On my 2003 fat boy all oil from tank is in engine and won't return whats the cause ? runs real rough

The scavenge portion of your oil pump is not working for some reason. The old Ironhead Sportsters were notorious for this. But, the gears in the oil pump were driven by these small pins. Any bit of trash that got into the pump would shear the pin of the scavenge gears and the feed gears would pump all the oil into the engine but the scavenge gears could not pump it out and back to the tank.



The Big Twins would do it as well but they used small keys to drive the gear. The ' Evo models were bad about breaking a tooth off the plastic breather gear. The tooth would wind up in the scavenge gears of the pump and then the main drive key would shear stopping the pump altogether.



I wish I could tell you more about your pump but due to my limited knowledge of the Twin Cam oil pump, the only thing I can tell you to do is to take it someone who know what he is doing in that area.



Good Luck

Steve The scavenge portion of your oil pump is not working for some reason. The old Ironhead Sportsters were notorious for this. But, the gears in the oil pump were driven by these small pins. Any bit of trash that got into the pump would shear the pin of the scavenge gears and the feed gears would pump all the oil into the engine but the scavenge gears could not pump it out and back to the tank.

The Big Twins would do it as well but they used small keys to drive the gear. The ' Evo models were bad about breaking a tooth off the plastic breather gear. The tooth would wind up in the scavenge gears of the pump and then the main drive key would shear stopping the pump altogether.

I wish I could tell you more about your pump but due to my limited knowledge of the Twin Cam oil pump, the only thing I can tell you to do is to take it someone who know what he is doing in that area.

Good Luck
Steve

A seldom talked about Twin Cam engine problem is crankshaft shifting. Unlike the Evolution and Shovelhead cranks, the TC crank is a press-together unit where the crankpin is a "hard" press fit into the two flywheels halves. Under most circumstances, this design works well. However, in some cases, under hard deceleration and acceleration or ground-pounding tire burnouts, the three-piece pressed-together crankshaft can twist out of true, sometimes as much as .030-inch, or even more in the worst situations. Ideally, the crankshaft should be trued during assembly to within .001-inch. Under high power and torque conditions, a TC's flywheels can shift on the crankpin, causing the crank assembly to become severely out of true. This results in a severe wobbling of the right-side pinion shaft, which is located in the camshaft's gearcase. A wobbling pinion shaft often causes catastrophic damage to the engine's oil pump and cam support plate along with a loss of oil pressure and oil scavenging. Early warning signs include loud noises from the engine's gearcase area, ticking lifters, and oil dumping out of the cylinder head breathers. A seldom talked about Twin Cam engine problem is crankshaft shifting. Unlike the Evolution and Shovelhead cranks, the TC crank is a press-together unit where the crankpin is a "hard" press fit into the two flywheels halves. Under most circumstances, this design works well. However, in some cases, under hard deceleration and acceleration or ground-pounding tire burnouts, the three-piece pressed-together crankshaft can twist out of true, sometimes as much as .030-inch, or even more in the worst situations. Ideally, the crankshaft should be trued during assembly to within .001-inch. Under high power and torque conditions, a TC's flywheels can shift on the crankpin, causing the crank assembly to become severely out of true. This results in a severe wobbling of the right-side pinion shaft, which is located in the camshaft's gearcase. A wobbling pinion shaft often causes catastrophic damage to the engine's oil pump and cam support plate along with a loss of oil pressure and oil scavenging. Early warning signs include loud noises from the engine's gearcase area, ticking lifters, and oil dumping out of the cylinder head breathers.