I have a 2004 Gravely ZT1540 with a kohler courage SV530-0004 15 HP motor. Recently I mistakenly ran the right tank dry and after that I was not able to get it to start from the right tank, after refilling of course. I switched to the left tank and it ran well off that tank. Today I started up to mow again running off the left tank and it started sputtering and acting just like it did with the right tank. I pulled the fuel lines and filter. It seems that I have never thought to replace the in-line filter and the plastic tube was devoid of any filter material and no gas either. I put everything back together and tried to start it again and it seems that nothing is pulling fuel into the lines. My best guess is that it's the fuel pump, but I'm not sure. Any information would be appreciated. Thank you in advance!!