Fuel Pressure
#1
09-19-2015, 11:33 PM
Join Date: Aug 2015
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Fuel Pressure
2000 Dodge Stratus SE – 2.4L w/157,000 Miles
I recently conducted a fuel pressure test on my vehicle. For some time, my vehicle has been plagued by a PO171 – Lean Fuel Condition engine code. After other tests and new parts, we have come to suspect the fuel system as the culprit.
According to the vehicle’s specs, the fuel pressure for this vehicle should be 49 psi. My vehicle tops out at 31 psi. When cycling the key three times (key on, engine off) a pressure of 31 psi was produced. Additional cycling of the key did not result in greater pressure.
The vehicle was then started after resetting the fuel pressure gauge. At idle, the vehicle again produced a pressure of 31 psi. When revved to 2,000 RPM’s, a pressure of 31 psi also resulted. When left to sit an hour, the pressure dropped to zero (drops a little more than one half pound per square inch per minute). Is this normal? Should a fuel system depressurize when the vehicle is turned off? A leaky fuel injector was ruled out which leaves the fuel filter, fuel regulator and fuel pump as possible culprits.
I recently conducted a fuel pressure test on my vehicle. For some time, my vehicle has been plagued by a PO171 – Lean Fuel Condition engine code. After other tests and new parts, we have come to suspect the fuel system as the culprit.
According to the vehicle’s specs, the fuel pressure for this vehicle should be 49 psi. My vehicle tops out at 31 psi. When cycling the key three times (key on, engine off) a pressure of 31 psi was produced. Additional cycling of the key did not result in greater pressure.
The vehicle was then started after resetting the fuel pressure gauge. At idle, the vehicle again produced a pressure of 31 psi. When revved to 2,000 RPM’s, a pressure of 31 psi also resulted. When left to sit an hour, the pressure dropped to zero (drops a little more than one half pound per square inch per minute). Is this normal? Should a fuel system depressurize when the vehicle is turned off? A leaky fuel injector was ruled out which leaves the fuel filter, fuel regulator and fuel pump as possible culprits.
#2
09-20-2015, 04:09 AM
From the CSM, Fuel System:
"The in-tank fuel pump module contains the fuel
pump and pressure regulator. The pump is serviced
as part of the fuel pump module. Refer to Fuel Pump
Module.
The fuel delivery system consists of:
² the fuel pump module containing the electric
fuel pump, fuel filter/fuel pressure regulator, fuel
gauge sending unit (fuel level sensor) and a separate
fuel filter located at bottom of pump module
² Fuel tubes/lines/hoses
² Quick-connect fittings
² Fuel injector rail
² Fuel injectors
² Fuel tank
² Fuel tank filler/vent tube assembly
² Fuel tank filler tube cap
The fuel delivery system contains a replaceable inline
filter. The filter attaches to the frame above the
rear of the fuel tank."
In all probability the problem is the pump. It wouldn't hurt to change the filter, but I think a dirty filter is going to affect flow more than it will pressure.
"The in-tank fuel pump module contains the fuel
pump and pressure regulator. The pump is serviced
as part of the fuel pump module. Refer to Fuel Pump
Module.
The fuel delivery system consists of:
² the fuel pump module containing the electric
fuel pump, fuel filter/fuel pressure regulator, fuel
gauge sending unit (fuel level sensor) and a separate
fuel filter located at bottom of pump module
² Fuel tubes/lines/hoses
² Quick-connect fittings
² Fuel injector rail
² Fuel injectors
² Fuel tank
² Fuel tank filler/vent tube assembly
² Fuel tank filler tube cap
The fuel delivery system contains a replaceable inline
filter. The filter attaches to the frame above the
rear of the fuel tank."
In all probability the problem is the pump. It wouldn't hurt to change the filter, but I think a dirty filter is going to affect flow more than it will pressure.
#3
10-11-2015, 07:24 PM
Join Date: Aug 2015
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After my last post about a month ago, I finally found the time to address my fuel pressure problems. I decided to replace the entire fuel pump assembly as it was both time and economically sensible. Buying each individual part would have cost a fortune.
The two culprits that were the cause of my poor fuel pressure were more than likely the external fuel filter and in-tank strainer. The external fuel filter when blown-out using an air compressor release a stream of gasoline and sediment (rust?) black as the midnight sky. Once cut open, it revealed an somewhat sticky oil-like substance.
The in-tank fuel strainer wasn't in much better shape. When squeezed, it released a flow of gasoline which wasn't much cleaner, just minus the sediment. How either of these parts picked-up such contaminants is beyond me. The tank appeared clean inside and so did the gasoline that was drained from the tank but I decided not to take a chance and thoroughly clean it considering a new fuel pump was being installed.
The two culprits that were the cause of my poor fuel pressure were more than likely the external fuel filter and in-tank strainer. The external fuel filter when blown-out using an air compressor release a stream of gasoline and sediment (rust?) black as the midnight sky. Once cut open, it revealed an somewhat sticky oil-like substance.
The in-tank fuel strainer wasn't in much better shape. When squeezed, it released a flow of gasoline which wasn't much cleaner, just minus the sediment. How either of these parts picked-up such contaminants is beyond me. The tank appeared clean inside and so did the gasoline that was drained from the tank but I decided not to take a chance and thoroughly clean it considering a new fuel pump was being installed.