We have a multifuel, non-turbo that simply won't start. I get plenty of fuel to the injector pump (in-tank pump works fine), checked the fuel shut off lever under the pump cover (everythine is fine there), and removed the plug from the center of the hydraulic head. With the plug removed, I get alot of fuel out the hole with the switch on. I checked pump operation with a wooden stick in the center hole, everything moves as intended, but no fuel at all if I pull the injector lines at any of the injectors. The truck was getting kind of hard to start, and seemed to be losing a little power, especially when cold. Bad injector pump? Any advice would be helpful.