Fuel Pressure From The Fuel Pump

[dans new toy 3]

Hi what should the pressure be from the fuel pump to the pressure regulator ?

 

Thanks dan

[Anthony 1,003]

Whatever the FPR is rated to - usually it's 3 bar above manifold pressure (ie so it'll be less than 3 bar at idle)

[dans new toy 3]

Cheers mate so the pump itself will only produce 3 bar of pressure ?

[Tom Fenton 1,541]

The pump provides a flow of fuel, it does not make pressure. The pressure is created by the fuel reg, which restricts the flow of fuel, which causes the back pressure if you like to build up. When the pressure n the line between pump and reg reaches the preset level a plunger in the fuel reg pushes against a spring and allows some flow back to the fuel tank.

 

What is the issue you have?

[dans new toy 3]

O right I understand now thanks. The problem is my engines been running rough/jerky under load as it's running lean I've changed the afm and checked for air leaks and still no luck. I've been told it could be my pump on its way out so I was wondering if there's any way of checking it through pressure ?

The engines a 1.9 mi16

 

Thanks dan

[Tom Fenton 1,541]

You can check the pressure to see if this is an issue. You would need to fit a gauge that you can see when driving then see what it does when you have a problem. Typically if the fuel pump is an issue you would notice it when there is more demand on the pump e.g. Higher up the rev range.