2000StreetRod
Moderator Emeritus
- Joined
- May 26, 2009
- Messages
- 10,597
- Reaction score
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- City, State
- Greenville, SC
- Year, Model & Trim Level
- 00 Sport FI, 03 Ltd V8
fuel pump types
There are four types of fuel pumps: positive displacement roller cell; positive-displacement gerotor, positive-displacement roller vane; and the turbine. Most manufacturers have switched from the positive displacement pumps to the turbine since they are quiet, do not pulse, and have a longer service life. As I recall the turbine impeller has an electromagnetic clutch allowing it to slip as it comes up to speed (7,000 rpm).
Unfortunately, there are multiple possibilities for the pump running but there being low pressure: if a turbine pump the impeller could be excessively slipping; if a positive displacement pump the drive shaft could be slipping or broken; the pump motor speed or power could be low; the fuel pressure regulator could be defective. A weak pump motor could be due to worn brushes. Since the pump is sealed the brushes can't be replaced.
To isolate between a bad pump vs a bad fuel pressure regulator you could disconnect the pump outlet hose and connect the outlet to a pressure gauge. The pressure should increase to 65 psi within a few seconds after energizing the pump. Do not let the pressure increase above 80 psi.
There are four types of fuel pumps: positive displacement roller cell; positive-displacement gerotor, positive-displacement roller vane; and the turbine. Most manufacturers have switched from the positive displacement pumps to the turbine since they are quiet, do not pulse, and have a longer service life. As I recall the turbine impeller has an electromagnetic clutch allowing it to slip as it comes up to speed (7,000 rpm).
Unfortunately, there are multiple possibilities for the pump running but there being low pressure: if a turbine pump the impeller could be excessively slipping; if a positive displacement pump the drive shaft could be slipping or broken; the pump motor speed or power could be low; the fuel pressure regulator could be defective. A weak pump motor could be due to worn brushes. Since the pump is sealed the brushes can't be replaced.
To isolate between a bad pump vs a bad fuel pressure regulator you could disconnect the pump outlet hose and connect the outlet to a pressure gauge. The pressure should increase to 65 psi within a few seconds after energizing the pump. Do not let the pressure increase above 80 psi.