs great, full rpm full power. That is the only way it will work, I have replaced the fuel filter, made sure there is good fuel flow up to and past the filter. Anyway I am stumped. Any help would be greatly appreciated.
 
Having to use the enricher means you have a fuel blockage.--------------I suggest a proper dismantling and cleaning of carburetors.-------------Running an outboard like yours with a blocked carburetor can lead to major damage.---No gas going into the engine means no oil as well.
 
guyjg said:
Fuel pump may be failing...poor flow at high RPM.
Click to expand...


Ok I will check that, but why would it run perfect when I push the choke in. I know that dumps fuel into the top of each carb. The choke is inline after the fuel pump, it gets fuel from the top carb, I don't think the fuel enricher (choke) is an actual pump, it looks like an electronic valve that opens and allows fuel to go directly into each intake. Thank you very much for your help, I am stumped. I will do the fuel pump, but if it is bad I don't understand how the carbs are getting gas to feed the choke.
 
racerone said:
Having to use the enricher means you have a fuel blockage.--------------I suggest a proper dismantling and cleaning of carburetors.-------------Running an outboard like yours with a blocked carburetor can lead to major damage.---No gas going into the engine means no oil as well.
Click to expand...

OK thank you for helping me
 
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