02 Suzuki 140 df issue with high pressure fuel pump

[Scott1985]

When you turn the key to crank the motor isn't the high pressure pump supposed to cut on for a few seconds then cut off? Mine just continues to run, motor cranks up and runs fine vst is full of fuel and clean fuel at that ...all filters have been replaced including the small filter on the end of the hp pump. Does the high pressure pump continue to run while the motor is running? And info will be greatly appreciated! Thanks

[Solarman]

My motors are the 2 strokes, but all the hp pumps I've seen, build pressure then shut off? Something seems different with yours.

Good luck, someone that knows 4 strokes better should speak up shortly.

[redlowrey]

When you turn the key to crank the motor isn't the high pressure pump supposed to cut on for a few seconds then cut off? Mine just continues to run, motor cranks up and runs fine vst is full of fuel and clean fuel at that ...all filters have been replaced including the small filter on the end of the hp pump. Does the high pressure pump continue to run while the motor is running? And info will be greatly appreciated! Thanks

'' When you turn the key to the on position, the ecu will put a full earth on the fuel pump for about three seconds, if does not receive a signal from the crank sensor it will switch off. When the switch is turned on and to the crank position the ecu will put a full earth or 100% duty cycle on the ground side of the fuel pump wire. When the engine starts the ecu will duty cycle the ground depending on fuel requirements. If you connect up a duty cycle meter and connect it up to the fuel pump circuit, and vary the loads on the engine you will see the duty cycle changing. In simple terms the fuel pump motor is running most of the time. Someone might have wired yours straight to ground, your engine might have been vapour locking.

[Scott1985]

Thanks for the information!!! Very helpful!! So if the high pressure pump constantly runs then it is ok right?.... Motor cranks up and runs without a problem! I'm just trying to rule out anything that could cause the hp to burn up if it wasn't wired to not shut off!! Thanks again and any information will be greatly appreciated!

[seaox230c]

The high pressure fuel pump runs all the time the motor is running. It will not damage it if it continues to run. Excess fuel is dumped back to the return thru the fuel pressure reg. ....If you lost the hp fuel pressure the injectors would close almost instantly. it does shut off when you turn off the motor right?

[Scott1985]

Yes it cuts off when you turn the key off .. I was just concerned about when you turn the key it cuts on but never cuts off. Thanks again for all the info

[redlowrey]

Just to clear the ledger, when I said the pump runs most of the time, we are talking milli seconds in time, there are a thousand milli seconds in one second. Duty cycle is a measurement of time on to time off, not the pump switches off for a few seconds and the back on. the reason the fuel pump is duty cycled is to extend the life of the pump. The ecu duty cycles the pump between 80 and 100%, if you connected up an amp meter in series with the supply wire and the output was at 100% or maximum it might draw around five amps, but when it is at 80% it might only draw around three and a half, this is what extends the life of the pump.

A perfect example of this is when your trolling all day, you don't need the fuel pump to be at it's maximum output, and when you open the throttle the ecu will command the pump to run at 100%.