Looking for Help: Fuel Pump Dead

[95beater]

My 95 Explorer (4.0) died suddenly Sunday night (very cold Chicagoland wait for tow truck) and would not restart. It appears that the fuel pump is dead. When I've had fuel pumps go dead in other cars, I usually get a whine or a poor running car prior to death. There was no warning, just 5 seconds of sputtering and a rolling stop. Strange.

I tested the ECM with the key in the ON position and got nothing. After cranking it a few times, I got these codes: 116, 636, 114, 633, (different sensors out of temp range) and 542 (fuel pump).

Hoping for an "easy" answer, I replaced both the fuel pump relay and ECM relay, and looked for a "popped" inertia switch. No luck

Then I followed the directions in my Haynes manual to test for fuel pump problems. Following their advice, I used a test light and looked for a "hot" wire in the relay plug harness (with the ignition off). Found it. Then I looked for an second "hot" wire with the ignition in the on position. According to Haynes, this wire is supposed to stay "hot" for "three seconds" once the key is put into the ON position. I found the second hot wire in the harness, but it does NOT turn off, it stayed hot the whole time. Is this a typo in the Haynes manual or is there something wrong with the signal coming from the ECM?

Something else to consider. The driver's side windshield washer cowl nozzle froze, cracked, and broke about one hour before this happened (fluid good to -32F, whatever) . I'm sure that the firewall got soaked along with the back of the engine. I was sitting still, so I don't think fluid got blown all over the place. But, just something to think about.

Any help would be greatly appreciated.

 

[dogfriend]

There is a diagnostic chart on the Autozone web site, check here:

http://www1.autozone.com/servlet/Ui..._us/0900823d/80/0b/99/39/0900823d800b9939.jsp

The charts are near the bottom of the page, after the removal instructions. I didn't see any mention of a 3 sec test. There are a couple of tests that say the system is supposed to maintain pressure for at least 3 min after power is removed (Check Valve Test).

 

[95beater]

Autozone, Who Knew?

I've dropped hundreds in that store, I had no idea that they had diagnostic stuff on their website!

I'll give it a shot and let you (and everyone else) when I get it figured out.

Thanks!

 

[dogfriend]

Its actually a copy of the Chilton's Ford Explorer Manual, but its free, which is a really good price.

 

[BrooklynBay]

If you know the color code of the wiring going to the fuel pump, and the inertial switch is OK (checked with a continuity tester), then I would say to actually "jump" the connection to the fuel pump just to rule out any possibility of a bad fuel pump. If you don't have any relays, ECM, or inertia switch wiring in the way to make it harder to diagnose, then this would be either a go/no go test. Just make sure that there isn't any other wiring in that series circuit besides your fuel pump, and keep the polarity the same.

 

[95beater]

With almost 160k on what appears to be the orginal pump (I got a pile of service records when I bought this truck used) I'm going to replace the pump. Even if the pump wiring is culprit, I'm sure that I'll have to drop the fuel tank anyway. With it out, it only makes sense to change it.

Thanks for the responses.

 

[BrooklynBay]

When you drop the fuel tank to replace the pump, disconnect the wiring harness at the tank, and hook up a test light on the pump wires. When you turn on the electrical system, it should light up for a few seconds, then go out. If you crank the engine, it should light up again. If this doesn't happen, then it's in the wiring. At this point, you could also check the pump without removing it by either putting some electricity on it, or by using a continuity tester.

 

[jfh123]

Hey, I'm in the northwest burbs too. Vernon Hills.
I'm having a problem related to the fuel pump as well.
Mine is a 99 with only 36,000 miles.
I'm not sure if mine is the pump or some control circuit for the pump.
It does not want to start about 1/3 of the time I try it.
Usually when I turn the key to the on (not start) position I hear the pump for about 3 seconds, other times I dont hear it.
I have swapped the relay and it did not help.
I did a test where I just removed the fuel pump relay and shorted the contacts in the power distribution box to simulate a 'energized relay' providing power to the pump and I hear the pump run almost every time.
Almost, but not every time, so I'm not sure if it is the pump or whatever is driving the relay to power the pump.
Are you replacing the pump yourself? I am thinking about it but dropping the tank sounds like a real pain. Plus I'm not sure if jack stands alone will give me enough room to work under there.

 

[Glacier991]

Relays are a common culprit. Before you drop the tank... a very unfun job.... heed the good advice from Brooklyn Bay.... I have replaced a pump only to find out it was some exotic electronic relay system glitch (this was in a mid 90's FORD sedan). Now I look at the simple things (like relays) first. I'd be curious to hear, but I doubt anyone has had a bad inertial switch... just seems so improbabable.

Think about what the computer does. You turn the switch to on. Because your fuel pressure probably has bled to zilch, the computer actuates the relay to fire up the fuel pump... but only for a few seconds to pressurize the system for a start. Once the engine starts the fuel pump runs continuously, with unneeded fuel fed back to the tank. If the relay was bad, you would never have the pump running, which could easily be thought of as a bad pump.

Fuel pumps can be "luck of the draw" in terms of service life but as a rule are long lived these days.

 

[95beater]

Fuel Pump Update

I just replaced the fuel pump, and it worked. I’m a one man band, so it went pretty slow, about 5.5 hours (included trip to Autozone and Pepboys) and I got really dirty. The whole job can be done with a standard tools, a metric socket kit (a long extension is helpful for the strap bolt), and a fuel-line disconnect tool.

Here are the highlights:

Note: My fuel lines were already depressurized (the fuel pump died, and the engine ran out of gas). If your fuel line has pressure in it still, you’ll need to depressurize the system. Search other links on how to do that.

· I used a standard floor jack boosted with a 4”x4” piece of wood to get the truck high enough to clear some mid-sized jack-stands. Place the stands on the frame.
· I took off the left-rear tire.
· I siphoned out the old gas. I used about 12’ of tubing from ACE and a hand automotive vacuum pump to start the flow. 12’ was enough tubing to get the line OUT of my garage and into gas cans in the driveway, but I sure wish I had more. It took about 45 min to drain a full gas tank. I ran out of gas cans so I started dumping gas into my wife’s van. I added drygas to the van (and eventually to the Explorer). I suspect that water in the tank could have something to do with the pump failure.
· The skid plate came off easily, but had enough mud caked in it to choke a horse.
· I loosened the front bolts to near the last threads, put the jack under the tank, and then removed the rear strap.
· The filler and vent hose were attached to the tank with large quick connects, and I didn’t have a “special tool” big enough. Instead, I unbolted the filler neck and allowed the filler and vent hoses to slide through the frame/body down with the tank. It appeared that Ford actually put bends in the hoses for this purpose.
· I took off the front tank bolts and dropped the tank with the jack.
· The feeder and return lines came off easily with a cheapie disconnect tool from Autozone. The tank vent was a different issue, the plastic “quick connect” broke off. I replaced it with fuel regular high pressure fuel line from Autozone and some hose clamps. I used zip ties to secure the new line to keep it from moving/abrading.
· I removed the pump unit from the tank (mine was held on with bolts, I hear some newer models are held on with a ring). I replaced the pump with a Carter Brand (lifetime warrantee, Pep Boys) for about $140. The instructions that came with the pump were pretty straightforward, a couple of screws and some wire crimps and I was on my way. Be careful, the old pump has a lot of gasoline in it that will spill when you take it out.
· Reverse order to put everything back together.

I also changed the fuel filter, which took about 30 minutes due to the pounds of dirt that were caked on it. It used the same fuel disconnects

Some things to think about: If you are going to “do it your self” in your home garage, I strongly recommend doing this job during the day, with the rear of the Explorer facing near the garage door. For the most part, I had enough natural light to do the work. A drop light and spilled gas could be a disaster. Also, those with their hot water heaters in the garage should also be careful (turn off the pilot light). Remember that gas vapors are heavier than air and will stay on the floor of your work area.

As far as the question from JFH123, I’m not sure how to field that one.

Good Luck to those changing their pumps, and thanks to all that helped!