Just had the injection pump rebuilt on a 2010 L4400 and installed it but when trying to bleed it, only got a little fuel out of the 2&3 injector lines but nothing from 1&4 so I decided to check flow from the pump. Pulled the outlet line and got very little flow while cranking. Pulled the inlet line and got good flow so I'm assuming it's a bad pump? Mechanical pump by the way. I'm more of a car mechanic and I'd say pump for sure but with these, I figured I'd ask to be sure. TIA