99 explorer fuel pump

[Jered1011]

Hi guys this is my first post here. My 99 explorer wont start, I used to hear the fuel pump prime but now I dont. Checked relays, fuses, inertia switch, all good. Checked the fuel pressure and it was 0. Replaced the filter and still 0 pressure and no fuel pump priming. From what Ive read here it sounds like a dead fuel pump. I just wanted to run this by you all and see if there is anything I might have missed before I replace the pump. Thank you

 

[Turdle]

Does the check engine light turn on with the key turned on? if it does then you are on the right track.

If it does not, Check the PCM relay.

 

[410Fortune]

There is only one more thing to do before you drop the tank, well 1 thing but two steps

This has saved me from dropping many fuel tanks on Explorers:

What I do is unplug the fuel tank wiring connector.
It is mounted on the frame rail just above the drivers rear tire.
This is a black or grey 8 wire round plug.
One side goes to the tank, the other side comes from the truck

First I put power to the fuel pump using a jumper box or car battery. The fuel pump power is the two largest wires, pink/black is + and black/white is -
Does the pump power on and push fuel? If no then the pump is bad or wiring inside the tank

Second thing I do is test the truck side with a test light or multi meter and see if the fuel pump wires get power from the truck when the key is turned to ON
You should see battery power for a second or two when you turn the key
This verifies the EEC and fuel pump Relays and fuses are in good working condition

If the pump runs AND you have power on the truck side then the issue is with the connector in your hands.

After running these tests you can feel confident about dropping the tank and replace the pump. This is not a terrible job on your truck, but not the most fun thing in the world either.
You will need some fuel line disconnect tools, I like to spray the inside of the fuel line connectors with PB blaster before I start to work them loose

Use a factory quality pump and strainer, I use Bosch or Motocraft most times, Carter or Walbro are also good

The search button can lead to threads on how to drop the tank and go about replacing the fuel pump.
I always plan on a fight with the fuel lines on about 5 out of 10 tanks......I have a myriad of fuel line disconnect tools in my collection, there are 3 types that work best on these lines
Try a search and let us know what you find out!

 

[lobo411]

There's one fast thing you can try: pound on the gas tank using a rubber mallet and then try to start the car. If it starts, then you know the fuel pump is bad.

 

[koda2000]

Fuel pump. I've replaced a 1/2 dozen of them. All mine gave up the ghost between 175K-200K. I recommend the Bosch 69128 fuel pump kit off eBay, usually around $50 w/free shipping. I've installed 6 of them with zero problems.

 

[imp]

There's one fast thing you can try: pound on the gas tank using a rubber mallet and then try to start the car.
If it starts, then you know the fuel pump is bad.

@lobo411

Or, that a bad connection existed in the connector, and the shaking re-made the connection. Which means, the trouble will likely come back. IMO, wigging the connector first, then if no pump, pound on the tank......imp

 

[koda2000]

@lobo411

Or, that a bad connection existed in the connector, and the shaking re-made the connection. Which means, the trouble will likely come back. IMO, wigging the connector first, then if no pump, pound on the tank......imp

IMO the weather tight connectors used on modern vehicles typically don't cause problems. When electric motors fail it's usually because the brushes are worn and don't provide adequate pressure on the commutator to energize the motor. This usually shows up when the weather turns cold and contracts the springs behind the brushes, which reduces the brush pressure further. Banging on the bottom of the tank may allow the brushes to make a better contact (it's never worked for me) but if your pump is anywhere around 200K it's due to be changed.

 

[imp]

IMO the weather tight connectors used on modern vehicles typically don't cause problems. When electric motors fail it's usually because the brushes are worn and don't provide adequate pressure on the commutator to energize the motor. This usually shows up when the weather turns cold and contracts the springs behind the brushes, which reduces the brush pressure further. Banging on the bottom of the tank may allow the brushes to make a better contact (it's never worked for me) but if your pump is anywhere around 200K it's due to be changed.

@koda2000
Brushless pump motors are gaining ground. Added problems for submerged pumps are encountered with diesel fuel: brushes are adversely affected.

"Submersion capability also allows for liquid cooling of the motor – which is especially beneficial for a small, high energy motor that can generate much heat.

For gasoline applications a benefit of submergibility is that the gasoline helps keep internal components from corroding. In a brushed system the non-submerged motor could be exposed to water and such – causing corrosion.

Conclusion

FUELAB decided to use Brushless DC Motors in our fuel pumps as the overall efficiency, long-life and reliability the technology offers is superior to that of brushless motors. Further, since more power can be obtained from a lighter motor, our fuel pumps are lighter, and they can provide more flow than a similarly sized fuel pump with a brushed motor."

See: Fuel Pump Motor Technology – Brushed DC Motors vs. Brushless DC Motors | Fuelab

 

[koda2000]

@imp - That may all be true, but to my knowledge the '95-'01 Explorer does not use a brush-less fuel pump motor.

 

[imp]

@imp - That may all be true, but to my knowledge the '95-'01 Explorer does not use a brush-less fuel pump motor.

@koda2000
Spoilt my daydreaming! imp

 

[Runnin'OnEmpty]

I cut apart my 04 Ranger fuel pump after replacement, and found that the brushes had worn into the commutator giving a poor connection. These pumps do wear out after a period of time.

One other thing to try is check the pump shut-off switch located at the firewall near the center, just above and to the left of the passenger footwell.These have a reset button on the top.

 

[imp]

I cut apart my 04 Ranger fuel pump after replacement, and found that the brushes had worn into the commutator giving a poor connection. These pumps do wear out after a period of time.

One other thing to try is check the pump shut-off switch located at the firewall near the center, just above and to the left of the passenger footwell.These have a reset button on the top.

@Runnin'OnEmpty
I am most impressed by your post. Few would have cut apart a fuel pump, much less understood what they saw therein. I peeked at your Profile and saw you have a technical background. That may explain it. Now, I pose this question to you; do you see any added danger in running an electric fuel pump OUTSIDE of the tank? Some do. Purely heresay, though. I used the so called "Low Pressure" pump Ford called out for frame-mounting on F-Series pickups, late '80s, early '90s, maybe, to provide ALL the fuel for conversions I did back in the '90s where older, carburetted vehicles were converted to EFI. They ran like a charm, only thing added to the fuel tank was a return line. Those Ford designated "Low Pressure" pumps actually worked in series with the in-tank pumps. Why they were even employed, I dunno. imp

 

[Jered1011]

I will give it a shot. Thanks guys

 

[Jered1011]

It was the fuel pump. Thanks for all the help everybody

 

[koda2000]

@koda2000
Spoilt my daydreaming! imp

Well whatever the technology of the Gen II fuel pumps, they wear out at around 200,000 miles. If I were to purchase another Gen II (which is unlikely at this point in time) and it had over 100K + on it I would replace the fuel pump as one of my first PM items before putting it on the road. Our only fuel pump that made it past 200K was the one in out '97 Sport. Makes me wonder if the return style of fuel system is easier on pumps than the return-less style fuel system. It's possible I guess as the fuel pressure on the return style system is approx 1/2 that of the return-less style system. Our '97 Sport had around 240K on it's original, dated OE fuel pump and it was still working perfectly, I just decided to replace it as a PM item.

 

[Runnin'OnEmpty]

@Runnin'OnEmpty
I am most impressed by your post. Few would have cut apart a fuel pump, much less understood what they saw therein. I peeked at your Profile and saw you have a technical background. That may explain it. Now, I pose this question to you; do you see any added danger in running an electric fuel pump OUTSIDE of the tank? Some do. Purely heresay, though. I used the so called "Low Pressure" pump Ford called out for frame-mounting on F-Series pickups, late '80s, early '90s, maybe, to provide ALL the fuel for conversions I did back in the '90s where older, carburetted vehicles were converted to EFI. They ran like a charm, only thing added to the fuel tank was a return line. Those Ford designated "Low Pressure" pumps actually worked in series with the in-tank pumps. Why they were even employed, I dunno. imp

Imp, thanks for the kind words. You're more familiar with external pumps than I am, since you've installed them. As you said, the biggest drawback is the heat that is generated, and being submerged helps the pump run cooler. As far as running an external pump goes, if the proper rated hose and clamps are used, and the pump is protected from road hazards, I see no particular danger. Cooling the pumps is the reason auto mfgs mounted them in the tank.

The Ranger pump failed at about 60K miles, which was way too soon and that's why I cut it apart. They are very simple inside with just a motor and vane to move the fuel. I suspect Ford had some faulty pumps around that time, with brushes that were too hard and wore into the commutators. I've seen many posts of premature failures on 04s particularly.

Jered, glad you got it fixed!

 

[imp]

Imp, thanks for the kind words. You're more familiar with external pumps than I am, since you've installed them. As you said, the biggest drawback is the heat that is generated, and being submerged helps the pump run cooler. As far as running an external pump goes, if the proper rated hose and clamps are used, and the pump is protected from road hazards, I see no particular danger. Cooling the pumps is the reason auto mfgs mounted them in the tank.

The Ranger pump failed at about 60K miles, which was way too soon and that's why I cut it apart. They are very simple inside with just a motor and vane to move the fuel. I suspect Ford had some faulty pumps around that time, with brushes that were too hard and wore into the commutators. I've seen many posts of premature failures on 04s particularly.

Jered, glad you got it fixed!

@Runnin'OnEmpty
Please be aware that the '04s do not run at constant speed. They are speed-controlled based on the pressure at the fuel rail. Pressure drops, more demand for fuel, PCM speeds up the pump. Actually, that is going on constantly, pump speed varying all the time to provide constant
pressure at the rail. Called "returnless system", only one fuel line to the rail. This results in much-increased pump life......supposedly. When I learned of this, I thought, these designers are nuts. But, I have an '04 with 165k, original pump, quiet as a mouse still, so, I dunno!

One added requirement of returnless was to monitor electronically the rail pressure (rather than mechanically via vacuum before) and fuel temp. Ford introduced a "Fuel Pressure and Temperature Sensor" mounted on the rail. That sensor tells PCM how fast to run the pump, varying speed constantly. WHAT IF the sensor fails? Stranded along the road? I wondered. No, they covered that possibility. Smart. FPTS fails, PCM defaults pump speed to MAXIMUM, throws CEL, pump output is max., runs eng. at higher than design pressure, pollutes (so what), dumps the extra fuel pumped back into the tank right at the pump! At about 100psi. So no dead vehicle by the roadside. It happened to me......otherwise I wouldn't know this ****, it ain't called out in Ford troubleshooting.

 

[410Fortune]

"They are speed-controlled based on the pressure at the fuel rail. Pressure drops, more demand for fuel, PCM speeds up the pump. Actually, that is going on constantly, pump speed varying all the time to provide constant
pressure at the rail."

Interesting information here I was not aware of. How exactly does the PCM speed up and slow down the pump? I would assume by varying voltage? We had return less fuel rails in 1998-2003 also, I do not think the PCM slows or speeds up these pumps? as the power to the pump comes from a relay?
First I have heard of the 04+ style return less fuel doing this

 

[imp]

"They are speed-controlled based on the pressure at the fuel rail. Pressure drops, more demand for fuel, PCM speeds up the pump. Actually, that is going on constantly, pump speed varying all the time to provide constant
pressure at the rail."

Interesting information here I was not aware of. How exactly does the PCM speed up and slow down the pump? I would assume by varying voltage? We had return less fuel rails in 1998-2003 also, I do not think the PCM slows or speeds up these pumps? as the power to the pump comes from a relay?
First I have heard of the 04+ style return less fuel doing this

@410Fortune
Good points! First one must understand that pumps are "constant volume" devices. That means each pump revolution moves "X"-amount of liquid, no matter what, since liquids are incompressible. In hydraulic systems, it's customary to size the pump volume slightly larger than the greatest anticipated need: therefore, there is always "excess" fluid being moved, part goes to do desired work, the remainder is "dumped" back to the tank by a relief valve. Moving that extra fluid uses energy and creates heat, but is necessary by usual design methods.

Since D.C. motors are easily speed-controlled, today's returnless fuel systems have a specialized sensor mounted on the fuel rail called the "Fuel Pressure and Temperature Sensor." It constantly feeds a signal to the PCM, which detects changes in pressure: the fuel pump's speed is being constantly controlled to maintain a narrow band of fuel pressure, regardless of engine demand. Sudden open throttle instantly bumps up pump speed to keep pressure constant, and vice-versa, so no effort is wasted pumping fuel back to the tank. All fuel delivered by the pump gets burned in the engine, IOW.

Ford Engineers think of a lot of scenerios. What if the FPTS fails? Pump stops, vehicle stalls. They foresaw the possibility, and programmed-in a default which makes fuel pump run at maximum speed, lots of lights and whistles warn the driver, vehicle operates very inefficiently, even making some black smoke, but doesn't quit running. The pump has a built-in relief valve which I have heard dumps excess fuel right back into tank at about 100 psi. Under normal conditions, that relief is always closed.

'98 to '03 system you mention I have only fuzzy knowledge of. I believe they had a Fuel Pump Control Module which was eliminated in 2004, that actually did vary the pump speed, but not as accurately as desired, until the FPTS was added. Many threads exists about corroded FPCMs, leading me to believe they were electromechanical devices, rather than electronic alone. Quick search was fruitless. Several years ago I got the code for Fuel Rail Pressure & Temperature Sensor, knew only that it was used to run the pump, imagined crapping-out along the road. Bought and installed a new sensor, never had any running symptoms with the bad one......Learned later of the fail-safe pump set-up. I'll try to find more on '98-'03 returnless.
(whew!). imp