99 ford explorer won't start

99 ford explorer with 4.0 vin E first number of vin 1 ok this truck all a sudden will not start. I hooked up a fuel pressure gauge and turn the key and get 10 psi max, do this a few times and it does go up to 56 but never off 1 prime.

What is the fuel pressure suppose to be and should this thing bring the fuel pressure up with 1 prime and not have to turn the key on and off a half dozen times?

This truck has 130,000 on the original pump.

Those symptoms sound pretty indicative of a failing fuel pump. You could try changing out the fuel filter in case it is just resisting flow, but with the age the pump's probably worn out.

I don't find the fuel pressure specification in the service manual, but suspect it's something like 35-60 psi for KOEO. Your reading of 10 psi definitely sounds low, and the pump should prime to the KOEO spec on the first attempt.

-Rod

That's what I thought, I just didn't know what the pressure is supposed to be on these as I don't work on many fords. I will be replacing the fuel pump tomorro and my friend insists on using the cheapest pump. I've warned him against airtex pumps but he needs his truck right away and our lps only carries airtex and being labor day..... I told him the second time isn't free...lol

Ok guys I put in the new fuel pump and it still doesn't start except this time you don't hear the 3 sec prime. I check the relay and there power going to both terminals, then went over to the cutoff switch and I only get low voltage on the pink wire. Tried resetting it and that didn't work. I do have 7 volt's to 1 wire on the pump harness EDIT NOW there is no voltage to this wire..... Could it be it needs a new cutoff switch?

The switch won't cause low voltage on only one terminal. If the supply terminal to the switch is low, that would indicated a poor connection elsewhere in the system. The supply current may be too low to give a meaningful voltage measurement at the output terminal, although that would seem somewhat odd. I would suggest unplugging the inertia switch and using a test light to check for voltage to the switch. The reason I suggest a test light rather than a multimeter is the input impedance of a multimeter is very high and won't load the circuit. The test light may not light if the connection is too poor to source more than a few milliamps of current. If the test light illuminates, then with the light still in the circuit, measure the voltage to the test light. If the voltage is near battery voltage, then you might have an issue between the switch and the fuel pump that is causing the problem, or the universal pump you installed may not have been wired up properly. Any chance you might have reversed the power and ground leads on the motor? What kind of warranty did you negotiate with your friend? ;)

-Rod

There is no voltage at the pump harness also nothing on the green with yello, Moved on to the reset switch, I get 9.97 on the gray with orange stripe and a 2 second flash with the pink &black stripe and nothing on the green with yellow stripe. No warranty with my friend lol I told him buying the cheapest part you always get what you pay for. I checked the harness plug and all the pins looked fine with no corrosion. Ok so this is what I no.
Installed new Airtex pump
No 3 sec prime
Has power at the relay on both terminals and the fuse is good and also I swapped the relay with another on the block with the same results. 2 terimals have 12.5 volts on fuse block where relay mounts.
At the inertia switch there is 9.7 volts on the gray with orange stripe, 2 second light on the pink with black stripe( When you turn the key onto the on position). And nothing coming out of the green with yellow stripe witch is the fuel pump wire.
won't light up a test light on any terminal on the pump harness.

How do I test the inertia switch being I can't get any juice to the green and yellow wire? Does this mean the inertia switch is bad?

Also the theft light is blinking is this normal?

The switch won't cause low voltage on only one terminal. If the supply terminal to the switch is low, that would indicated a poor connection elsewhere in the system. The supply current may be too low to give a meaningful voltage measurement at the output terminal, although that would seem somewhat odd. I would suggest unplugging the inertia switch and using a test light to check for voltage to the switch. The reason I suggest a test light rather than a multimeter is the input impedance of a multimeter is very high and won't load the circuit. The test light may not light if the connection is too poor to source more than a few milliamps of current. If the test light illuminates, then with the light still in the circuit, measure the voltage to the test light. If the voltage is near battery voltage, then you might have an issue between the switch and the fuel pump that is causing the problem, or the universal pump you installed may not have been wired up properly. Any chance you might have reversed the power and ground leads on the motor? What kind of warranty did you negotiate with your friend? ;)

-Rod

No no chance.

Fuse #9 (20-amp) in the Power Distribution Panel feeds the fuel pump relay. When the PCM closes the relay, the relay provides power to both the PCM and the fuel pump inertia switch on the Dark Green/Yellow wire. When the switch is reset, the power from the Dark Green/Yellow wire should flow through the switch to the Pink/Black wire which feeds the fuel pump. If the inertia switch is tripped (open) the light in the instrument cluster is grounded via the Gray/Orange wire through the fuel pump.

From your measurements, it sounds like the Gray/Orange wire is giving you 9.7 volts because of the current limiting provided by the bulb. If the inertia switch were shorting that line to ground through the fuel pump you would measure ground potential on that wire. Since you have battery voltage on the Pink/Black wire, you must also have battery voltage on the Dark Green/Yellow wire. I'm looking at the factory wiring diagram which indicates that the Dark Green/Yellow wire is the supply wire from the relay and the Pink/Black wire is the fuel pump supply line. You should be able to use the continuity setting of your meter to confirm which wire has continuity to terminal 5 (may also be terminal 87) of the fuel pump relay.
http://i538.photobucket.com/albums/ff342/raschmidt/Automotive/1998ExplorerFuelPump.jpg

-Rod

Thank You shorod for helping me get this sorted out. Now when I turn the key on, the theft light flashes really fast and continuous. Could this system shut down the fuel pump if somehow his key went bad. Could this be the problem? I'm learning more about fords everyday... lol

Also you say the green/yellow wire is the feed line from the relay, I do not have any power to this wire at the inertia switch location. I did swap the relays with another one on the fuse block and it didn't make a difference. Also when you turn the key on you can feel the relay clicking in.

Yes, the quickly flashing Theft light would indicate an issue with the PATS system, and that would prevent the vehicle from starting. The Factory Service Manual doesn't specify how the PATS system prevents the engine from starting, it just indicates that if the key is not recognized as a programmed key it will, via the PCM, prevent the engine from starting. The Fuel Pump Relay is controlled via the PCM so it's very likely that the PATS system could prevent the relay from closing. However, since you are getting a relay click when turning the key to Run/Start, the inertia switch should be getting power. Are you positive that it's the Fuel Pump Relay you are feeling click and not another relay located nearby? Did you disconnect the battery when you changed the fuel pump? The PATS system should retain the programmed keys even when the battery is disconnected, I'm just trying to draw a tie between work you did and the issues you're having now.

Since you are measuring voltage at the inertia switch, albeit on what the diagram would indicate is the wrong wire, I think I'd not focus on the PATS just yet and troubleshoot the area you worked on (fuel pump). By chance have you checked for fuel pressure at the fuel rail with the new pump? Pumps tend to get noisy as they get older, so just because you don't hear the pump now doesn't necessarily mean that it is not running....

As you can see from the wiring diagram above, the dark green/yellow (DG/Y) wire is what connects the fuel pump relay to the inertia switch. If you have battery voltage on the Pink/Black (PK/BK) wire, it has to be coming from the DG/Y wire. I will caveat that this diagram is from the 1998 service manual rather than the 1999, but I don't think they made a wiring harness change until 2002. Since you are measuring power though at the PK/BK wire, it might be interesting to temporarily jumper between the PK/BK wire and the DG/Y wire at the inertia switch connector just to verify if the pump runs.

I think you might want to make the continuity check from terminal 5 of the relay socket to the DG/Y wire. If you have continuity there, then you've confirmed the wiring diagram above matches your friend's Explorer. If you don't have continuity there, then check for continuity from the socket to the PK/BK wire. If you don't have continuity there either, then check for resistance from the PK/BK wire at the inertia switch connector to a good, clean ground. You'll probably see something less than 10 ohms but probably more than 3 ohms. If you measure an open circuit from PK/BK to ground, then I think you have an issue in the wiring from the inertia switch through the fuel pump to ground.

-Rod

Thks for the info rod, As for the work I've done so far all I did is drop the tank and put in a new fuel pump. I'm beginning to think the problem is with the pats system all along. Installing my fuel gauge gives the same results as with the old pump 10 psi and will rise when you cycle the key on and off. Will do more testing as you suggested.

Ok updateThank you rod for everything... I told my buddy to bring his spare key with him so we could try it before we went through another day of testing. Put in his spare key and it fired right up. So apparently his key went bad...It wasn't the inertia switch as I put a new one in today and tried the old key and that still didn't work. Crazy your ignition key can just go bad, Never heard of such a thing until now. However he did say he thought he could do the pump change by himself being I made it look easy... lol

I hope this thread will help other ford peeps! Good luck

If he has two working keys, he could attempt to reprogram the now bad key. Or, he could buy a new key, have it cut to the right pattern, then program it as well with the two working keys. The procedure is outlined in the owner's manual. Unfortunately, if he doesn't have two keys that currently work, he'll have to go through a locksmith or dealership to have another key made and programmed.

Keep this in mind with your Blazer as well, I imagine it uses a similar system. Years ago GM had the VATS system which used a resistor pill in the keys. It wasn't all that uncommon for the resistors to change in value and cause a no-start condition. I'm not sure what year GM transitioned to transponder keys, which would be similar to the transponder keys used by Ford.

-Rod

If he has two working keys, he could attempt to reprogram the now bad key. Or, he could buy a new key, have it cut to the right pattern, then program it as well with the two working keys. The procedure is outlined in the owner's manual. Unfortunately, if he doesn't have two keys that currently work, he'll have to go through a locksmith or dealership to have another key made and programmed.

Keep this in mind with your Blazer as well, I imagine it uses a similar system. Years ago GM had the VATS system which used a resistor pill in the keys. It wasn't all that uncommon for the resistors to change in value and cause a no-start condition. I'm not sure what year GM transitioned to transponder keys, which would be similar to the transponder keys used by Ford.

-Rod

You are correct when I had to replace the transmission in my blazer I had the battery disconnected for a week and had to relearn the security when I was done. It sucked being I wanted to start the darn thing and had to wait 30 minutes to go through the relearn process.