Fuel pump: flow rate vs psi
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From: PNW
Flow is the amount of fuel over a period of time. In this case, if that pump were to run for one hour without anything attached to it, it would have pumped 155 gallons of fuel. (GPH stands for Gallons Per Hour)
PSI is pressure(Pounds per Square Inch). Just like the pressure in your tires. Clearly there's no flowing of anything in your tires, so how could pressure and flow be the same thing? They're 2 completely different things.
PSI is pressure(Pounds per Square Inch). Just like the pressure in your tires. Clearly there's no flowing of anything in your tires, so how could pressure and flow be the same thing? They're 2 completely different things.
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From: Bowling Green KY
Often on fuel pumps you can get a chart to show what the flow rate is at specific pressures, and voltages if they are electric pumps. Most EFI pump flow rates are expressed in liters per hour, and are commonly rated at 3 Bar pressure(about 40 PSI), and at 13.5 volts. The pump you are looking at is a relitively high flow pump, could make over 1000 hp, but is for carbureted vehicles.
That says 155gph@0psi, and XXX_gph@14psi. It doesnt give you that second point to understand the curve. Pumps flow less as pressure increases, and the rate at which they drop off depends on the pump.
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From: PNW
Pressure is pressure. Of course the pump creates pressure. Where else would it come from? This is no different than an air pump. The pump moves a fluid and when it's in a system, pressure builds up. What exactly are you trying to work out here?
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From: Ohio
The pump creates the pressure. Don't believe it? Run a pump straight to the fuel rails (get a pump that uses AN fittings on the outlet and bolt it to the rail with an adapter), put a pressure gauge on the schrader valve, and turn the pump on. Depending on the pump, it could easily see 100+ PSI.
The regulator is a bleeder. It bleeds off excess pressure to bring it down to operating levels.
The regulator is a bleeder. It bleeds off excess pressure to bring it down to operating levels.
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thanks for the replys guys, and one last thing how can the fuel pump generate different levels of psi? from how much voltage or amperage or something it gets??
Also, just to clarify, a fuel pump's flow rate is dependent on the amount of psi its putting out right? as in more pressure = less flow and vice versa
Also, just to clarify, a fuel pump's flow rate is dependent on the amount of psi its putting out right? as in more pressure = less flow and vice versa
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From: PNW
One is not dependent on the other. Clearly you're still trying to figure out the difference between the two. They are two completely different measurements. I think you're confusing how the flow rate of an injector changes with pressure - but the injector is a passive device - it's just a valve. The pump is where your flow and pressure comes from.
I think you need to do some research on fluid dynamics or something because until you can separate those two measurements in your mind, you're never going to understand this.
I think you need to do some research on fluid dynamics or something because until you can separate those two measurements in your mind, you're never going to understand this.
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but people are posting on here that a fuel pump will flow less at a higher pressure and im wondering if thats true
and if it is true then it would suggest that psi and flow are not mutually exclusive
and if it is true then it would suggest that psi and flow are not mutually exclusive
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From: Ohio
More pressure = Less Flow.
A fuel pump alone will run with its pressure uncontrolled. Its a regulator that helps keep a pumps pressure at different levels.
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thank you so much joe that clears it up, and flowrate of a pump is voltage dependent with how fast the motor in it spins right?
and that graph you posted is assuming the pumps are running at the specified voltage of 13.5v?
and that graph you posted is assuming the pumps are running at the specified voltage of 13.5v?
Last edited by 20Silverado03; Jan 3, 2017 at 07:00 PM.
Turn on the garden hose, that's flow. Put your finger over the end, that's pressure.
To increase the pressure, the pump has to work harder and becomes less efficient. As it becomes less efficient, the flow volume decreases.
Like an electric motor, the speed will change as voltage changes. Both pressure and flow will change.
When picking a pump, you want to make sure it will provide the volume you need at the pressure you need, in the worst conditions.
To increase the pressure, the pump has to work harder and becomes less efficient. As it becomes less efficient, the flow volume decreases.
Like an electric motor, the speed will change as voltage changes. Both pressure and flow will change.
When picking a pump, you want to make sure it will provide the volume you need at the pressure you need, in the worst conditions.
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So if you stuck the pump into a tank with the outlet open into the atmosphere that's it max GPH rating. In 1 hr it would push 155 gals out into the air. The pressure rating is running the same but the outlet capped off.
Last edited by RockinWs6; Jan 8, 2017 at 01:04 AM.