Fuel Rail Pressure
08-16-2013, 11:16 AM
#1
Thread Starter
Join Date: May 2012
Location: Massachusetts
Posts: 7
Fuel Rail Pressure
I know this has been asked before, but I can't seem to find any sort of clear answer. I have a new performance improved engine in my 2000 GT with some aftermarket bolt ons(fuel rails, CoPs, injectors, throttle body, cai, intake manafold, headers).
I am having an issue with CEL P0190(FRPS high) coming on. I have a custom tune on the car from American Muscle, and I have logged the issue with my tuner. I am seeing the frp rang from 34.40 to a max of 40.47, on a 12 minute highway drive. This puts the care in a pre fault state and causes the engine to cut out at around 2500 rpm. I have already replaced the fuel filter, as well as the frps, and have checked the voltages on the sensor connector and everything tests as it should(I have a new engine wiring harness and fuel pump in the car as well).
Does anyone else have any idea's on what to try next? fuel pressure regulator? ecm? I've put a lot of money into this car getting it back on the road and this one little thing is stopping me from really enjoying it.
I am having an issue with CEL P0190(FRPS high) coming on. I have a custom tune on the car from American Muscle, and I have logged the issue with my tuner. I am seeing the frp rang from 34.40 to a max of 40.47, on a 12 minute highway drive. This puts the care in a pre fault state and causes the engine to cut out at around 2500 rpm. I have already replaced the fuel filter, as well as the frps, and have checked the voltages on the sensor connector and everything tests as it should(I have a new engine wiring harness and fuel pump in the car as well).
Does anyone else have any idea's on what to try next? fuel pressure regulator? ecm? I've put a lot of money into this car getting it back on the road and this one little thing is stopping me from really enjoying it.
08-21-2013, 11:08 AM
#2
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
P0190 indicates a problem with the reference voltage (Vref) at the PCM being low--less than 4.0 V--it should be 4.0 to 6.0 V. Read more about P0190 here.
Monitor Vref at the FRP sensor connector:
There is no fuel pressure regulator on the electronic returnless system, the PCM signals the fuel pump driver module (FPDM) to drive the fuel pump as needed to produce the desired rail pressure, based on feedback from the FRPS. Fuel pressure is maintained at 40.0 psi plus manifold pressure (vacuum, a negative value) to maintain the pressure drop across the injectors at 40.0 psi.
If manifold vacuum is high as at idle or closed/partial throttle, let's say 18 inHg (8.8 psi), then the rail pressure will be 40 - 8.8 = 31.2 psi. At WOT where manifold vacuum is low, say 2 inHg (1.0 psi), then rail pressure will be 40.0 - 1.0 = 30.0 psi.
The PCM will also command higher pressure drops, as high as 53 psi, if the fuel is hot (there is a sensor in the FRPS that alters its output when fuel temp is high). This prevents vapourisation of the fuel in the rails.
Monitor Vref at the FRP sensor connector:
There is no fuel pressure regulator on the electronic returnless system, the PCM signals the fuel pump driver module (FPDM) to drive the fuel pump as needed to produce the desired rail pressure, based on feedback from the FRPS. Fuel pressure is maintained at 40.0 psi plus manifold pressure (vacuum, a negative value) to maintain the pressure drop across the injectors at 40.0 psi.
If manifold vacuum is high as at idle or closed/partial throttle, let's say 18 inHg (8.8 psi), then the rail pressure will be 40 - 8.8 = 31.2 psi. At WOT where manifold vacuum is low, say 2 inHg (1.0 psi), then rail pressure will be 40.0 - 1.0 = 30.0 psi.
The PCM will also command higher pressure drops, as high as 53 psi, if the fuel is hot (there is a sensor in the FRPS that alters its output when fuel temp is high). This prevents vapourisation of the fuel in the rails.
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