7040 low power issue

So currently I have the pump tore back off the tractor after going threw all the fuel system again , inlet and return side , checking timing over and over again and making sure I don’t have slack in my gear train , I’ve talked with the guy who went threw the pump he told me to mess the the advance on it , that was to no avail , he’s does not have a test stand apparently to run it on. All he did was tear it down clean it and reseal and assembled it. I was under the impression he could flow check but obviously that wasn’t the case so after talking with a guy who knows the ac tractors more than me and has has several pumps gone threw by Dave’s diesel out of Muncie Indiana , I took the pump off and to them and they can tear it down and flow check it the whole 9 yards.   Suspicious that the cam is in backwards. Time will tell and I’ll post my findings. Thanks to all who commented to help me on this