Check valve or regulator may be out but now engine idles great

oachs83 · May 26, 2015

2002 Ranger 3.0 OHV Gas with 289,xxx on it. So I am the second owner of this pickup and bought it with a bad valve in the head. It was cheaper and wiser to throw a Taurus motor in it that had only 57k on the engine when the truck already had 195k on it. The truck has always had a rough idle, nothing bad at all but you could feel it in your seat and steering wheel. Through my ownership of the truck I have changed head gaskets twice in the truck, put on a new air bypass valve, IAC and changed plugs about 20k miles ago as well as a coil pack, just replaced the battery two weeks ago, and still the idle has never snapped out of it. Today I go to start my truck and it cranked over forever to start. It did it again after sitting about two hours. I soon think it may be a fuel pressure regulator but not positive. I also am curious if these fuel pumps have a check valve in it or does the regulator hold the pressure? Either way the funny thing is the truck now idles very smooth. I can hardly feel anything on the steering wheel. I don't think it is a coincidence this happened and whatever seems to be causing my hard starting also seem to help my rough idle.

My questions to you guys are:

1. Have you ever came across this problem with the idle issue like I have?

2. Will the fuel pressure regulator on the 3.0 engine cause the hard starting?

3. The plugs have 20k + miles on them should i start there?

4. Do signs point to fuel pump (is there a check valve in these)?

Like I said if I prime it with the key a couple times before I start it it fires just fine. Once started the truck runs as it should. Thanks in advance for the help. :headbang:

RonD · May 26, 2015

In the late 1990's Ford changed to a returnless fuel system, so the Fuel Pressure regulator was no longer used, it was on the Return fuel line.

Some Ford trucks with returnless systems used an FPDM(fuel pump demand module), not sure if the Rangers did?
With returnless systems the computer(PCM) calculates fuel demand and cycles the fuel pump on and off to maintain 65psi fuel pressure at the injectors.

Yes, the fuel pump has a check valve.
And yes they do fail and you will lose fuel pressure after engine is shut off.

There is also a Pulse Damper at the end of the fuel rail, it will have a vacuum hose attached, check that hose for fuel or fuel smell, replace it if there is fuel in that hose.
The Damper diaphragm prevents pressure waves from being amplified as injectors open and close, and it can leak, the vacuum hose is there to prevent a leak from starting a fire.

I would check for a leaking injector.
With engine warmed up shut it off.
Turn key on
Press gas pedal to the floor and hold it down all the way, this tells computer to turn off fuel injectors, it is called "Clear Flooded Engine mode"
In your case turn key off and on a few times to get Prime pressure, but leave gas pedal down all the way.
Now crank engine
It should NOT start, it should not even fire, there should be no fuel getting into the intake with fuel injectors shut off.
If it fires even a little then you do have a leaking injector and that could cause a low RPM misfire, and of course, loss of pressure when engine is off.
When you release the gas pedal the fuel injectors will start working again.

If you think you do have a leaking injector then the above test can help you find it.
Disable spark, unplugging coil will work.
Do the above test, crank it a few times with gas pedal to the floor.
Now remove the spark plugs, one at a time, when you find the wet one you found the leaking injector.

oachs83 · May 26, 2015

Ron, really awesome advice. Thanks so much I will give that a try.

JP02XLT · May 26, 2015

The Ranger does have a regulator on it, it is in the pump housing in the tank, It works the same as the return line systems, except the excess fuel now never leaves the tank as the regulator dumps the excess into the tank. The regulators can go bad, but generally you see diminished performance as they tend to open and drop FP, which can also lead to hard starting as well, but generally a hard start like was mentioned is the check valve. Good luck finding a regulator, no one had them separately when mine started to go bad, they all wanted to sell you the entire pump cartridge assembly. Since I had replaced the pump with a larger unit I had to get creative with the repair to the regulator, I grafted an after market unit into the stock housing and now had an adjustable regulator instead of the stock fixed unit.

JP02XLT

oachs83 · May 27, 2015

Okay, I tried the pedal to the floor trick and it does not attempt to fire at all so I think I may be fine with the injectors. If it is the check valve is that a sign of the pump going South or if I am fine with starting it by priming it for now I should be okay?

RonD · May 27, 2015

No crystal ball here

Pump could run fine for 13 more years, or could quit today.
Not sure on any data for failing check valve and pump longevity.

And it might not even be the check valve, could be a leaking hose in the tank.
Usually the check valve is on the outlet of the pump, part of the pump, and then there is a hose up to the access plate, if that hose leaks it would show the same symptoms.
And leak could get worse, you would notice that as lack of power or bucking at higher demand, higher speed.

enjr44 · May 27, 2015

My leaking check valve lasted about 18 months and then the pump died. Just would not start one day.

But, the real worry is when/where it will die. Lucky for me it died in the driveway. But, a 100 or 150 towing bill goes a long way toward the cost of the pump assembly.

oachs83 · Jun 8, 2015

UPDATE: So up until last week I have had to turn the key to prime the pump three times and the truck would fire right up every time until about a week ago. It stumbled very hard and struggled bad to start and finally started and I now had a engine light on. I checked it with my code reader and it said that I had a camshaft position sensor code and that was it. Hoping it was not the whole synchro I went with the $28 camshaft sensor. BAM! The truck fires up every time the first time. Also I used to have this problem with it going to a high idle now and then and at times would idle high enough it would feel like it was pushing me as I would come to stops. I replaced the IAC as well as the throttle position sensor in the past and it never seemed to help the problem. That problem was very erratic. Now a week has gone by and the truck runs better than I have ever had it run. The idle is great and no longer slightly rough. The idle does not rise anymore and it starts right up every time on the first try. It was just very strange that I had to prime the system like it was a fuel delivery problem. Oh well hopefully closed the book on this issue.

Check valve or regulator may be out but now engine idles great

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