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Peter Bagley
Peter Bagley, Toyota mastertech
Category: Mercury
Satisfied Customers: 681
Experience:  master tech at Toyota dealer
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Carburator Problem, I think. 40 HP Mercury Outboard. Serial

Customer Question

Carburator Problem, I think. 40 HP Mercury Outboard. Serial #0T518752,
Model #1041412ZDMotor starts and idles for a short while, then stalls out. If I pump the rubber bulb from the fuel tank, motor will pick back up and run a while longer, but eventually stalls. Also, If I depress the choke while idling, this keeps it running a little longer.I took the carburator apart and cleaned it but did not replace any parts.I have not put the motor in gear because I am sure it will stall immediately. I am using new gasoline and hose and am sure the gas tank is clean, also the tank is vented.My novice opinion is that there is a disruption in deliver of fuel to the motor. But, I do not know if I should buy a new carb or try to replace the parts from a kit.
Submitted: 9 months ago.
Category: Mercury
Expert:  Peter Bagley replied 9 months ago.

Hello and welcome to just answer. I value your input to my questions so I may serve you better.If you can keep it running squeezing the bulb your supplying fuel pressure and in a essence over riding the fuel pump. Mos t likely the fuel pump diaphragm is shot ,they tend to dry out in storage and need replacing. also make sure you adjusted the fuel mixture needle on the carb just right. Most of these problems occur when they are not stored right with using a fuel stabilizer and fogging the engine. Check all your fuel lines for cracks and kinks , I would even replace them at that age for safety they don't last for ever. Then replace tour fuel pump diaphragm. Hope this helps give you some direction to solve your issue and if you require further assistance I'll be happy to do so.

Customer: replied 9 months ago.
I just ordered the fuel pump kit, but Wholesale Marine said their system pulls up a kit that is different than your photo. It has more part to it.
Expert:  Peter Bagley replied 9 months ago.

probably does because I just used a generic one to show you what I was talking about and didn't have your true model and serial number .As long as they get you the right one with your info that should solve your problem.

Customer: replied 8 months ago.
Peter, OK. I have rebuilt the fuel pump and yes the insides did appear a little worn. I noticed that the fuel pump kit included both a white check valve disks and a black rubber ones. Since the existing pump had only the white disk, I did not use the black rubber ones.The motor starts up very quickly, but continues for about 30 seconds and quits. I notice that if I depress the electric choke switch (at the ignition key) and let off, the motor will pick up and run. If i repeat depressing the choke periodically , it will run for a continued period of time.So, now I wonder if I need to focus back on the carb again -- I only cleaned it before but did not replace any internal parts.Should I buy a kit and rebuild the carb? Should I replace it completely ? Otherideas ?Thanks,
Expert:  Peter Bagley replied 8 months ago.

perhaps that would be a good idea because it's still fuel related, there is another thing that comes to mind as well being if it's a two stroke it may have a vacuum leak around the case . but what i would do first is put some good fuel system cleaner in the fuel and run it as much as you can , check the mixture screw that it's set properly, rebuild the carb.and if all that don't work you may have to have it checked for vacuum leaks.

Customer: replied 8 months ago.
Ok thank you will try that.
Expert:  Peter Bagley replied 8 months ago.

let me know your results.