Universal(Kubota) M35 electric fuel pump

[pzmaria]

Hello Members, it might sound like novice question but just recently have noticed that my electric fuel pump is running only when glow plugs are engaged on ignition switch. Once ignition key return to "ON" position fuel pump stops. Is that normal? Shouldn't electric pump run all the time when ignition key is "ON"? It's a second hand boat and just wondering if maybe previous owner rewired something.
Any answers are greatly appreciated.

 

[JoeWhite]

On my 1999 C36, the electric fuel pump runs when engine is running on the M35B. I used a voltmeter to measure the voltage across the fuel pump. You hear the clicking of the pump when you hold the key in glow plug position because the engine is not running and making all that noise. When the engine runs you can not hear it. Measure voltage across the pump to test. The pump power goes through the oil pressure contacts. When the engine runs and oil pressure is developed the switch closes and power is applied to the pump. This circuit is to cut fuel off if oil pressure drops to save the engine from damage.

 

[dlochner]

Is there a mechanical lift pump? The electric one might just be a priming pump to push fuel to the mechanical lift pump. If it is, doesn't need to run when the engine is running.

Follow the fuel line on the engine. If you come to a device with a little lever on it, that's the mechanical lift pump.

 

[Stu Jackson]

I have an M25 engine. The electric fuel pump runs all the time the ignition switch is on. At one time, years after my 1986 boat was built, Universal changed the fuel pump operation to OFF when the glow plugs were pushed but otherwise ON. Unnecessary mod. I recommend having it run always.

Engines 101 - The BIGGEST & BEST collection of M25 Series Universal Engine Information on the Internet, plus some M35, too This includes a link to the Critical Upgrades topic which has more engine information please read it too.

Diesel Engine - c34.org

 

[pzmaria]

On my 1999 C36, the electric fuel pump runs when engine is running on the M35B. I used a voltmeter to measure the voltage across the fuel pump. You hear the clicking of the pump when you hold the key in glow plug position because the engine is not running and making all that noise. When the engine runs you can not hear it. Measure voltage across the pump to test. The pump power goes through the oil pressure contacts. When the engine runs and oil pressure is developed the switch closes and power is applied to the pump. This circuit is to cut fuel off if oil pressure drops to save the engine from damage.

That make sense as there are two wires (+) coming to the pump. one probably coming from the solenoid and the second from oil sensor. Thanks for the info and explanation.