See attached file.

I'm trying to figure out the path of the fuel flow within the VP44 injection pump (IP). I'm interested in the slight possibility of additional cooling for the IP. Does anyone have any other pics or drawings or diagrams they can upload?

I've done a bit of research on forums and I've talked to BlueChip at lengths. The VP44's computer sits on top of a heatsink or is integral to it, this is bolted to the IP housing, and the diesel fuel passing under the heatsink cools the computer. There is a vane pump at the inlet of the VP44. The "ww.chinahanji.com" drawing is helpful. I'm thinking the area directly beneath the computer, adjacent to the inlet and outlet ports is a cavity and inlet to the vane pump. The fuel enters the cavity thru the inlet port, the cavity is pressurized to 14 psi via overflow valve (or pressure release/check valve, whatever you want to call it) that is integral to outlet banjo bolt. A portion of the fuel is taken from the cavity by the vane pump and fed to the high pressure rotary section of the IP, the rest is returned to the tank thru the overflow valve. This flow of fuel, most of which is returned to the tank is what cools the computer. Does anyone know what the bottom the computer/heatsink looks like?- is it finned or flat? The smaller cavity that the heatsink/computer also covers is shown with what looks like a wire ribbon passing thru and has a seperate gasket. Does anyone know if this is also filled with fuel? Please, are there any VP44 guru's out there that can correct me?

VP44 pics1.doc

When my VP44 died, I was amazed to find out I had to replace the pump with a rebuilt unit regardless of what was wrong. So a bad seal or ruptured diaphragm costs you the price of a rebuilt pump. I started researching the VP44 through several sources including Bosch literature, Bosch flow diagrams, talked twice to a rep from Bosch North America, talked to a few rebuilders and a local guy who has several VP44's in his garage he has disassembled (and modified). I've also spent much time on European website where many people repair rather than replace a radial-plunger distributor pump.

As you can see from the flow diagram, the vane-type supply pump pressurizes the fuel when it is spun by the driveshaft. As engine speed increases, pressure from the supply pump also increases. To keep the pump from developing too much pressure, a regulator valve is used. When the pump develops enough pressure to open the valve (15.2 psi if I remember correctly), some of the fuel is returned to the intake side of the vane pump through a return hole. The flow after the regulator valve is pretty easy to follow with some of the fuel being returned to the fuel tank through the overflow valve.