Yamaha 15 hp 2cycle will turn over on ether but won't keep running. Fuel runs freely past the fuel filter. Fuel bulb in hose to tank is pumped solid. What should I try next?

It should be possible to test the pump for proper function - there should be no need to replace it hoping for a cure.

A fuel pump should suck at one end and blow at the other and this can be measured using appropriate gauges and if those measurements are satisfactory the amount of fuel pumped can be measured...

Such tests are fairly routine on wheeled vehicles and not only are they a valuable aid to correct diagnosis they remove all doubt when warranty work is involved.

fuel pumps will run constantly when the ignition is on as the pressure regulator is allowing the excess fuel to return to the tank. IF ether fires then you have spark but what you do not have is injector operation. Check for pulse at the injectors and that they are clean and not blocked up

fuel pump should only run for about 15 seconds when u first turn the key on now you should check to see if the fuel filter is clogged or your sending unit might be bad on the fuel pump itself

Do you hold the primer in or pump it? Pumping the primer forces the fuel into the intake bypassing the diaphragm's intended function. Assuming you pump the primer to keep it running your carburetor is dirty and should be cleaned. Ensure that your fuel is fresh and that your fuel can and fuel tank has no water in it. Ethanol in fuel will evaporate and cause condensation thus creating unwanted water.

When you run out of gas in your car, there are a number of parts of the vehicle that can be damaged. For example, running a car without gas can damage the fuel pump, fuel filter, or push dirt through out the fuel line of the vehicle.

What you need to do is remove the air from the injection lines, the reason is when air is in the lines the fuel cannot form enough pressure to open the injectors due to the air compressing instead of being a solid fuel. So first step is to fill the fuel filter.

Next, follow the fuel line from the filter and see if it goes to a small primer pump optional on most machines, if not the go to the injector lines at the injector. Loosen all the lines and apply full throttle making sure the stop is push in SO the machine will run. Crank the motor for 15-20 seconds or until you see fuel pulsating out the loosened lines.

To help protect yourself against risk of running out of gas, consider filling up your tank anytime your fuel indicator falls below 1/4 a tank.

Hope this helps and just keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

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Jose (ZJLimited)

the fuel tap may be causing to problem, if it doesnt turn off it can also flood the engine over night and allow fuel into the sump which then vaporises as it gets hot and the breather allows this fuel back through the air cleaner causing rich mixture

Was it running before the replacement of the fuel lines? Does the primer bulb fill with fuel when pumped? Did you replace the line inside the fuel tank? Check the fuel filter, air cleaner, and muffler for plugging. Hope this helps!

You need to attach a pressure gauge to the schrader valve and measure the fuel pressure with the key on and also while running. You need to see about 40 lbs in both cases.

The fuel system is borderline--fuel pump worn, plugged fuel filter, fuel tank not venting properly. Listen at the tank while someone turns on the key (no start attempt)--you should hear the pump run for a moment or two, then shut off. If it keeps running, the pump is likely worn out. Replace the fuel filter in any case. Pop the fuel cap loose after it starts to run poorly--does that give it another 15 miles? the tank vents through the charcoal canister--not the open air.

replace the fuel filter and spark plug and if 2 stroke check fuel mixture