Running Rich - ?'s about the FPR

[ranger7ltr]

After running rich for a while...

You may need to replace the plugs since they might be fouled with carbon...Getting some gas mileage back is a good sign though..Plus the extra fuel being burned MIGHT have caused a problem with the o2 sensors and the convertors...

Did you also check the voltage output of the ACT sensor as well? If there is carbon build-up in the exhaust it should clear out after a few hundred miles...

Actually these sensors shouldn't care what the adaptive memory has stored since each time the engine runs the parameters will change and the stored adaptive memory will change...But the adaptive memory is being relearned after pulling the battery cables and removing the battery voltage erases the Keep Alive Memory and you will need to drive it in various situations for the PCM to relearn your driving habits...

Drive the truck for a while and see if the conditions change over time...I would continue to use whatever fuel you normally use and drive like you would normally drive...

 

[clamb]

On all Ford trucks before model year 1999, the fuel system had a return line back to the tank, a fuel rail mounted vacuum controlled fuel pressure regulator, and an operating pressure in the range of 30-45 psi, 30 being the pressure at startup[System prime] and high vacuum conditions...

In model year 1999, Ford changed the trucks to a returnless fuel system which has no return line to the tank, no fuel rail mounted fuel pressure regulator, and an operating pressure in the 65-72 psi range...This systems pressure does not vary like the earlier system and there are 2 major differences here...First the fuel pressure regulator is still installed but is mounted on the fuel pump/sending unit assembly in the tank...The FPR is not vacuum controlled and it will bypass fuel from the fuel rail if the pressure gets over 80 psi...Second, there is a fuel damper mounted on the fuel rail which is there to smooth out the fuel pulsations before they enter the injectors...This unit is part of the fuel rail yst it will not vary the fuel pressure seen at the schrader valve...
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I just read another post & they described the black & silver valve on the fuel pump assembly a fuel damper or resonator. I removed my fuel pump assembly & found that it was leaking past the connections between the pump & the fuel pressure regulator in the tank. It was only building up to about 42 lbs pressure. After replacing the hoses & new clamps it would make 55 lbs. I thought I had my problem solved, but it appears that I should be pumping 65 psi. I used my air compressor to blow back into the tank & it seems like I can build up to about 75 psi before it bypasses the fuel pressure regulator. Is it possible to purchase the pump only as it appear that the fuel pressure regulator is fine? Thanks. Will my pressure increae if I run it off the truck system? I just tested it with an old 12 v battery sitting on the floor. Maybe my pressure will bew at the required 65 psi with the charging system putting out the full volts.

Calvin

 

[ranger7ltr]

The fuel damper is mounted on the fuel rail...

Not in the tank...The black and silver unit in the tank is the fuel pressure regulator which vents back into the tank...Look at the picture below for the black and silver unit on the tank mounted pump assembly...55 psi is on the low side of the requirements of the fuel pressure for the engine to run properly...If you run a pump without a regulator[as I have done], I can't tell you what the pressure will be... It will be sufficient to run the engine as I have plumbed in a seperate pump into the fuel line to move the truck from a remote area to my driveway so I can work on it...

As far as a pump is concerned, I replaced the Ford pump long ago with a Walbro unit...When I replaced the tank thanks to excessive rust the pump in the tank has lasted quite a while...I did have to replace the pump once after 3 months but that was a fluke problem with the pump and got it replaced and it has worked perfectly ever since...

 

[clamb]

UPDATE: I just reinstalled my old pump after tightening the in tank connections. I started it up & could tell there was an improvement already. After taking it out for a drive & topping it off with fuel, I tested the fuel pressure at the rail @ 64 lbs while running. But it doesn't seem to hold the pressure for more than a few seconds after shutting the vehicle off. When I last had it in at the shop for a checkup they said it was only building up about 40 lbs of pressure, & wouldn't hold. I will run a tank of fuel through it and see how it runs, I already have a replacement ordered for about $320.00, dealer wants about $580.00. Cancelled the new pump. I was watching the fuel pressure after shutting off a running vehicle, apparently I just need to cycle the key 2 or 3 times without starting, to buildup pressure, & it should hold pressure for 10-30 minutes. I haven't checked it again, but I am sure it is working properly.
When I tried to pressure up the fuel pump with an air compressor I couldn't get any air to bypass the check valve ball in the pump. When the Fuel pressure regulator is connected to the pump it will allow it to buildup to about 75 psi, & then it starts to bypass through the plastic spouting. With the fuel pressure regulator removed you can blow straight through from either end.

Wonder how many shops have changed fuel pumps needlessly.


I didn't remove the fuel presure regulator, I just reinstalled new EFI hose & new hose clamps. The factory clamps were just the crimp type, & they were leaking past. I was able to pull the bottom hose from the fuel pressure regulator to the pump without removing the clamps.

 

[Brandon96]

...

The cat rattle is just getting worse and worse, I think, with somewhere around 170k on them it's just their time to go.. lol I'm on the 2nd tank of regular, and the mileage just dropped off again to where it was.

The overwhelming fuel smell is still there, still especially noticeable just after startup. I am 90% sure fuel is getting into my intake somehow, I tore it all down while I was bored monday and found my upper intake is absolutely disgusting on the inside. I believe it should have had a smooth finish on the inside coming out of the factory, it now is completely covered in nasty carbon-like deposits and looks like it's being deteriorated by something acidic, the plastic otherwise is in great shape. The fuel smell was also extremely present while I was disassembling it.

I don't mean to argue the previous tests I did and anything that you've told me as your knowledge of this far exceeds mine, but I'd really like to take another look at the FPR, is it possible for this thing to be dumping fuel into the intake and for it to be undetectable upon visual inspection? I know there wasn't any fuel in the vacuum line, but I've also read it could do it only while the engine was warmed.

This thing is starting to drive me nuts!

The ACT sensor was throwing good voltage as well, and the scanguageII tells me the ACT is around +/- 2 degrees of the actual outside air as long as I'm moving, If I come to a stop it heats up a bit.

-Brandon

 

[Fireside3]

The cat rattle is just getting worse and worse, I think, with somewhere around 170k on them it's just their time to go.. lol I'm on the 2nd tank of regular, and the mileage just dropped off again to where it was.

The overwhelming fuel smell is still there, still especially noticeable just after startup. I am 90% sure fuel is getting into my intake somehow, I tore it all down while I was bored monday and found my upper intake is absolutely disgusting on the inside. I believe it should have had a smooth finish on the inside coming out of the factory, it now is completely covered in nasty carbon-like deposits and looks like it's being deteriorated by something acidic, the plastic otherwise is in great shape. The fuel smell was also extremely present while I was disassembling it.

I don't mean to argue the previous tests I did and anything that you've told me as your knowledge of this far exceeds mine, but I'd really like to take another look at the FPR, is it possible for this thing to be dumping fuel into the intake and for it to be undetectable upon visual inspection? I know there wasn't any fuel in the vacuum line, but I've also read it could do it only while the engine was warmed.

This thing is starting to drive me nuts!

The ACT sensor was throwing good voltage as well, and the scanguageII tells me the ACT is around +/- 2 degrees of the actual outside air as long as I'm moving, If I come to a stop it heats up a bit.

-Brandon

Hey, before you condemn the intake, I read a warning not to clean them, that those plastic intakes come from the factory that way with a special coating that traps debris so it does not enter the cylinders. It's supposed to accumulate that ****, but you may want to get a new one if it's really bad.

 

[Brandon96]

Guess who just got all their MPG's back!! Though it passed all the tests suggested to me by you, I could still smell fuel in the vacuum line and it ended up being the FPR. I spent $64.99 on a new BWD one yesterday and went about swapping the two out. Time crept up on me and before I knew it, it was time to get to class so hauled arse downtown!

I did a 25 mile trip @ 75+mph, shhhh.

And when I got there I peeked down at my scanguage to see this! I was impressed, wouldn't expect that with 33's and 4.10 gears!

Wooh!!! I want to thank you ranger7ltr, for all the great info, hopefully this helps some people in the future.

 

[ranger7ltr]

Excellent!!!!!

That is great news Brandon...Sometimes problems are obvious, sometimes not...The fuel smell but no liquid in the vacuum line to the FPR was strange but not obvious...And since the other sensors and tuning did not change the mileage, changing the fpr removed the problem that was not as obvious as, say, a clogged fuel filter...

Excellent investigative work though...That is what helps you learn more about the truck and the way it's running and the way it should be running...

Frankly I think most of the info on the board will assist others getting their trucks to run or look the way they want...

Thank you for logging the steps you did to get back to where it should be running for you...

 

[Kristy_Kai]

Can anyone help 1999 Explorer XL 4.0L OHC running rich

Hi to everyone on the forum,

Honestly hoped I would never have to be in this position but would love some help from all the wonderful members if your able.

Last weekend I replaced the Clutch and Slave on my 1999 Explorer XL. I didn't turn the flywheel much more than around and inch either way when doing this.

Now my truck runs stone cold according to the dash guage and when pulling up at lights she revs at 2k then slowly drops down to 750 before bouncing round and almost stalling. I have to use the gearbox to slow down the idle when I am pulling up to lights.

Also she is now using around 30 Ltrs to get approx 120km and when I shift down and put my foot on the juice she bogs down, and almost sounds like the injectors are cutting out, no power.

Freeway cruising she runs nice and smooth (still ice cold temp wise). Check Engine Light is on but not sure for what yet although in the past it has come on due to AC fault which is strange as there is nothing wrong with the AC. Have cleared that in the past and it has only come back once or twice with the same result.

I have had the Mechanic check out the thermostate and he said it isn't sticking open which seems like a good sign. There are no O2 Sensor faults coming up either.

Any help on this would be very much appreciated as I can't understand how something as simple as replacing a clutch can generate a random issue such as this. =(

Thanks all.

Cheers,

Kristy & Kai
Sydney Australia