I'd like to start a discussion regarding this fuel pump which was used on some of the early (1996? thru 2002?) OMC 9.9 and 15 HP four stroke engines. This is a mechanically (not vacuum) driven fuel pump. The pump ( 0435352 435352 ) is no longer available but a rebuild kit ( 0435070 435070 ) is available.
I have wrestled with this pump a lot over the past several years. Although it has been a challenge I have had some success and probably can share a lot of tips, tricks, and insights regarding this pump if others are interested.
The biggest problem with this pump is that the diaphragm develops a leak which allows fuel to enter the crankcase leading to poor/no fuel to the carb and a lot of gas in the crankcase. When this happens you must rebuild the pump and change the crankcase oil, including the oil filter. Rebuilding is tricky in several areas and in the beginning I had multiple repeat diaphragm failures (the rebuild kit is now >$75) until I figured out some tricks for properly installing the diaphragm. Not to mention those tricky little check valves that can come loose and then go in backwards if you aren't careful.
Over the years I have accumulated a collection of pumps and parts which have allowed me to learn while keeping this motor running. But, I've also had a bug about trying to replace this dastardly pump with an electric fuel pump. Recently I had success with a prototype that uses the following design concepts: 1) sealing off the fuel pump crankcase port with the modified body of the original pump; 2) using a cheap 12V low pressure electric fuel pump and relay to switch power to the pump; 3) replacing the crankcase oil pressure sending unit with one that has extra contacts to ensure that the pump is only powered when the motor is running, avoiding the fire hazard that can occur if the motor stops and the pump remains powered.
I'd be interested in hearing from people who are familiar with this pump and want to swap repair stories. I'd also be interested in discussing conversion to an electric fuel pump. My current prototype has the pump and relay mounted outside of the hood on a board, and the next step is to install those things under the hood. If there is interest, I will create a follow up post with details and pictures when I get there.
skipt
I have wrestled with this pump a lot over the past several years. Although it has been a challenge I have had some success and probably can share a lot of tips, tricks, and insights regarding this pump if others are interested.
The biggest problem with this pump is that the diaphragm develops a leak which allows fuel to enter the crankcase leading to poor/no fuel to the carb and a lot of gas in the crankcase. When this happens you must rebuild the pump and change the crankcase oil, including the oil filter. Rebuilding is tricky in several areas and in the beginning I had multiple repeat diaphragm failures (the rebuild kit is now >$75) until I figured out some tricks for properly installing the diaphragm. Not to mention those tricky little check valves that can come loose and then go in backwards if you aren't careful.
Over the years I have accumulated a collection of pumps and parts which have allowed me to learn while keeping this motor running. But, I've also had a bug about trying to replace this dastardly pump with an electric fuel pump. Recently I had success with a prototype that uses the following design concepts: 1) sealing off the fuel pump crankcase port with the modified body of the original pump; 2) using a cheap 12V low pressure electric fuel pump and relay to switch power to the pump; 3) replacing the crankcase oil pressure sending unit with one that has extra contacts to ensure that the pump is only powered when the motor is running, avoiding the fire hazard that can occur if the motor stops and the pump remains powered.
I'd be interested in hearing from people who are familiar with this pump and want to swap repair stories. I'd also be interested in discussing conversion to an electric fuel pump. My current prototype has the pump and relay mounted outside of the hood on a board, and the next step is to install those things under the hood. If there is interest, I will create a follow up post with details and pictures when I get there.
skipt
