Our John Deere 450j dozer has a manual fuel pump with a lever. I drained the water trap and figured I would pump the lever a few times. I notice that when I push the lever it has resistance, it is moving fuel. However, I have to wait 12 seconds before pushing the lever moves fuel again. Is this normal? It seems if I had to prime the tractor with this it would take forever.
I'm pretty sure that it's good. If you crack a bleeder open on one of the filter housings you should notice that the lever bounces back up a lot faster as there is no flow resistance. Once that air is out of the system, everything is primed and the bleeders closed, my JD pump levers tend to move slower. I've had several of these 4 & 6 cylinder engines with the same fuel pump. They all respond the same in my experience.
Thank you
Your typical lever operated diaphragm pump does NOT operate the full stroke with every turn of the camshaft, it wouldn't last a day operating like that, the fuel pressure holds the diaphragm back. The spring puts pressure on the fuel via the diaphragm, when fuel flows then the cam pushes the spring back. The priming lever pulls the spring back also, then the spring pushes it out. You don't feel resistance when there is no fuel flowing, because the diaphragm and spring are already held back. Vacuum on the suction side WILL put tension on the priming lever even with no fuel flow.