Bench Test High Pressure Fuel Pump

[Jimmyling]

I have narrowed my problem down to the Fuel Pump inside the Vapor Seperator on a 50HP Mercury 4 stroke EFI Big Foot Outboard. Was wondering what voltage i should be seeing at the terminals of the pump and also is there a way to bench test the pump outside the unit with an external power supply or battery? Thanks for your help

 

[Faztbullet]

Re: Bench Test High Pressure Fuel Pump

Better to keep it on engine for testing as you need the fuel system "closed" to ensure correct pressures. If you have a manual it will show you how to test the pressure and fuel pump..

 

[Jimmyling]

Re: Bench Test High Pressure Fuel Pump

thank you for your response. I guess my reasoning behind the bench check is to eliminate all other variables and just check the pump itself. You think if I hook it up to a 12 volt battery it would be OK?

 

[Faztbullet]

Re: Bench Test High Pressure Fuel Pump

Before you hook up anything whats the engine doing or not doing?

 

[Jimmyling]

Re: Bench Test High Pressure Fuel Pump

I purchased the the boat and the guy told me he used the boat very infrequent and had old gas in the lines for about a year. I changed the gas, and all the filters. I checked the low pressure pump that's run by the water pump and it delivers gas to the vapor separator unit. The unit fills up but the high pressure pump does not turn on. I measured across the terminals and their is voltage there. I did however measure when I disconnected the pump so it was a no load situation. The engine does not start. Thanks for your opinion.

 

[Faztbullet]

Re: Bench Test High Pressure Fuel Pump

Drain the VST tank and remove fuel inlet hose and refill the VST tank with Mercury powertune or BRP carbon guard and let set several days. After setting reconnect the electrical terminals and turn key on and off rapidly to see if pump will jog free, if not replace it. Also clean pressure regulator.

 

[Jimmyling]

Re: Bench Test High Pressure Fuel Pump

Thanks for the advice I'll try that