Fuel Pump Dilemma! Help if you can?

[rickpotz]

Okay guys or gals, your diagnosis of what I'm about to describe is going to be fuel pump or fuel filter! I already know that.

What I don't know is why? I've had to change three fuel pumps in the less than 10,000 miles and now I'm about to do it again!

I have a fuel pressure reading at times of over 60 psi. If i just let the car run for a few minutes that 60 goes as low as 30 or 10 psi.

Oh, you should know that this is a 2000 explorer with about 87,000 miles on it. I just replaced this part about 3 months ago with a Ford fuel filter.

Sometimes when I start the car I can drive it for days other times the pressure drops. Often I can restart it and the problem goes away. Sometimes it won't.

What is frustrating is the number of times I have diagnosed the same problem yet after pump replacement the car runs fine for a few months and then the pump goes out again. The symptoms may change but the end result is the same: fuel pump replacement.

The fuel filter seemed good but I replaced it anyway.
I did have two codes but I didn't pay much attention to them due to the fuel pump readings. I think the codes were 174 and either 170 or 171.

I used a vacuum gauge on the pressure regulator value and gave it about 10 lbs of pressure- the diaphram holds! I'm not sure how much pressure it needs hold? My experience is that if the diaphram is bad it will lose pressure regardless. No signs of fuel in the vacuum hose either.

I'm not sure the pressure regulator value could boost the fuel pressure that much anyway.

Everything leads back to a bad fuel filter the question is why? What is making my fuel filters go bad? Like I said this is the fourth time.

I would appreciate some imput from some savy ford mechanics.

Tears-- I mean cheers!

 

[Willard]

Wait - are you using the terms Fuel Filter and Fuel pump interchangeably? Because they are most definitely two different things.

The question is now which one have you been replacing? The fuel filter would be on the frame rail with two fuel lines going into it, that's it. The fuel pump is mounted in the tank with a fuel line and wires going to it.

I'm going to assume you have been replacing the actual pump. First off, are you replacing JUST the pump, or the pump/sender assembly? If just the pump, are you putting a new strainer on there with it? If not this could cause the pump to fail prematurely.

Besides dirt getting into the pump, the only thing I can think of off hand that would cause one to fail so fast would be some sort of electrical issue frying the pump.

 

[rickpotz]

thank you for your reply.
I have replaced third fuel pumps.
I have also changed several fuel filters. Just as a precaution.
most of the time I have replaced the whole assembly. Once I replaced just the pump.

If it is some sort of electrical issue, how would I track it down?

 

[Willard]

Hmmm...well I would start looking for a bad ground first to see if you have something up there.

This is a tough one, hopefully someone slightly more knowledgeable can chime in.

 

[ranger7ltr]

A little more information please..

I am looking at your description and it lists a 2000 Explorer Sport;is that the vehicle you are working on?

If it is, is the engine an OHV or SOHC? If it is OHV, are you testing the device on the pass. side of the engine with your vacuum gauge? If so, that is a fuel pressure damper not the fuel pressure regulator... That model has the fuel pressure regulator mounted on the fuel sender in the tank...There is no vacuum involved in that unit...

I also believe that all Explorers from 99-newer were using the returnless fuel system which means the FPR will also be in the tank...

When you changed out the fuel pump/sending unit did you verify the length was the same as the original? I swapped a boneyard unit into my Sport and I did not verify the length being the same and I am going back with the original unit with a new pump on it...

Another question is I am going to assume that the fuel pressure you are measuring is with the truck stationary and you using a temporary gauge... Is this accurate? If it is, can you hear any changes in the fuel pump sound when the pressure drops?

My last question is does this problem occur with the tank full of fuel as well as when some fuel has been used as indicated by the fuel gauge? I have mounted an Autometer electric fuel pressure gauge to my 99 Sport due to wanting to see if I have the correct fuel pressure all the time while running.. I have seen delivery[or what I perceive as delivery] problems as the tank empties under hard acceleration...The engine will pull to 4-5k rpm then start a surge that will not quit until I back off the throttle to halfway or so.. Then the engine pulls fine and will accelerate to any speed; just not at or near full throttle...

 

[n0xdw]

Check the connections to the pump for burned terminals. Check the terminals for tension. Like someone else said is it the OHC or the pushrod engine? I believe the OHC did not use a fuel pressure regulator as such bet rather controlled the pressure by controlling the current to the pump. If so you might check the pressure sensor. If it is the push rod engine there will be a regulator in the tank. I have service manuals for 99, and will assume they apply to 2000 as i know they made changes in 99 and likely would still be the same for more then one year.

 

[rickpotz]

I am looking at your description and it lists a 2000 Explorer Sport;is that the vehicle you are working on?

If it is, is the engine an OHV or SOHC? If it is OHV, are you testing the device on the pass. side of the engine with your vacuum gauge? If so, that is a fuel pressure damper not the fuel pressure regulator... That model has the fuel pressure regulator mounted on the fuel sender in the tank...There is no vacuum involved in that unit...

To be honest, I'm not sure whether this is a SOHC or OHV? My vin number is X for the engine type and that is what I'm using. The dealer told me it was a SOHC but usually they they that written on the engine. I don't see it anywhere. How can I make sure?

I also believe that all Explorers from 99-newer were using the returnless fuel system which means the FPR will also be in the tank...

It could be. From my Haynes book, it looks very similar to the fuel pressure regulator they show but it is on the passenger side of the engine at the front and it does have a heavy fuel line going to it with vaccum. How can I tell the difference between a damper and regulator?

When you changed out the fuel pump/sending unit did you verify the length was the same as the original? I swapped a boneyard unit into my Sport and I did not verify the length being the same and I am going back with the original unit with a new pump on it...

They looked the same. One was not shorter than the other! I'm assuming your thinking that I may have one that is too short? Unfortunately, I believe the pump has to come out so I will measure it just to make sure. I got this one directly from the dealer using my vin number so I would be surprised if it's the wrong length. But, it is possible. Parts dealers are wrong at times.

Another question is I am going to assume that the fuel pressure you are measuring is with the truck stationary and you using a temporary gauge... Is this accurate? If it is, can you hear any changes in the fuel pump sound when the pressure drops?

it is a temporary gauge. I haven't checked for a change in sound my pump is very quiet. When it is running I can barely hear it. I can check for noise change today. I'm about ready to go out work on it now. At the gauge there is no noise.

My last question is does this problem occur with the tank full of fuel as well as when some fuel has been used as indicated by the fuel gauge? I have mounted an Autometer electric fuel pressure gauge to my 99 Sport due to wanting to see if I have the correct fuel pressure all the time while running.. I have seen delivery[or what I perceive as delivery] problems as the tank empties under hard acceleration...The engine will pull to 4-5k rpm then start a surge that will not quit until I back off the throttle to halfway or so.. Then the engine pulls fine and will accelerate to any speed; just not at or near full throttle...

I'm pretty sure that the fuel tank level isn't an issue this time. The driveability is different than what you describe.
First, I can be at idle and lose pressure.
As I put my foot on the gas, the engine has no power. I can't speed up at all.
I can floor the gas pedal and the engine does nothing. I can usually idle but sometimes it will die.
I can stop the car, turn it off, and start it again and it will drive fine sometimes.

I drove about 20 miles with no problem. Then, I stopped at an auto store for a minute. Restarted the car and could barely drive on take off.

I can be driving at 30 or 40 miles an hour and the pressure drop will occur ( i know the pressure drops because I drive with the gauge connected) when the pressure drops I usually have to coast to a stop and restart the car. Sometimes it will surge and still drive but not often. Most of the time the problem occurs on take off.

I can sit at idle and rev the engine sky high and have a drop of 5 pounds or so. I can also have the car sit there at idle for 3 minutes and not touch the accelerator and suddenly the fuel pressure drops down to 30, 20 or 10 pounds and stays there.

One other thing, thanks for your comments.

 

[ranger7ltr]

Good info.. Thanks...

Using the vin code your engine is an OHV 4.0 liter...On the plastic upper intake it will have "4 liter EFI" molded into the casting...There will also be no cover on the intake at all...

The easiest way to tell that you have a returnless fuel injection system is the lack of a return line to the tank.. Also the fuel damper will only have a vacuum line to it and no return fuel line back to the tank... A fuel pressure regulator will have a vacuum line for regulation and a return fuel line to relieve the extra fuel volume and return it to the tank...

Yes your issues are very different from mine and the variance does seem like an electrical problem...

So I guess my next question is what is the condition of your alternator and the rest of the charging system? When this problem started was there any work/changes done to the truck right before? If you have a voltmeter i would check the output of the alternator to the battery and make sure the battery is not down on fluid, the connections are corrosion-free, and the wiring is sound throughout the truck...

Any blown fuses or motors/circuits/lights that don't work out of the blue?

This is starting to sound like a possible PCM issue...Especially after 4 pumps have been changed.. I really hope it is not...

 

[rickpotz]

Check the connections to the pump for burned terminals. Ok

Check the terminals for tension. When you say "Check for tension" I believe you are saying to make sure the connections are tight?

Like someone else said is it the OHC or the pushrod engine
I attached a three pictures so someone can help me identify my engine. One of the pictures is of the pressure regulator or damper. I would appreciate help in identifying this object also.

the OHC did not use a fuel pressure regulator as such bet rather controlled the pressure by controlling the current to the pump.
If so you might check the pressure sensor.


So, a pressure problem can be something other than the pump? I will check to see if I can locate a pressure sensor.

If it is the push rod engine there will be a regulator in the tank. I have service manuals for 99, and will assume they apply to 2000 as i know they made changes in 99 and likely would still be the same for more then one year.

This pump assembly is only two or three months old. It better not be the pressure regulator in the tank!


Thanks for you input.

 

[rickpotz]

This pump assembly is only two or three months old. It better not be the pressure regulator in the tank!


Thanks for you input.

 

[rickpotz]

Using the vin code your engine is an OHV 4.0 liter...On the plastic upper intake it will have "4 liter EFI" molded into the casting... I do have EFT molded into the plastic cover on top of my engine.
There will also be no cover on the intake at all...

The easiest way to tell that you have a returnless fuel injection system is the lack of a return line to the tank..
I have a return line on my fuel tank.

Also the fuel damper will only have a vacuum line to it and no return fuel line back to the tank... A fuel pressure regulator will have a vacuum line for regulation and a return fuel line to relieve the extra fuel volume and return it to the tank... I have a fuel line and a vacuum line on the part to the front passenger side of my engine (as seen in picture).

Yes your issues are very different from mine and the variance does seem like an electrical problem...

So I guess my next question is what is the condition of your alternator and the rest of the charging system? When this problem started was there any work/changes done to the truck right before? No visible problems and no work done. My car has been pretty reliable except for this problem.

If you have a voltmeter i would check the output of the alternator to the battery and make sure the battery is not down on fluid, the connections are corrosion-free, and the wiring is sound throughout the truck...
The battery reading is about 12.85volts

Any blown fuses or motors/circuits/lights that don't work out of the blue?
Nope.

This is starting to sound like a possible PCM issue...Especially after 4 pumps have been changed.. I really hope it is not...

 

[ErnieX]

That is the OHV engine. That is not a fuel pressure regulator.

EE

 

[Diff Whack Daddy]

Agreed, that is the OHV motor. Weather it is a fuel pressure regulator or damper, have you replaced it? Whatever the case is, that device is responsible for controlling, or regulating the pressure on the fuel rail. My Chilton's manula calls it a regulator, but let's not get into the tomato potato war.

The fuel pump just spins, creating about 65 to 95 psi. That device controlls the pressure by limiting the amount of fuel being sent back to the tank. If it's stcking, either open or closed, that will cause dramatic spikes, high and low, in fuel pressure. This could have been your problem the whole time.

If you still have the fuel pumps that you removed. Hook them up to a battery and see if they spin.

 

[rickpotz]

ErnieX and Diff Whack Daddy,
Thanks for your info.

Is there a way to test this part that regulates fuel pressure?
I haven't replaced it but believe it is almost as expensive as the fuel pump.
The dealer claims that these rarely go bad.

Thanks again.

 

[Diff Whack Daddy]

That doesn't make any sense. rockauto.com lists the fuel pump for $88 and the fuel pressure diaphram for $56.

The dealer said they rarely fail, but he didn't say never. After the second fuel pump replacement, it's time to start looking at other things, and since that's the last mechanical element, and that is what controls your fuel pressure at the rail, and you have already stated that you are getting spikes between 10 and 60 psi, the fuel pressure diaphram would be the most logical next step.

 

[n0xdw]

That is a damper not a regulator and if it goes bad it will leak fuel out the vacuum line into the intake flooding the engine and making hard to restart hot. Probably not your problem. Ck your lines for any kinks etc. And yes the engine is the OHV or push rod engine.

 

[Diff Whack Daddy]

Two questions.

First. Will it leak fuel into the vacuum in every possible scenario of going bad?

I find it hard to believe, that in every single case, that it will leak fuel into the vacuum line. I have seen many cases of diaphram based pressure regulator valves failing and not leaking anything, as well as the complete opposite of a 150 psi pinhole stream of water that draws blood. Yes, personal experience. The fact is, the diaphram loses it's abilty to regulate the output, or the input pressure to it.

Second. What else is there in the fuel system that controls the pressure at the fuel rail?

I don't care if you want to call it a diaphram, regulator, or a damper. According to autozone, it's a damper, Schucks calls it a regulator, but neither sell a direct OEM replacement. My Chilton's manual uses the generic term regulator as well. rockauto.com calls it damper. Here is a picture of the item that is sold by rockauto.com for $56 which is exactly what rickpotz is taking a picture of.
Fuel damper sold at rockauto.com

I just got done swaping the entire fuel system from one vehicle to the other and there is nothing but a pump, fuel pressure (insert word of choice here) and a filter. This fuel system has been used on OHV from 1991 to 2000 and on the 89-90 broncoII's and rangers prior to that and has not changed.

Just to eleviate control questions, the PCM, or ECU if you prefer, sends an on off signal to the fuel pump relay where 12VDC (or 13.5 to 14.4VDC with the engine running) to the fuel pump. There is no varied voltage to the fuel pump. I do recommend checking you voltage off idle (about 1500 rpm) to ensure that the alternator is putting out a steady voltage of no more than 14.5VDC. Fluxuating voltage can indicate a bad voltage regulator or alternator which can be harmful to some un protected circuits, the fuel pump being one of them. Most of the electronics in cars have inductors and capacitors to protect from voltages surges and drops where the fuel pump is a direct connect. These power fluctuations may also be noticed in the brightness of the dome and headlights.

 

[rickpotz]

That doesn't make any sense. rockauto.com lists the fuel pump for $88 and the fuel pressure diaphram for $56.

The dealer said they rarely fail, but he didn't say never. After the second fuel pump replacement, it's time to start looking at other things, and since that's the last mechanical element, and that is what controls your fuel pressure at the rail, and you have already stated that you are getting spikes between 10 and 60 psi, the fuel pressure diaphram would be the most logical next step.

I checked the part at the front. They call it a pressure damper. According to what I found it wouldn't create this problem. I did take it off. Inspected it and tested the diaphram side. The diaphram is good and according to some other articles I read, they claim if the diaphram is good the unit is good so I went with that. I cleaned and put it back on the car.

The expensive part I was speaking of was a geniune ford part price.

Thanks for the feedback.

I'm talking with a ford guy now. You know one of those online guys that you pay a little money for. He claims that if the voltage remains good at the pump when the pressure goes down then the pump is bad.

If the voltage drops, then I have to trace the problem.

At this point, I tested the voltage at the inertia switch and it seems to stay steady at when the pressure drops. I'm assuming that it will do the same at the pump. But you never know until you try!

I have removed the pump and attached it to the battery. I've pumped about
25 or 30 gallons of fuel through it. One bucket to another. No problem butttttttt the ford guy still says that if the voltage at the pump remains steady when the pressure drops it is the pump. We'll see.

 

[rickpotz]

That is a damper not a regulator and if it goes bad it will leak fuel out the vacuum line into the intake flooding the engine and making hard to restart hot. Probably not your problem. Ck your lines for any kinks etc. And yes the engine is the OHV or push rod engine.

I'm assuming that it works similar to an old style transmission diaphram or modulator? If the diaphram goes bad the unit stops functioning.
Which leads me to believe you're right about the gas leak.
Most faulty modulators leak when the diaphram goes.
I used to be an tranmission rebuilder.
I've sucked on many diaphrams! ha ha

Just wanted to say thanks for your feedback also.

 

[ranger7ltr]

Two questions.

First. Will it leak fuel into the vacuum in every possible scenario of going bad?

I find it hard to believe, that in every single case, that it will leak fuel into the vacuum line. I have seen many cases of diaphram based pressure regulator valves failing and not leaking anything, as well as the complete opposite of a 150 psi pinhole stream of water that draws blood. Yes, personal experience. The fact is, the diaphram loses it's abilty to regulate the output, or the input pressure to it.

Second. What else is there in the fuel system that controls the pressure at the fuel rail?

I don't care if you want to call it a diaphram, regulator, or a damper. According to autozone, it's a damper, Schucks calls it a regulator, but neither sell a direct OEM replacement. My Chilton's manual uses the generic term regulator as well. rockauto.com calls it damper. Here is a picture of the item that is sold by rockauto.com for $56 which is exactly what rickpotz is taking a picture of.
Fuel damper sold at rockauto.com

I just got done swaping the entire fuel system from one vehicle to the other and there is nothing but a pump, fuel pressure (insert word of choice here) and a filter. This fuel system has been used on OHV from 1991 to 2000 and on the 89-90 broncoII's and rangers prior to that and has not changed.

Ford changed the fuel system from the standard return line to returnless fuel system in 99...That was on the Explorer and the Ranger as well...

And I question whether the extra line to the tank is a return line or a vapor line..I have an extra tank in my garage and the only lines to/from it are the pressure line from the pump/sender and the vapor line in the tank itself...

The part at the pass front end of the fuel rail is called a pressure damper by Ford... There is no return line to the tank and the regulator is mounted in the tak on the sender unit...