Quote:
Originally Posted by Bio240D
Hi All!
The only purpose of the lift pump is to supply fuel to the pumping elements at a high enough pressure to ensure the element cylinders are completly full before the plunger moves up to close off the inlet port. Anything above that pressure makes no difference since fuel is basically incompressible, so you cant squeeze any additional fuel into an already full cylinder. The volume of the cylinder is what determins how much fuel will be injected and therefore the amount of power produced.
Now maybe at insanely high rpm you could possibly run into a situation where there wasn't enough time for the cylinder to fill completley. This would cause a loss of power due to the cylinder not being full. Then additional lift pump pressure would help because the fuel would fill the cylinder faster due to the increased pressure.
I don't know if our engines can turn fast enough for this to be a problem or not! I hope this helps!
Cheers!
Chris
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That is also what happens when the Fuel Pressure is to low. The Element does not have enough time to fill.
There is also a lot of turbulance and pulsation going on inside of the Fuel Injection Pump Housing because each Element also expells Fuel out of the Feed Port. So there needs to be enough pressure and flow so that that turbulance does not interfere with the filling of the Element.
There is also supposed to be enough volume going through the Fuel Injection Pump to cool it.
Although there are Inline Fuel Injection Pumps on other Engines that do not have retun Fuel from the Fuel Injection Pump Housing. However, they use Diaphragm Fuel Supply/Lift Pumps and you need to open a Screw to Manually Bleed the Air out of Them.