Ok so my problem is I can't get rid of code p0193.my truck is a 07 f150 lariat 5.4 v3 it runs good just losing gas mileage. I have replaced my fuel pump,fuel filter,fuel pump control module,fuel rail pressure sensor. Has all new spark plugs and coils all parts was replaced with Motorcraft. I've check my wiring at the plug on fuel rail pressure sensor all seems good just don't know what to check next any help would be very much appreciated

 

THAT ain't good enough. P0193 indicates an electronic reading that is NOT rational. Verify the signal output from the FRP sensor is rational / reasonable and gets ALL the way, thru the plug, harness, and to the PCM.

 

How would I go about that

 

Suppose I would start by tracing the Brown/White all the way back to Pin 57 of the PCM. A fuel rail pressure reading from a good scanner (such as Torque Pro) would be helpful too. But the PCM may be 'defaulting' the fuel rail pressure under the Failure Condition, trying to keep your truck running. There are some 'Failure Mode' flags that Torque Pro can check to determine if anything is in Failure Mode Effect Management.

 

Thanks for info I have torque pro not good at it though. But I did get a fuel pressure reading at vacuum manifold of 79 psi but it stays at that even with engine off key on . Can't find how to read fuel psi at fuel rail

 

I would guess 79psi is way to high . Your fpdm should not let it get that high . but thats not an inline mechanical gauge. you are getting it from the fuel rail sensor.So if its wrong so is the reading.

 

I'm not sure how the fuel pressure sensor works, but doesn't it also have a vacuum hose attached to it? I wonder if there is a vacuum leak if it will cause erroneous readings?

 

79 is about right Key ON / Engine OFF. The Fuel Rail Pressure Sensor _DOES_ connect to manifold vacuum - and in fact the reading is "RELATIVE" to intake vacuum. Key On / Engine Running should be around 40. If you disconnect the vacuum line - it is reading relative to atmospheric pressure (not any vacuum) and OBDII reading will jump way up.

The design reasoning for this system is: Fuel injectors are designed to deliver a calibrated amount of fuel with a certain Pressure _ACROSS_ the injector. Since the nozzle is in the intake stream (at manifold vacuum), it must be considered to maintain a 'constant' fuel pressure at the head of the injector (or in the fuel rail). Reading fuel pressure directly in the Fuel Rail is meaningless without considering manifold vacuum.

If your vacuum connection to the FRP sensor is bad / leaky ---- it WILL cause problems (probably the one you have).

 

I've checked the vacum line and no leaks has good suction the 79 psi I'm getting never changes engine off or on

 

Just thought of something I haven't mentioned. Not sure if it matters but my fuel gauge since all this started when I fill up it read empty for about 50 miles then jumps to full and reads right till I fill up again