Was it running fine until you took the tank off and filled it? If so, is the hose coupler screwed on the tank all the way? Sometimes the black sealing washer in the tank comes out and gets stuck up inside the hose coupler and then when you screw it back on it doesn't go on all the way. And, also (not to be smart), a real forklift mechanic would be able to diagnois a starting problem on that model forklift in just a few minutes. :-)