Re: Stuck hydraulic for assisted tilt in 40hp

[Casey Lynn]

Your questions on the VRO system are easy.
Think of three pumps….all connected by a central stainless steel shaft.
The largest chamber houses the air motor, kind of an old school power brake booster arrangement with a large diaphragm that is moved in one direction by the vacuum and pressure pulses the engine produces. Check valves keep it moving in the same direction until it hits a stop which opens a flapper and the diaphragm is returned to the ready or start position to start the travel all over again. This scenario is for when the pump needs to supply a large amount of fuel and oil for very advanced throttle settings. Works a little different at low RPM/throttle settings but basically the same.
The central shaft also connects a second diaphragm in the second chamber. This is the fuel pump. It is huge compared to the small stand alone fuel pumps we normally talk about on here and really doesn’t work very hard to produce fuel for the smaller engines. Again a set of check valves allow the fuel in at the bottom and out at the top.
In the third chamber, also connected by the same central shaft, is an oil piston. There is lost motion built into the piston which allows the "Variable Ratio Oiling" or "VRO" This is a very short version of what goes on in the pump but the pump is pretty simple and makes an excellent stand alone fuel pump.

Should you want to disconnect the oil function simply disconnect the oil supply from the pump and close off the open hose with the supplied yellow plug. Disconnect all the wiring from the pump and the oil tank and you are done. Nice and simple.