After 3 months FINALLY resolved!! :) :)
Started trying to use the AC and it wouldn't switch from defrost.. Did some
checking and wasn't getting any vacuum inside to the AC switch. Traced it
back and found alot of fuel in the vacuum hoses. Turned out the Fuel
Pressure Regulator was dumping pressurized fuel directly into the vacuum
system.
I'm still shocked it was running "normally" even with the fuel being forced
through the vacuum system, all with no fault codes and passing an emission
test...
Starts good, and the AC now switches normally.... Fixing 2 seemingly
unrelated issues in 30 minutes... priceless!!
Can anyone explain WHY vacuum is even needed on the FPR?
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Hi...
I have a 1998 Ford Windstar, 3.8, with about 102K miles. I have
disassembled and cleaning everything such as the TPS, ISC, PCV, etc and
still having issues.
Symptoms.
- Cold Engine - Starts easily, runs fine.
- Warm - Shut off and if started immediately, starts and runs fine.
- Warm - Shut off for 10 minutes and restarts, runs rough for 10-15
seconds,
then runs fine.
- Warm - Shut off for 30 minutes, Cranks for 10-15 seconds before
restarting, runs rough for a few seconds, then runs fine.
Shut it off for an hour and it starts perfectly!
Any clues where I should start looking?
> I just went thru a round similar to that with my F150. Fuel
mileage down and HC reading at high end of specs. Gave it a
tuneup that it was due for with no good results. Replaced
the O2 sensor with no help. No codes in ECM. Started going
thru system by the book checking reading against specs on
each sensor. The ECT was found about 30% higher impedance
than expected at several temperatures. Replaced it and
reset to ECM. HC reading dropped, fuel mileage up , hard
start and roughness corrected. May not be your problem but,
sometimes, you just have to get down to the bare elements to
find it. A good alternative for what I did is get your
dealer to run a complete diagnostic on it. These type
things seem to be found by the Ford test equipment. You '98
year model also has much more info available to isolate the
problem. The diagnostic cost is usually about an hour's
labor which is applied toward the repair if you choose to go
ahead with repair. In the long run, a good service tech can
save you money. If your problem is resulting in an over
rich fuel condition, the converter can easily be damaged
which can cost a bundle and you still have to get it
repaired. Then again, you could just put in a new ECT
sensor and and hope to get lucky the first time.
Repairman - 24 Jun 2009 12:46 GMT
> After 3 months FINALLY resolved!! :) :)
>
[quoted text clipped - 14 lines]
>
> ==========================================
FPR lowers injector pressure at idle and part throttle. Lower fuel needs.
Vacuum give a instant raise to supply pressure to meet wide open fuel needs.
Pressure variances allow injectors to meet a broader supply range from idle
to WOT with a single sized injector so
they can meet the occasional WOT needs without having to use secondary
injectors just for WOT demands.
James Patterson - 26 Jun 2009 15:24 GMT
>> Can anyone explain WHY vacuum is even needed on the FPR?
>>
[quoted text clipped - 6 lines]
> they can meet the occasional WOT needs without having to use secondary
> injectors just for WOT demands.
Thanks for the information. I assume that the ECM also varies the pulse
lenght at the FI combine with the change in pressure with to regulate how
much fuel is delivered.
Is there a sensor so the ECM is "aware" of the fuel pressure? Wouldn't
this be needed so the ECM can deliver the proper fuel ammount?
Sorry if I'm asking too much basic stuff here.....
Repairman - 27 Jun 2009 13:08 GMT
> Thanks for the information. I assume that the ECM also varies the pulse
> lenght at the FI combine with the change in pressure with to regulate how
> much fuel is delivered.
Yes
> Is there a sensor so the ECM is "aware" of the fuel pressure? Wouldn't
> this be needed so the ECM can deliver the proper fuel ammount?
I have not seen a fuel rail pressure sensor myself, just a
long time shade tree guy, but it's possible.
Vacuum mech. regulator is a cheaper non electrical way to vary fuel
pressure.
TPS and manifold pressure (MAP) are already monitored and figured into the
injector pulse rates .
Calibrated spring in the FPR for each size engine