could someone please clarify for me a problem I have with identifying the correct fuel pump assy for my motor.I have a replacement assy which has three(3) ports & that is what the iboats parts pages indicate, but when I removed my failed one it only has two (2) ports, the diagram for the 78 model 155 has the same part # but shows a two port version is it as simple as it sounds to just block off the third port & run with it or is it a different operating system on this pump?????
All the fuel pumps are 3 port, just different configurations. On the 1977 factory parts lists, it is somewhat confusing-OMC used two types of pumps, depending on HP. That year the 85 hp V4 used (the older version) a different pump than the 115 and 140. The 85 hp version was similar to that used back in the early to mid 70's. It had 3 hose barbs on it. It did not have a hole in the back to mount direct to the block. That pump used a third hose to send the pulse signals to the pump which had 3 hose barbs on it. On that 85 engine the factory put a hose barb on the side of the block for the pulse signals. Your 115 1977 pump is the newer version and should have two hose barbs and a third port (hole) on the backside of the pump. Your pump mounts directly to the side of the block, with a thick oval paper gasket. That backside (third) hole is for the pulses which will activate the rubber bladder inside the pump. Likely the 3-port pump is not the one you need for your applicaion.
thanks emdsapmgr for the excellent info on how the pump works I have made one pump from the two & it works great. you are a genius!!
I'm off fishing to Burrinjuck dam to hunt some great Murray Cod, thanks again