1987 Mercury 20XD fuel system

zackduncan40

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So I?m stumped right now on what is wrong with my motor. I have Replaced all adaptors in fuel line and put a new fuel primer bulb in my line and my motor will still only run if i am Sitting there pumping the bulb. The bulb will never get hard like it did before it stays soft. Can anyone give me any tips to try and fix this problem? And also does my engine have a fuel pump? And if so could that be my problem? Thanks
 

racerone

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Yes the motor has a fuel pump.---It is part / attached to the carburetor.----Best to check it.-----When operating the manual pump the fuel must be going somewhere.------Any leaking out the exhaust ?
 

zackduncan40

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Do you know a part number for the fuel pump racerone? And no it?s like it isn?t even making it to the carb or something and is just bubbling air into the fuel tank
 

Scott Danforth

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Sounds like fuel pump is shot. Kit is under $10
 

flyingscott

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Rebuild the carb with a complete gasket set. If the fuel pump has failed the primer will soon follow.
 

racerone

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You say ---" sounds like bubbles going into the tank "-----Not right and you should investigate that.
 

zackduncan40

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Thanks for all the input guys, i will order a complete rebuild kit and i will Update if the problem continues after the new carb kit
 

zackduncan40

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I?ve been looking online and i cant Find a kit with the fuel pump stuff and everything... can someone get me a part number for the kit that i need To redo the carb and fuel pump?
 

racerone

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Well, ----" online " does not have much repair experience.----Visit / support your local Mercury dealer who may help with that issue.----Have the serial and or the carburetor # handy.
 
Last edited:

flyingscott

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That carb kit was used for over 15 yrs on a lot of motors. I believe this is the # 1395-9761 1 you need to double check that against your serial #.
 

zackduncan40

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Update: i put all the new diaphragms and new gaskets in the carburetor and it is still doing the same thing as before. It runs fine but runs out of fuel.. it will still only stay running if you keep pumping the primer bulb. The primer bulb will get hard like it is full until i start The motor and then it runs out after just a little bit. So I?m stumped guys.. what other problems might i have To cause this to happen? Thanks in advance
 

flyingscott

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Is the base gasket for the carb on correctly? Is the correct base gasket used?
 

racerone

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Fuel pump diaphragms are " driven " by crankcase compression.-----If that is not there the pump does not work.----I am not there to check it out.---Up to you to look into that issue.
 

zackduncan40

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Okay so today i noticed something... i was Driving my boat and the gas tank is like sucking in on its self... and when i unscrew the tank lid the tank expands back out to normal... do you guys think my problem is my fuel tank maybe? Is the tank supposed to be sealed or am i supposed To vent it?
 

racerone

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Test run with another tank and hose.-----There is a blockage it appears.----Tank should be vented !
 
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