What about fuel pressure fo 99 Taurus 3.0????

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Moses - 20 Dec 2008 20:39 GMT

My obd still indicates lean fuel mixture so I tested fuel pressure.
After pressure was released and key turned on the pressure was 20lbs.
After starting the engine the pressure rose to 31 lbs. Then, on
removing vacuum from the pressure regulator, the pressure rose to 40.
Now, I think these readings should be OK and not require a new fuel
pump.
What role does the gas cap play? I note the testing instructions call
for removing the gas cap prior to the pressure test.

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mechanic@telusplanet.net - 20 Dec 2008 21:12 GMT

Testing fuel pressure at idle is a fools errand... it desparately needs to
be tested when demands on the fuel system are at their highest - while
driving under high throttle requests...

FWIW. many things can drive fuel mixtures lean.... dirty MAF sensor, exhaust
leaks, low fuel pressure (this will be a transient condition), fuel
quality,...

Was there any freeze frame data with your codes?

> My obd still indicates lean fuel mixture so I tested fuel pressure.
> After pressure was released and key turned on the pressure was 20lbs.
[quoted text clipped - 4 lines]
> What role does the gas cap play? I note the testing instructions call
> for removing the gas cap prior to the pressure test.

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Moses - 21 Dec 2008 01:16 GMT

> Testing fuel pressure at idle is a fools errand... it desparately needs to
> be tested when demands on the fuel system are at their highest - while
[quoted text clipped - 5 lines]
>
> Was there any freeze frame data with your codes?

I'm not equiped to get freeze frame data, but the 171 and 174 codes
always come on the second time the engine starts. I took a chance on
replacing the idle speed control too.
MAF sensor was cleaned and then swapped out with no improvment. Also
replaced the dpfe and tuned the car with plugs, filter. Should be no
problems with EGR. Manifold vacuum reads 14.5

> > My obd still indicates lean fuel mixture so I tested fuel pressure.
> > After pressure was released and key turned on the pressure was 20lbs.
> > After starting the engine the pressure rose to 31 lbs. Then, on
> > removing

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Chevy - 22 Dec 2008 23:09 GMT

14.5 inches of vacume seams low to me ..if it was a 2.2 L dodge..then id
say its doing good , but this 3.0 liter should be much higher ..16.5 - 17
or more ...id be looking for a vacume leak ....EGR stuck slightly open ...
bad pcv valve ,
idle engine , spray some air intake cleaner around intake to head gaskets ,
on all vacume hoses , around injector seals ..see if this makes the idle
change , throttle body to manifold gasket ,
what is O2 sensor reading at idle when light comes on ...and compair it to
injector pulse .width ....what is scan tool reading for injector on time ?
if O2 reading is low and injector on time is high , o2 could be fixed lean
, this being a 1999 you should have two O2s one on each bank left and right
...compair scan tool reading for them , if one is rich and other lean id
look for vacume leaks or try swaping o2s ,, if prob switches sides , then
id say one o2 sensor if pooched ...

> Testing fuel pressure at idle is a fools errand... it desparately needs to
> be tested when demands on the fuel system are at their highest - while
[quoted text clipped - 6 lines]
>
> Was there any freeze frame data with your codes?

> "Moses" <awel...@wi.rr.com> wrote in message
>
[quoted text clipped - 4 lines]
> > After starting the engine the pressure rose to 31 lbs. Then, on
> > removing

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