Engine surges while driving unloaded,,,,

[300stw]

94 k3500 that i converted to 4911 mechanical injection,, everything runs great except,,,,,
while driving at 1400 to 1900 rpm on flat ground, not up an incline to put a load on motor,
the truck gets a light surge in it, annoying,,,, give a hair throttle or small incline no surge, almost like a governor on a small engine,,,,,,

thoughts,,,,

[racer55]

I would replace the IP fuel return line with clear diesel rated line and watch for bubbles,they indicate air entry between the LP and the fuel level in the tank.

Also verify that the LP is working.

[300stw]

when i installed injection pump i used the lift pump to prime, it was shooting fuel everywhere,,,
any idea where to get the clear line you speak of,,,

[racer55]

Small engine repair shops often have tygon transparent line.F-4040-A is diesel rated.