Fuel Pressure Regulator

[FloridaGrown]

Hey guys,
I just bought this truck a week or so ago and I'm having some symptoms that lead me to believe that the regulator is going out. If I let the truck sit 5 minutes or more the truck will hard start. There's a slight hesitation from when the starter turns the motor over to when it will actually start. 2 or 3 seconds. Also, when the truck starts it stumbles for about a second or I have to crank it again to get it to start. I haven't done a tune up yet or pulled plugs. But these symptoms spell FPR. I'm thinking the rubber diaphragm in the regulator is ripped or worn to the point that it's letting the fuel leak back into the tank rather then keeping it in the injectors and fuel rail. so it takes longer for the fuel pump to push the fuel into the injectors. The stumble it has is probably from it not having enough fuel so it's going to struggle to run until the proper amount of fuel pressure is built up so it can run correctly. Can ignition components cause these symptoms also? How do i check if there's the proper amount of fuel in the lines? I realize a FPT but can you explain how to diagnose a faulty FPR ? thanks Aaron

 

[FloridaGrown]

Come on 5 people and no opinions? Come on guys!

 

[RonD]

2000 Ranger won't have an FPR, it has a Pulse Damper, either can leak fuel into the intake via the attached vacuum line, remove this line and check for fuel or fuel smell.

Ford computers Prime the fuel system for 2 seconds each time key is turned on.
So turn key on, count to 3 then turn key off, repeat this 3 times, then try to start engine, if it starts right up then the Check Valve(back flow preventer) in the fuel pump is failing, OR......you may have a leaking fuel injector.

Turn key on(just once)
Press gas pedal to the floor and hold it there
Try to start engine, leaving gas pedal to the floor

Engine should not start or even fire
The above turns off the fuel injectors, but leaves spark on, it is called "clear flooded engine mode", all EFI engine have this.

If engine fires with gas pedal to the floor then fuel has leaked in

 

[FloridaGrown]

Okay I'm going to see if I have a leaky injector now. To be sure can't I buy some of that UV dye and add it to my fuel? If there's a lot of fuel (dye) in my oil that would indicate a leaky injector. I realize a little fuel gets past the rings but a lot of fuel should make it 100%. what's the difference between a pulse dampner and a FPR? Can you explain? How it functions? Thanks Aaron

 

[FloridaGrown]

I did the test and the truck didn't start.
Alright, pulse dampner is next. Thanks I feel relieved the injectors don't leak. I'll do the v as live test tomorrow.

 

[RonD]

I believe it was the 1998 model year that Rangers were switched to a Returnless fuel system.
Prior to that year there was an FPR on the fuel rail that was connected to the fuel pump line the fuel rail line and the return line.
When engine vacuum was high(idle) the FPR would be pulled open and fuel would be sent to the return line and back to the fuel tank, as engine vacuum decreased the FPR would close a bit and less fuel was sent back to the tank.
This system maintained a 30-40psi at the injectors, while engine was running the fuel pump was on.

In '98 and up they use a 70psi fuel pump to maintain 60-70psi at the injectors, the return line was eliminated, so no FPR.
But at that pressure the injectors opening and closing will create pulses in the fuel rail, these pulse waves can cause more and less fuel to flow out an injector, so a Pulse Damper was added, this basically absorbs pulses as name says.
It has a vacuum line attached only for safety reasons, if it diagram leaked fuel would spray out and down to the exhaust pipes.
Computer has the ability to shut off fuel pump while engine is running, based on throttle position and calculated fuel use.

 

[FloridaGrown]

Okay, so i'm assuming it's the only thing that's vacuum related that is attached to the fuel rail. alright. I'll pull the vacuum line off tomorrow and see if fuels in there. Thank you for the explanation. I'll keep you updated. I'm going to do do a tune up and replace the coil pack for past reasons. If fuel comes out of that hose it will be replaced immediately. Obviously, for safety reasons. I'll let you know tomorrow. Thanks, Aaron.

 

[RonD]

If "clear flooded engine" test was OK, no start/no fire, then Pulse Damper isn't leaking

 

[FloridaGrown]

Well I'm going to buy a FPT and check the fuel pressure after the motors been shut off. See what it's at. If that checks out It's got to be some kind of synchronizing sensor. Or worn ignition components. As I said before I'll let you know.

 

[FloridaGrown]

So I did a series of tests today and I think it's the valve in the fuel pump. I went to start it this morning and it hard started. I drove it to work let it sit until about noon roughly 4 hours. I cycled the key twice from off to the run position without engaging the starter and it started right up. So my next thing to do is to start spraying bed mount bolts. Anyone know the size/kind of bolt? I.E Torx? Another thing. Would it hurt anything to cycle the key over in the morning to conserve battery life. Also, to keep my ranger from sounding like a P.O.S. Thanks Aaron. As usual, I'll keep you updated.

 

[TxGasRacer]

I just went through this with my 1998 Ranger and the bed bolts are 55 Torx head bolts and I used a two foot long breaker bar 3/4 drive with a 1/2 drive reducer and the Torx 55 bit and took all six of the bed bolts right out No problem.Dont forget about the three small screws that hold in the gas filler neck and then undo the electricl connecter in the back near the bumper and you are on your way.