Yamaha Z250TXRB runs smooth only when fuel priming bulb is squeezed continuously.

[lendebr2012]

I believed that I had stale gas in my fuel tank and drained it (the fuel was stored for about 8 months using Sta-bil gold eagle), replaced all filters except the medium pressure strainer. I also checked the spark plugs and replaced them. When I started the engine, it ran ruff for about 1 minute. After squeezing the fuel priming bulb it ran again for 1 minute. I tried again and kept squeezing the prime bulb the engine ran smoothly as long as I squeezed the bulb.

Can anyone tell me what the problem might be?

[99yam40]

Fuel pumps would be my thoughts

[lendebr2012]

Thanks for your reply. There are two low pressure pumps. I will try to check them out.

[Fragamag]

I had the same problem on my 100 hp Merc.
Found the diaphragm in the fuel pump cracked.
Not real hard to take apart and put a kit in.
Hope you get it fixed.

[lendebr2012]

Thanks for your responses. My problem was fixed by replacing the low pressure fuel pump.