I’m having problems getting a dellorto fuel pump to prime with a pulse line any longer than 12″ or so. I ran it once with the fuel pump mounted using rubber isolators just off the cylinder head. It pumped fine that weekend, and the PWM carb ran good other than some fuel coming out of the overflow. 2 weeks later I attempted to move the fuel pump to a location right next to the fuel tank, which of course required a longer pulse line. It wouldn’t pull fuel out of the tank when trying to prime the motor. I moved it back closer to the pulse line, and it still wouldn’t work. So I just rebuilt the pump, and now it works again with a short pulse line, but not a longer one. Any secret to getting it to prime correctly? I tried very stiff and softer pulse lines, no difference. Motor has very good compression, and no issues with a PWK pumparound setup.
Thanks Howie, I took your advice and gave MRC a call. Kudos to Billy. I have never spoken to him before, but he was extremely helpful over the phone, to the point of sending me pictures to help ensure my setup was plumbed correctly. Turns out the plumbing and pump are good, but something was causing a random obstruction in the fuel float valve area. The fuel float valve was stuck, making it impossible to even blow air into the fuel inlet area. After a good cleaning which included some compressed air, and re-adjusting the float, the pump is now working fine and getting fuel to the bowl.