Ok, I put a new fpr on 5.0 and still have 64 psi at rail. last time I checked the pressure it was about 35 or so. does pump in tank hav a separate reg that can push too much fuel ? its the 3.0 tank and pump. the 5.0 pump bolts to tank, mine has a ring that turns off according to sites and my book on truck. unless there is a way to change something from pump to pump if u get what I'm saying, its a conversion..5.0 swap..so maybe I need to put something from 5.0 on my pump. I still have the old tank and 5.0 pump is in garage.

 

1998 and up Rangers used Returnless Fuel system, no FPR, so used 65psi fuel pressure
1997 and older used Return style with FPR on fuel rail, they used 35psi pressure

1997 or older Ranger fuel pump could produce 65psi if FPR didn't open at all
FPR spring should be pushed open at 42-45psi, and with engine running and vacuum hose attached to FPR you should see 30-40psi at the rail

Newer Rangers with Returnless used Duty cycle calculator in the computer to turn fuel pump on and off depending on calculated fuel use.
There was a fuel pressure monitor added to the gas tank in later years, not sure what year that was first used, maybe 2003 and up??
It wasn't an FPR, no valve and spring, it was a fuel pressure sensor so computer would turn power to fuel pump off and on, to maintain correct pressure, took the place of duty cycle calculator

 

Yes I have a 97 5.0 with return fuel that had 35-40 psi, the fuel pump runs at 60 or higher for the 3.0 that was in it. I put a new pfr on and I'm still at 64 psi. she runs ok then she will run a bit crappy, maybe getting loaded up or something. I'm just wondering if the pump has the regulator and its pushing more than it should. I read a few forums where guys said they had to do some altering of their fuel pumps?

 

It is one heck of a fuel pump then, if it can maintain 60+ psi with FPR fully opened.

I would do this
COLD ENGINE
Relieve pressure in fuel rail, and install fuel pressure gauge
Remove return line from FPR
Put a towel down under FPR
Turn key on, count to 3, then turn it off, fuel pump will run for 2 seconds, that should add about 10-15psi to gauge
Repeat key on and off, should be up to about 25-30psi

Repeat key on/off again, at 40-45psi fuel should start coming out the FPR's Return hose connection.
If not you have the broken or incorrect FPR

Worst case is you get a new Fuel pump for 1997 or older Ranger

 

Lol, ya that's one way to look at it. u say remove return line from fpr..not sure wat u mean. I do get what ur saying...about testing fuel pressure but only turning key to on and not starting to see if pressure builds up. if it fails test get a 97 ranger pump because it will run at lower pressure...thanks, good idea.

 

There should be 2 fuel lines in the engine bay, they are nylon with metal mesh on the outside.
One comes from the fuel filter it is the IN line that connects to the fuel Rail, it has the pressure.

Second one is the OUT/Return fuel line, it runs back to the gas tank, this one is connected to the FPR
FPR also has a vacuum hose attached
Remove this Return line from the FPR.

 

Ok, I gotcha, I didn't realise the line fpr is connected to is return line. my bet is I will be putting a 97 ranger fuel pump in my 98. thanks for the help

 

You are describing Electronic Returnless Fuel as used on some Fords. However, 1998+ NA Rangers used Mechanical Returnless Fuel.

In the 98+ MRF system, the PCM turns the fuel pump on by applying battery voltage via the fuel relay but the PCM cannot regulate pressure. Pressure is controlled to a near constant value by means of a fuel pressure regulator inside the tank on the fuel pump module. The pressure regulation is accomplished by bleeding excess fuel back through a line from the third port on the fuel filter, through the regulator and then dumping it back into the tank fuel. Pressure is a constant 64 PSI +/- except for some Flex Fuel models that regulate to 55 PSI +/-.

The Ranger's Fuel Pressure Transducer is used by the PCM to monitor tank vapor pressure for the Evap System Leak Check Monitor. It has no effect on liquid fuel pressure.

 

Ok thanks, I had my fuel return line going to a duel inlet fuel filter, it was going to filler neck but tha has a tiny leak so I switched it. a mech at work told me he didn't like my new setup so I switched it back to filler neck and pressure is now back to 35 psi

 

If you wanted to use the port on top of the 98 fuel tank module for a fuel return line from the engine bay regulator, you would need to bypass the 64 PSI regulator inside the tank. Then find a compatible 2-port (single inlet, single outlet) fuel filter for the fuel supply line.

 

Ok, see the mechanic at work said they didn't put a regulator in tank ..but it's gotta b somewhere. I'm back at the filler neck and pressure is back at 35 psi

 

So I decided that I didn't like the leaks at back of factory cats. so they are gone...straight pipe in their place for now. probable a/m cats then who knows..maybe some headers down the road. she seems to idle better, definetly a bit louder now, lol, she doesn't have as much hesitation now. took her 2 trips around block, second pass hit her some and she did ok. one thing is for sure....if I'm ever under her again and trying to hold something heavy again above my face..floor jack time. the one tail pipe was tight to go up to hanger, slipped off elbow, busted me in the nose...never had that much blood come outta my nose b4...lol. I can laugh now but I wasn't earlier

 

I tried to hook up vac tester to 95 Saturn, couldn't see a single spot to hook it to. I got an idea and I thought when I put the tester on the vacuum hose I had a t fitting so I could still have it hooked to vac tree, I instead hooked it to line by itself and ive got 18 in vacuum. someone told me to slowly rev motor, vac should stay at 18 or rise slightly. I did this and vac dropped slightly and id swear the pre cats are fighting motor. at least I do have good vacuum.

 

Ok, I took her for a drive figuring if she does ok she is good for 17 mile run to work. she did ok til I got to a red light and the idle jumped around some. I put her in neutral and she calmed down. first thing I'm thinking is iac valve..maybe. its less than a year old but that doesn't mean much. possible tps? she acted up for a bit, id start her up, put her in drive and she would stall. let her sit in idle for a minute, put her in drive...idled. efi is awesome when all the **** works right...one part goes, everything goes to pot..lol

 

Vacuum goes down when you let more air into the intake, i.e. open the throttle plate
It will then come back up as RPMs increase and demand for more air increases.

Vacuum pressure is the air the engine Wants but can't have, lol.

When you close the throttle plate vacuum will go high until RPMs(demand for more air) goes down

Its Supply and Demand, and it is the only control we have for a gasoline engine's RPM

If you add less fuel you get pinging not an RPM change, if you add more fuel you get black smoke and flooded engine not an RPM change
Air flow into the engine changes RPM

 

Ok, I took her to work today, she did ok except when I stopped at gas station she didn't want to run when I restarted her. I tried 3 times, on 3 try I revved her to maybe 4000 grand then held her at 2000 for a few seconds, she then idled on her own. this weekend plugs are coming out to see how they look. on trip home she did fine, and at house I restarted her and she idled fine and revved. tempermental lady..huh. just a quick question, if I may..i just got a h pipe from summit, should it go b4 cats, the ones I don't have yet, or after or does it matter

 

Won't matter as far as power, for sound they go farther back in the system

 

So I called a performance shop to see how much it might be to have them look at my 5.0 and maybe tune it. Guy said they charge $110.00 per hr and might take a day to just look at it. He asked some questions about engine...if it's efi , how it runs, who put it in, basic stuff. I told him pretty much all sensors are new, not motorcar ft but new. He said if I've got a running rich code only 2 things can cause this..02s or maf sensor. The 02s , I have changed 1, the. Others are old. The maf is one for a 2000 mountaineer 5.0, she starts up and idles nice. I can baby gas to go 60 on highway. If I hit it hard while sitting in park she will rev, if I'm in drive at almost any speed and hit it hard..she hesitates bad.

 

I would spend the $30-$50 for a Bluetooth OBD2 reader and $5 for the Torque App
Then get familiar with the sensor menus and readings
Have someone else drive while you watch the O2 sensors and MAF sensor, the readings are pretty straight forward
O2's vary from .1(lean) to .9v(rich), and quickly, .3-.4 is what computer tries for with the air/fuel mix

MAF is .7v(idle) to about 4v at WOT, but select Grams per second if available and with engine idling it should be very close to 5g/s, because it is a 5 liter engine.

Also check spark advance, spark advance should drop closer to 10 BTDC when accelerating, then go back up toward 20deg BTDC and more as RPMs catch up to throttle position.

Computer reacts to O2 sensor voltage, O2s are there for lower emissions and best MPG.
When you accelerate the O2 sensors are ignored for the most part because MPG is not considered at that time, same as at WOT

Computer does need to know the air temp and air flow to provide the best calculated air/fuel ratio for demand/load.

Computer is programmed for a 5 LITER engine, so already knows how much air it can gobble up at any given RPM, i.e. 5 LITERS of air at WOT
But MAF and air temp are needed to fine tune that "known" amount of air

 

I have a scanner tool, not the but it shows all live data as motor runs. I will look at that stuff. If an 02 is going bad it could be causing some of my issues. Lol, she started this morning, ran good, was taking my lady to work and she started acting up. I thought about going back to house and switching vehicles. I shur her off revved her up steady, let it go down easy, she idled and I drove to work

 

It would be odd for an O2 sensor to cause the described issues without setting a code.

Computer constantly varies fuel mix from Rich to Lean to keep Cat converters working, whether you have Cats or not.
And computer watches O2 voltage as it does this to see if they are working, i.e. switching voltage fast and correctly, for Rich or Lean.
Now an older O2 that has used up its chemicals will start to show overall lower voltage so "looks lean", computer will then run engine Richer than it needs to be but engine won't run poorly just slightly less MPG, this is why new O2 sensor with over 100k miles will pay for themselves in the long run, better MPG

Computer has a Rich limit of about 15%, if it starts having to go about 15% over calculated amount of fuel on a regular basis then it will set a code for that.
It will still add the fuel but let the driver know there is a problem

 

I put the h pipe on and she has deeper sound, more even sound. lil raspy when I first hit it because of straight pipes in place of cats. I drove it around block, felt good. then it started the lack of power thing briefly then got better? I hooked scanner tool up and maf reading at idle is around 6.5 to 7.5 roughly g/s ...spark advance is around 17 and goes up as I give it gas. the maf is from a 2000 mountaineer 5.0 and has worked better than any one I put on it. that's not to say its working perfect but all the other ones, she wouldn't idle when cold. this one she starts and idles nice.

 

MAF reads high if RPMs were 600, warm engine idle
Expected is about 5g/s, engine displacement 5.0l
If idle was 800-900rpm then 6.5-7.5 would be OK


Spark advance is done because the 14.7:1 air:fuel mix burns in a fix length of time(usually)
You want full explosive ignition of the air fuel mix to happen when piston is 10deg AFTER TDC(ATDC) so it has good leverage to push down on the crank to add power, earlier and less leverage, later and you lose some of the pressure of the explosive expansion in the larger area above piston so don't add as much power.

Spark ignites a small part of the air fuel mix and then that flame front spreads to all the mixture to get full explosive power, and that takes time, milliseconds but still takes time.
Spark advance is used because the pistons time from say 10deg BTDC(Before TDC) to 10deg ATDC changes with RPM.
So to get the full explosive power at 10deg ATDC you need to Advance the when the spark happens as RPMs increase, at 6,000rpm you may have to spark the mixture at 28deg BTDC to get full power at 10deg ATDC, because piston is move from 28deg BTDC to 10deg ATDC in the same time it moved from 10deg BTDC to 10deg ATDC at 600 RPM

Burn time is fixed, piston speed is not

BUT(big but), burn time is not really written in stone fixed, lol
A Richer mix burns faster, more fuel to spread the flame front

In the old carb days they used Centrifugal Advance and Vacuum Advance on the distributor to control spark advance.
Centrifugal Advance used two weights and springs in the distributor, the faster the rotor in the distributor spins the farther the weights were pushed away which Advanced the spark based on RPM only, which works fine unless you want quick throttle response.
Base Spark timing is done to set Centrifugal Advance, whether it is for weights in the distributor or TFI or Distributorless there is a Centrifugal Advance spark timing that is strictly based on RPM.
This is why you would disconnected Vacuum Advance or SPOUT on TFI to set Base Spark timing.
And why Crank Position(CKP) Sensor placement on distributorless systems is important, it sets Base Spark timing for RPM.

Vacuum Advance was added for quick throttle response
It was a crude Throttle Position Sensor(TPS), lol.
In a carb when you stepped on the gas pedal accelerator pump would squirt extra fuel in making a Rich mix, and throttle plate would open
Throttle plate opening also lowered vacuum at distributor retarding spark timing for the Richer, faster burning, fuel mix.
Base spark timing advances with RPM, the Vacuum Advance changes that timing to match fuel mix.

Computer sets fuel mix ratio so is in a very good position to know what spark advance to use based on RPM and throttle position, and fuel mix ratio

Spark should advance with RPMs, but if you press down on gas pedal quickly spark should not advance and maybe retard a bit to compensate for the richer mix and faster burn rate

 

The idle was about 800 rpm or so, I guess maf giving good reading. Checking more stuff, lol....got a good one for you...I recently had to put a dash cluster in her. I got one on ebay for a 99 ranger/explorer...its same dash as what was in it. when I got it I thought id have to recalibrate tach for v8 but it hit me that's done by moving a wire on one of the plugs that go to it..i think it was #7 or 8 pin goes to end which is open so I just had to unplug 3 connectors and shifter cable and done, or so I thought. the speedometer is good. all gauge work, the tach is off guaranteed. any thoughts on this?

 

Not from me, maybe someone else will see this, but should be some info on the net on what wires need to be changed, would have to be at least 2 wires, can't see 1 wire change doing it