Difference between Primer pump and Fuel pump
12-30-2018, 06:37 AM
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Difference between Primer pump and Fuel pump
What is the Difference between Fuel Primer pump and Fuel boost pump?
I saw the Cherokee 180 has Fuel Primer pump and Fuel boost pump either. If they do same thing, why there are two switch?
I saw the Cherokee 180 has Fuel Primer pump and Fuel boost pump either. If they do same thing, why there are two switch?
12-30-2018, 01:45 PM
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The Primer is used during cold engine starts only. The primer manually Injects a small amount of fuel directly into the cylinder head of a carburated engine. Think of the primer as a small “syringe” with a tube that goes directly to one cylinder. The electric fuel pump is for when the engine is running. It is a backup to the mechanical fuel pump and also provides more positive fuel flow during takeoff, landing and switching fuel tanks.
12-31-2018, 08:50 PM
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Originally Posted by PerfInit
The Primer is used during cold engine starts only. The primer manually Injects a small amount of fuel directly into the cylinder head of a carburated engine. Think of the primer as a small “syringe” with a tube that goes directly to one cylinder. The electric fuel pump is for when the engine is running. It is a backup to the mechanical fuel pump and also provides more positive fuel flow during takeoff, landing and switching fuel tanks.
01-01-2019, 12:53 AM
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Originally Posted by Businessjet93
There is mechanical fuel pump but also electronic fuel pump? Why?
PerfInit said why - "It is a backup to the mechanical fuel pump and also provides more positive fuel flow during takeoff, landing and switching fuel tanks." I would add for starting too.
Fuel in low wing airplanes isn't going to move to the engine on its own. An electric pump provides redundancy and fuel under pressure when the mechanical pump isn't working. High wing airplanes use gravity to move fuel to the engine. The odds of gravity failing on any given flight is low enough there is no need for backup.
01-01-2019, 02:42 AM
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Originally Posted by Twin Wasp
PerfInit said why - "It is a backup to the mechanical fuel pump and also provides more positive fuel flow during takeoff, landing and switching fuel tanks." I would add for starting too.
Fuel in low wing airplanes isn't going to move to the engine on its own. An electric pump provides redundancy and fuel under pressure when the mechanical pump isn't working. High wing airplanes use gravity to move fuel to the engine. The odds of gravity failing on any given flight is low enough there is no need for backup.
Fuel in low wing airplanes isn't going to move to the engine on its own. An electric pump provides redundancy and fuel under pressure when the mechanical pump isn't working. High wing airplanes use gravity to move fuel to the engine. The odds of gravity failing on any given flight is low enough there is no need for backup.
thanks for the answer.
But I mean, most of modern automobile have only Electronic fuel pump, not the mechanical fuel pump. I heard that mechanical fuel pump is used for only classic models.
So I wonder why there are mechanical fuel pump even there is electronic fuel pump?
01-01-2019, 05:28 AM
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Originally Posted by Businessjet93
why there are mechanical fuel pump even there is electronic fuel pump?
Be aware that "electronic" does not equal "electrical". There are no transistors in an electrical fuel pump.
Last edited by PT6 Flyer; 01-01-2019 at 05:42 AM.
01-01-2019, 06:48 AM
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Originally Posted by Businessjet93
But I mean, most of modern automobile have only Electronic fuel pump, not the mechanical fuel pump. I heard that mechanical fuel pump is used for only classic models.
So I wonder why there are mechanical fuel pump even there is electronic fuel pump?
So I wonder why there are mechanical fuel pump even there is electronic fuel pump?
01-01-2019, 06:56 AM
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Originally Posted by Twin Wasp
If the electric pump fails in your car (and if it is the only pump) you're stuck on the side of the road. If all you had in an airplane was an electric pump and it failed, where would you be?
High wing: Primary = gravity, backup typically electric (just like two ignition systems).
Low wing: Primary typically mechanical, backup typically electric.
Jets: Lots of fuel pumps.
Same reason some gyro instruments are vacuum, others electric in older planes.
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