Hey all -
Does anyone know how the fuel pump vent system works in the 7.4LX MPI (1996 year) Mercruiser engine? Specifically, if I stuck a pressure gauge on the "sight tube" at the sea water fuel pump what would it read? I think it would read manifold vacuum but I'm not sure. The sight tube vents the mechanical pump to the top of the VST and there's another hose from the VST top to the bottom of the intake plenum. However, inside the VST at the sight tube connection is, I believe, a check valve. This question is based on my intent to replace the mechanical pump with an electrical pump to get away from the problem of leaked fuel into the gear oil. I started wondering if I there is a vacuum on the vent that contributes to the problem. Thanks.
Does anyone know how the fuel pump vent system works in the 7.4LX MPI (1996 year) Mercruiser engine? Specifically, if I stuck a pressure gauge on the "sight tube" at the sea water fuel pump what would it read? I think it would read manifold vacuum but I'm not sure. The sight tube vents the mechanical pump to the top of the VST and there's another hose from the VST top to the bottom of the intake plenum. However, inside the VST at the sight tube connection is, I believe, a check valve. This question is based on my intent to replace the mechanical pump with an electrical pump to get away from the problem of leaked fuel into the gear oil. I started wondering if I there is a vacuum on the vent that contributes to the problem. Thanks.