P0193 Code

[rgorke]

i had this high fuel pressure code come on yesterday while driving. Well more accurately, coasting.

I have 2004 V8 that has been running great. After the light came in, I plugged in my trusty OBD2 adapter and saw the code and also began monitoring the fuel pressure. It normally sits as between 52 and 56 psi but now when I accelerate and take my foot off the pedal and coast the FRP will climb to as high as 72-74 and then drop to 52 again.

Is this a vacuum leak or something else? The fuel pressure sensor is relatively new.

Thanks

 

[joegr]

That doesn't fit with what I would expect for a vacuum issue, but never say never. For sure I would carefully examine the three tube assembly that connects to the fuel pressure sensor and EGR. Those tubes get brittle and can crack where you don't easily see it. I've used a stethoscope to find a vacuum leak there before when I couldn't see the crack. Note that this maybe an electrical problem.

(I would expect a very brief fuel pressure surge when releasing the pedal right after acceleration.)

 

[rgorke]

That doesn't fit with what I would expect for a vacuum issue, but never say never. For sure I would carefully examine the three tube assembly that connects to the fuel pressure sensor and EGR. Those tubes get brittle and can crack where you don't easily see it. I've used a stethoscope to find a vacuum leak there before when I couldn't see the crack. Note that this maybe an electrical problem.

(I would expect a very brief fuel pressure surge when releasing the pedal right after acceleration.)

Thanks Joe!

Could you elaborate on the potential “electrical problem”? I will go through and clean and secure the connections.

Do you know the upper threshold for the fuel pressure to be too high? Is it 70psi or ?

 

[joegr]

Electrical problem would be (in this case) an intermittent open connection between the fuel pressure sensor and the PCM. It would include the fuel pressure connector, the wiring, and the PCM connector. It seems that the code could be complaining about the electrical signal or the actual pressure.
Sorry, I'm not sure exactly what momentary level is considered too high.

 

[rgorke]

I am bringing this back up because, well, it's back. I had swapped out different FPSs that I had and even bought a new Motorcraft sensor. As I monitor the fuel pressure during usual daily driving, it is 53-60 psi. The CEL and P0193 code has come on at the same location under similar conditions...after a long drive >50 miles, warm ambient temps >85 degrees, and at the same location going up a slight incline (at 65-75 mph) and then starting down (coasting) a decent 2 mile hill.

The fuel pressure goes up to 70 psi and gets stuck until I give the throttle a little push and then it comes back down. Could this be the throttle position sensor getting hot and sticking or something random like that?

 

[joegr]

...The fuel pressure goes up to 70 psi and gets stuck until I give the throttle a little push and then it comes back down. Could this be the throttle position sensor getting hot and sticking or something random like that?

70 seems higher than it should be, but I don't really know. I think that the pressure not changing while going down hill could be completely normal. When coasting, the PCM turns off the fuel injectors (and possibly even the fuel pump), so there is nothing to bleed off fuel pressure. When you push the gas pedal, it turns the injectors back on .
Of course, none of this really helps with your issue.

I would strongly suspect that any issue with the TPS on your gen 2 would result in ETC failsafe.

 

[jerryg2112]

The CEL and P0193 code has come on at the same location under similar conditions...after a long drive >50 miles, warm ambient temps >85 degrees, and at the same location going up a slight incline (at 65-75 mph) and then starting down (coasting) a decent 2 mile hill.

Are you resetting the CEL? If so maybe this isn't the condition that is triggering the code but the final emission drive cycle completing and then the pending code is set.