94 Explorer won't start

[whowouldfigga]

Well it was bound to happen. After fourteen years of use and over 250,000 miles my 94 expl. left me stranded. Out of nowhere with no warning I couldn't get her to start after work. Things I have checked before it got dark.

• There is fuel in the tank
• Engine turns over but it won't fire.
• Swaped Fuel Pump relays but wouldn't start.
• No check engine light.
• Checked for spark and yes I have spark.

I wanted to check for fuel or fuel pressure but I don't have a guage. Read the sticky. Can I just press the shrader valve in front of the coil pack on the fuel rail to check for pressure? I tried to listen for the fuel pump when you turn the key on but the road where the suv is located is very loud.

Any step by step checks would be greatly appreciated. Thanks in advance.

 

[fixxxer]

When you turn the truck on, before the starter engages, do you hear the fuel pump run? You should be able to hear it run for between 1 and 3 seconds when you turn the key to the "run" position.

 

[MrShorty]

No check engine light.

Do you mean the CEL doesn't come on KOEO (key on engine off)? If that is what you mean, that could indicate a problem with the PCM power supply.

Can I just press the shrader valve in front of the coil pack on the fuel rail to check for pressure?

You can, but that only answers the question, "Is there pressure or not?" It is possible for the system to have pressure, but not enough. In that case, you would need a gauge to determine if there's enough pressure.

 

[whowouldfigga]

When you turn the truck on, before the starter engages, do you hear the fuel pump run? You should be able to hear it run for between 1 and 3 seconds when you turn the key to the "run" position.

The road noise is so loud I couldn't hear a thing. When I get back to the car I will try and listen to it again.

Do you mean the CEL doesn't come on KOEO (key on engine off)? If that is what you mean, that could indicate a problem with the PCM power supply.



You can, but that only answers the question, "Is there pressure or not?" It is possible for the system to have pressure, but not enough. In that case, you would need a gauge to determine if there's enough pressure.

I will check to see if the check engine light (CEL) comes on with the key on engine off (KOEO) Thanks for the definitions as I am new to the abbreviations.



I will check for the pump run noise and will check for any pressure at all. If I have no pressure than bingo. If I have some pressure than I will have to get a gauge.

Thanks guys and gals.

 

[ld50]

You checked the emergency fuel pump shut-off didn't ya?
Plastic housing under the passenger side carpeting under dash with a reset button on it?
long shot, but a friend of mine shut mine down with well placed kick once.

 

[whowouldfigga]

You checked the emergency fuel pump shut-off didn't ya?
Plastic housing under the passenger side carpeting under dash with a reset button on it?
long shot, but a friend of mine shut mine down with well placed kick once.

I will be checking it today. I couldn't find it in the car and I knew it had one. The sticker under the hood told me so. No passengers in the car though. What are the chances of the emergency switch going bad.? Thanks for the location hint.

 

[DeRocha]

The switch rarely goes bad.. Often it is the fuel pump, or it's relay, or computer that go.. Check the fuel pump fuse (located under the hood near the battery). It could be blown indicated an old/worn fuel pump..

The fuel pump inertia switch is located under the glove box behind the carpet as pictured below When you turn the key from off to run the fuel pump will energize for a few secs to pressurize the fuel system. Normally if your quiet you can near this. If you can't hear the pump you'll need to but a meter on the inertia switch and test for 12v as you turn the key to run.. (note 12v will only show up for 2 secs so you'll need to read it quick)

Click on pic for full size

 

[whowouldfigga]

Ok I got the car towed home tonight. I checked the emergency cutoff switch and it was not deployed. I pushed just in case. I would like to test it. Can I unplug it and use a ohm meter and check for continuity?

I do not hear the pump wind up when I turn the key to on.

The check engine light does flash when I turn the key.

I put a new relay in the fuel pump slot and still no start.

I used a meter on the fuel pump relay socket and found the following.
Slot 30 is always hot.
87 has no volts
85 is grnd
86 is hot with the key on.
I figure 86 is the switch and with the key ON 30 and 87 connect and complete the circuit. Regardless I can feel the relay switch when I turn the key on.

I checked all the fuses by the battery under the hood with a ohm meter and they are all good. I can't find my owners manual.

I pushed on the schrader valve in front of the coil pack on the fuel inj. rail. A drop of gas came out. I then turned the ignition to ON, pushed on the schrader valve and nothing. Not even a drop.

It got dark so I was not able to crawl underneath the car and check the power to the fuel pump. At this point I am assuming my original Ford fuel pump with over 250,000 miles is dead. When I get a chance I will verify power to the fuel pump. I will search for the fuel pump location and replacement on the forum. Any shortcuts or links to a post would be appreciated. My Explorer is a 1st gen. 1994. If I've missed something let me know please. Thanks again!

 

[choodeee]

THAT HAPPENED TO MINE THE OTHER DAY!!!!!!!

my dad is a retired cop and knows a tiny bit about cars
but what he did was turned the key then threw it in drive and took it to the shop down the road and just kept the rpms up (other wise it stalls)

but there at the shop they said it had something to do with the trans arm ??
or some arm i think the guy said, well they cleaned it off and then i guess it ran fine

he did also say that the fuel pressure needs to be tight like making sure your fuel cap is on all the way and that at least my explorer ('00) has a them chips in them and if that is like dirty at all it wont start up.

i dont really have a clue what the hell i am talking about to be a hundred percent honest cause i dont like engines but thats all i heard soo i hope i could help out a little bit.

 

[whowouldfigga]

I got underneath the car this morning and found a plug above the passenger rear axle. I am guessing this is the fuel pump connector. I took a reading at the pins and one pin had 8.5 volts and the other had 7.5 volts. My diehard battery is low down to 11.0v. Why am I not getting at least 11.0 volts?

 

[DeRocha]

To confirm the pump is no longer getting power check the fuel pump inertial switch located below the glove box. Pull back the carpet behind the glove box and find the fuel pump inertia switch (pictured below). Use a meter (or test light if thats all you have) and connect either wire of the switch to HOT, and then ground the meter to a suitable ground. The meter should read 12v when the fuel pump is running and ~7v when its not.

As you may already know the fuel pump will only run when given 12v... When you turn the key from run to start the inertia switch (pictured below) will see 12v for only 2 secs or while the tac registers > 0 RPM. After 2 secs of zero RPM the computer will shut off the fuel pump relay and you'll only see ~7v at the inertia switch and fuel pump. Seeing 7v is weird but that is what you'll get if you check the wiring.

 

[whowouldfigga]

To confirm the pump is no longer getting power check the fuel pump inertial switch located below the glove box. Pull back the carpet behind the glove box and find the fuel pump inertia switch (pictured below). Use a meter (or test light if thats all you have) and connect either wire of the switch to HOT, and then ground the meter to a suitable ground. The meter should read 12v when the fuel pump is running and ~7v when its not.

If I test both sides this will also confirm that my switch is good. I could also use the ohm meter across the switch if I disconnect it.

As you may already know the fuel pump will only run when given 12v... When you turn the key from run to start the inertia switch (pictured below) will see 12v for only 2 secs or while the tac registers > 0 RPM. After 2 secs of zero RPM the computer will shut off the fuel pump relay and you'll only see ~7v at the inertia switch and fuel pump. Seeing 7v is weird but that is what you'll get if you check the wiring.

I was not aware that after 2 seconds of > 0 rpm the volts drop down to ~7v. I also was not aware that I had to test the wiring for 12 volts when the key switch goes from run to start. I took a reading at the fuel harness under the car with the key set to run only.

In summary I will check for 12 volts (2 seconds) at both sides of the inertia switch when I turn the key from run to start. I can also check the voltage at the pump harness for 12 volts (2 seconds) when someone turns the key from run to start.
As a last test can I also give the fuel pump a external source of 12 volts from a spare battery and see if it runs?

Please correct me if I am wrong. Thanks.

 

[DeRocha]

...As a last test can I also give the fuel pump a external source of 12 volts from a spare battery and see if it runs?

Please correct me if I am wrong. Thanks.

Yes... you can run a test wire with a 20A fuse from the battery (or suitable power source) to either the inertia switch or fuel pump. Other members have done this to get past broken fuel pump relays or EEC issues.

 

[CmdrPopNFresh]

this thread has a pretty quick way to change the fuel pump....and it makes it easy for future pump replacement



http://www.explorerforum.com/forums/showthread.php?t=182160

 

[whowouldfigga]

Success!!!
I just wanted to send everyone a thank you for helping me diagnose the problem.
My last test at the inertia switch and at the fuel pump harness plug confirmed that the fuel pump was dead. Special thanks to DeRocha for clarifying the voltage issues when I was doing my testing.

The whole job took me about 2.5 hours and one neighbor to help replace the tank and skid plate. Luckily my explorer is a Florida vehicle and all the bolts came off with ease. One tip I would like to pass on would be to clean the top of your tank when you drop it while the old pump is still in. Sand and dirt have a way of gravitating towards the gaping huge hole left by the removal of the pump. I bought a fuel filter as well but I will replace it next week after I run a tank of gas through the vehicle. The car started up like a champ. In retrospect I was having a slightly delayed start recently and the fuel pump seems to have resolved the issue.

The local shop quoted me $200 for the pump and 3 hours of labor @ $80.00hr.
My cost?
Parts:
Motocraft pump. $165.00
Fuel line tool. $21.00
Motocraft fuel filter. 14.99
Dirty finger nails.
Couple of laughs with the neighbor. He about hit his head on the drive shaft when I told him to make sure and not scratch the paint on the skid plate up.

Priceless!!!

 

[sqhurt]

To confirm the pump is no longer getting power check the fuel pump inertial switch located below the glove box. Pull back the carpet behind the glove box and find the fuel pump inertia switch (pictured below). Use a meter (or test light if thats all you have) and connect either wire of the switch to HOT, and then ground the meter to a suitable ground. The meter should read 12v when the fuel pump is running and ~7v when its not.

As you may already know the fuel pump will only run when given 12v... When you turn the key from run to start the inertia switch (pictured below) will see 12v for only 2 secs or while the tac registers > 0 RPM. After 2 secs of zero RPM the computer will shut off the fuel pump relay and you'll only see ~7v at the inertia switch and fuel pump. Seeing 7v is weird but that is what you'll get if you check the wiring.

Don't mean to hijack the thread but was wondering if both wires at the shut off switch should have the 12 volts an both drop to 7 volts when the key is on engine off? Im only getting the 12 volts an drop to 7 on one wire

 

[whowouldfigga]

^^The inertia switch is wired in series. In other words the current flows in one leg and out the other. ( -----> Switch ----->). The answer is Yes you will only have voltage at one wire on the plug when the switch in unplugged. When the switch is plugged in you should get voltage at both wires if the switch is reset (button pushed in) and working properly.

 

[DeRocha]

Glad to hear you've solved the mystery and have gotten your X back on the road.. Dropping the tank can be a PITA especially if you've never dealt with finicky fuel line connections before... BTW I dropped my tank 3 weeks ago for the 4th time (Once for the fuel pump, twice for brake lines, and once when installing new body mounts)

 

[rhvell]

Won't Start Fix

I had replaced everything under the hood and ended up towing the car to a friend. He disconnected the dpfe sensor and the car would start. Disconnect the wiring going to the dpfe or goggle dpfe sensor and read focus hacks:. hope that helps.
Ronnie

 

[rhvell]

Won't Start Fix

I had replaced everything under the hood and ended up towing the car to a friend. He disconnected the dpfe sensor and the car would start. Disconnect the wiring going to the dpfe or goggle dpfe sensor and read focus hacks:. hope that helps.
Ronnie