Fuel Pressure Regulator
- Thread starter MrWilson
- Start date
m_maker
Dedicated LVC Member
I just did - sorry it was edited after you must've posted.
It's a quote from the SCT guys.
It's a quote from the SCT guys.
torquemonkey
Dedicated LVC Member
I had gotten this out of the Ford Technical Service Publication CD
Fuel Pump Module
The fuel pump module has the following characteristics:
l The assembly rests within an internal retainer on the bottom of the fuel tank.
l The pump is mounted with its inlet at the bottom of the reservoir. This design increases satisfactory pump operation during extreme vehicle maneuvers and steep vehicle attitudes with low fuel levels.
l It is capable of supplying 140 liters (29.0 gallons) of fuel per hour at a working pressure of 269.0 kPa (39 psi) on the 4.6L, 4V DOHC MFI @ 13.2 volts.
l It has an internal check valve to maintain pressure in the system after the ignition switch is turned to OFF.
l It also has an internal relief valve to provide overpressure protection in the event that the fuel flow becomes restricted (for example by a clogged fuel filter and base (9B072) or damaged fuel tube). Overpressure is limited to 850 kPa (123 psi), and reduced fuel flow will result if the pressure relief valve is activated.
l The module is protected at its inlet by a nylon pick-up screen. It filters dirt and contaminants which could plug or damage the internal fuel pump components. This screen allows passage of small quantities of water which may accumulate within the fuel tank reservoir.
The electrical system:
l has a fuel pump control relay controlled by the powertrain control module (PCM) (12A650), which provides power to the fuel pump module through an inertia fuel shutoff switch (IFS switch) (9341), which is normally closed.
l provides power to the fuel pump module using:
— PCM power relay signal from the variable control relay module.
— high speed fuel pump relay.
The current path is dependent upon the operating conditions.
When starting or when engine fuel demands are high, the fuel pump module electrical supply will be at system voltage. At other times, voltage will be reduced.
l When the ignition switch is in the OFF position the contacts of both relays are open.
l When the ignition switch is first turned to the RUN position:
— the powertrain control module (PCM) power relay is energized, closing its contacts.
— power is provided to both the fuel pump relay and to a timing device in the powertrain control module.
— the fuel pump (9350) runs through the contacts of the fuel pump relay.
l If the ignition switch is not turned to the START position:
— the timing device in the powertrain control module will open the ground Circuit 57 (after approximately one second). Opening the ground circuit de-energizes the fuel pump relay, opening its contacts, which in turn de-energizes the fuel pump. This circuitry provides for pre-pressurization of the fuel system.
l When the ignition switch is turned to the START position:
— the powertrain control module operates the fuel pump relay to provide fuel while cranking.
l After the engine starts and the ignition switch is returned to the RUN position:
— power to the fuel pump is again supplied through the fuel pump relay.
— the powertrain control module senses engine speed and shuts off the fuel pump by opening the ground circuit to the fuel pump relay when the engine is below 120 rpm or the engine stops.
The fuel pressure regulator (9C968):
l is attached to the fuel injection supply manifold (9F792) downstream of the fuel injectors (9F593).
l regulates the fuel pressure supplied to the fuel injectors.
l is a diaphragm-operated relief valve in which one side of the diaphragm senses fuel pressure and the other side is subjected to intake manifold vacuum.
— nominal fuel pressure is established by a spring preload applied to the diaphragm.
l balances one side of the diaphragm with manifold pressure to maintain a constant fuel pressure drop across the fuel injectors.
l bypasses and returns excess fuel to the fuel tank.
For fuel pressure regulator service procedures; refer to «Section 303-04».
Fuel Pump Module
The fuel pump module has the following characteristics:
l The assembly rests within an internal retainer on the bottom of the fuel tank.
l The pump is mounted with its inlet at the bottom of the reservoir. This design increases satisfactory pump operation during extreme vehicle maneuvers and steep vehicle attitudes with low fuel levels.
l It is capable of supplying 140 liters (29.0 gallons) of fuel per hour at a working pressure of 269.0 kPa (39 psi) on the 4.6L, 4V DOHC MFI @ 13.2 volts.
l It has an internal check valve to maintain pressure in the system after the ignition switch is turned to OFF.
l It also has an internal relief valve to provide overpressure protection in the event that the fuel flow becomes restricted (for example by a clogged fuel filter and base (9B072) or damaged fuel tube). Overpressure is limited to 850 kPa (123 psi), and reduced fuel flow will result if the pressure relief valve is activated.
l The module is protected at its inlet by a nylon pick-up screen. It filters dirt and contaminants which could plug or damage the internal fuel pump components. This screen allows passage of small quantities of water which may accumulate within the fuel tank reservoir.
The electrical system:
l has a fuel pump control relay controlled by the powertrain control module (PCM) (12A650), which provides power to the fuel pump module through an inertia fuel shutoff switch (IFS switch) (9341), which is normally closed.
l provides power to the fuel pump module using:
— PCM power relay signal from the variable control relay module.
— high speed fuel pump relay.
The current path is dependent upon the operating conditions.
When starting or when engine fuel demands are high, the fuel pump module electrical supply will be at system voltage. At other times, voltage will be reduced.
l When the ignition switch is in the OFF position the contacts of both relays are open.
l When the ignition switch is first turned to the RUN position:
— the powertrain control module (PCM) power relay is energized, closing its contacts.
— power is provided to both the fuel pump relay and to a timing device in the powertrain control module.
— the fuel pump (9350) runs through the contacts of the fuel pump relay.
l If the ignition switch is not turned to the START position:
— the timing device in the powertrain control module will open the ground Circuit 57 (after approximately one second). Opening the ground circuit de-energizes the fuel pump relay, opening its contacts, which in turn de-energizes the fuel pump. This circuitry provides for pre-pressurization of the fuel system.
l When the ignition switch is turned to the START position:
— the powertrain control module operates the fuel pump relay to provide fuel while cranking.
l After the engine starts and the ignition switch is returned to the RUN position:
— power to the fuel pump is again supplied through the fuel pump relay.
— the powertrain control module senses engine speed and shuts off the fuel pump by opening the ground circuit to the fuel pump relay when the engine is below 120 rpm or the engine stops.
The fuel pressure regulator (9C968):
l is attached to the fuel injection supply manifold (9F792) downstream of the fuel injectors (9F593).
l regulates the fuel pressure supplied to the fuel injectors.
l is a diaphragm-operated relief valve in which one side of the diaphragm senses fuel pressure and the other side is subjected to intake manifold vacuum.
— nominal fuel pressure is established by a spring preload applied to the diaphragm.
l balances one side of the diaphragm with manifold pressure to maintain a constant fuel pressure drop across the fuel injectors.
l bypasses and returns excess fuel to the fuel tank.
For fuel pressure regulator service procedures; refer to «Section 303-04».
torquemonkey
Dedicated LVC Member
No problem, good discussion.
02LSE96LSC91SE84TC
Dedicated LVC Member
Agreed, good stuff.
94m5
Dmaup's Daddy
damm good info. and shows what a little communcation will accomplish. thanks for the info. wil store it in this old brain. JDS 353.
Sergmark
Dedicated LVC Member
Yes I agree, very informative.
I do have a walboro 255 and the Kirban regulator and have had no issues, I set the pressure at the recomended pressure maybe 30 or 40 I forget.Thanks for the info
I do have a walboro 255 and the Kirban regulator and have had no issues, I set the pressure at the recomended pressure maybe 30 or 40 I forget.Thanks for the info
AbrahamLincoln
Dedicated LVC Member
kirban's twenty minutes from my house 
love those grand nationals baby
love those grand nationals baby
dRock95MarkVIII
Well-Known LVC Member
255lph is WAY overkill for most of you, I think that's why you gen1 guys eat up the stock regulators (as the engine can't use all that extra fuel, it all has to be returned back)
Not too mention you are trying to return all that excessive fuel through the regulator to the much smaller tank return line. This causes the rail pressure to spike, taxing the regulator and throwing off the AFR as the injector duty cycle is not calculated for pressure that high. The PCM will make minor adjustments to the injector pulse to correct the AFR via o2 sensor reading, but with no fuel pressure sensor input to PCM it's still not the way to do things IMO
190lph would be a much better choice IMO, unless you are boosting it :biggrin:
Though, experience>speculation. If 255 is what works for you guys, do it!
Not too mention you are trying to return all that excessive fuel through the regulator to the much smaller tank return line. This causes the rail pressure to spike, taxing the regulator and throwing off the AFR as the injector duty cycle is not calculated for pressure that high. The PCM will make minor adjustments to the injector pulse to correct the AFR via o2 sensor reading, but with no fuel pressure sensor input to PCM it's still not the way to do things IMO
190lph would be a much better choice IMO, unless you are boosting it :biggrin:
Though, experience>speculation. If 255 is what works for you guys, do it!
kustomizingkid
Dedicated LVC Member
It seems like everyone does the 255, and the 4.10's lol...
Sounds good to me.
If a good stock pump can supply 140 LPH, then 190 is more than enough. One would also think that a 255 would also be more demanding on the car's electrical system - for no good reason, as alot of fuel will be returned back. Likely noisier too.
AbrahamLincoln
Dedicated LVC Member
150 shot = 255
lincolnboy
Dedicated LVC Member
HEY MR WILSON. Good o mr wilson. Miss seeing his thousand post almosy like Laser and his biljion post.
MediumD
Dedicated LVC Member
lotsa bad info all together in this thread...geno included
if you crank up the fuel pressure the PCM has NO WAY to turn it back down.
BUT.. at a particular injector pulsewidth the PCM knows what the AF should be.
Cranking up the fuel pressure squirts more fuel thru the same small opening, thus causing the fuel trims to come into play.
Since the PCM cannot control fuel pressure, it does its best to correct the rich condition in the only way possible.. by decreasing the injector pulsewidth.
If you datalog injector pulsewidth you can plainly see this occur.
OF course on Geno's first gen, he's as blind as hellen keller in regards to datalogging.
Just ask any second gen and it will tell you in a heartbeat that cranking up fuel pressure is the ABSOLUTE best way to screw up a good PCM calibration.
short term and long term fuel trims dont lie... even if adj FPR manufactuers and resellers do.
and it's also red white a blue BULLCRAP that a 255 pump will hurt a OEM fuel pressure regulator
i ran the oem regulator for almost 400K, 300K were with a 255 pump.
it didn't even hurt a 100K mile FPR..
hoisting the bs flag up another notch or two
i ran the oem regulator for almost 400K, 300K were with a 255 pump.
it didn't even hurt a 100K mile FPR..
hoisting the bs flag up another notch or two
MediumD
Dedicated LVC Member
I guess we as a community have learned some things in the 4 years since this thread was made.
