1993 Explorer XLT fuel pump issue.

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Shorty:
No problem, I did check in the fuse (distribution) box and there are 3 relays interconnected by a red wire, and they all had power, that was my original reference.

I will go look for all 3 red wires coming into the computer. Can I just pull that plug off and check wire from that end, as on the first check I just poked the wire with the test
lead?

Will also attempt that eec test plug fuel pump situation you described and let you knw.
Thank You

 

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EEC TEST Connector

Shory:

Am excited, did the fuel pump on the eec test connector and the relay clicked and the pump ran. I dint see if it cycled or shut off after 5 seconds
but it runs when you close the two slots on the left side of the connector.

Maybe we are getting some where. Thanks.....Keep up the good ideas!

 

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Test Connector and Fuel Pump

The pump will run if you short the pins in the test connector, relay on fuel pump clicks. I tried to start it with this hooked up but no start. It still will not click the fuel pump relay unless you short it. Should I pull the PCm from the kick panel and check wirng connections in that big plug that fastens to it?

 

[MrShorty]

So the fuel pump circuit is intact. It is looking more and more like there must by something wrong with the main PCM: It isn't getting power, It doesn't have good grounds, or something internal. The next thing I'd do would probably be to get access to the PCM and see if it has power (three leads) and good grounds (also three).

 

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PCM Power

I have completed testing the "3" power leads on the pcm plug. 1-37-57 and they appear ok. Testing the ground circuts 20-40- 60, seem ok also.

I am assuming I have the right pcm pinout diagram. There were no pin numbers on the plug that I could find. I had a guy tell me to check the DFPE
sensor as he has seen them short out and shut down the whole system. But I cannot find it. I also cannot find the egr valve. Which the DFPE controller is suposed to be close to it. He showed me a new one, and it has two vacumn line and an electrical plug in it. And mounts with two bolts.

I left the computer cable out of the controller and hooked the neg cable back up so I could check some other voltages, and when I hooked it up something
whirred, like a motor, thought it was the fuel pump kicking back in but it was
a sound like a sewing machine running for a few seconds. Any idea what that was? Also the computer cable was unhooked at the time.

I reconnected the plug to the computer and put the neg battery cable back on and same story, no whirring, but no cel or pump 20 second activity. I attempted to check the tps sensor for 5 volts but I
I got were goofy readings like 444, using a digital meter should I used an
analog meter?

The VIN Number for the Explorer is 1FMDU 34X4 PUA4 6265

Controller is ECCIV EF1 MA46G BAT 1
F37F 12A650 -ZB
63EMG 46A15

 

[MrShorty]

A bad DPFE will usually leave some codes in the computer. Have you tried pulling codes to see if you can even talk to the PCM.

Goofy readings on the Vref circuit at the TPS or elsewhere further suggests that something is up with the PCM power/ground or the PCM itself.

And, some '93's don't have EGR systems. Based on his experience, I might search for it and try unplugging the DPFE to see if anything improves, but, if you can't find the EGR system, it might not be there to find.

 

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TPS Voltage

Do I need to use chassis ground or is there a ground in the connector terminals? Referencing the goofy readings from the previous email.

Also I used a test light when I had the B+ coming from the battery to test the grounds with and I touched the test light to the case of the computer and it did not light. I noticed I believe #20 is called case ground. So should
the case be negative or not connected at all? The test light is LED and I guess wouldnt pull much current if it did make connection.

I have not been able to get a code reading, or according to the reader which is supposed to show a diamond or a square when it hasa connected to the computer, I have had no proof of connection. It is a 4 wire reader from Oreillys, I guess it is the right one, but it only connects to 3 terminals in the
ecc plug and the gray plug (extra wire) plugs on the side of it.

Appreciate your help.....Thanks

 

[MrShorty]

I noticed I believe #20 is called case ground. So should
the case be negative or not connected at all? The test light is LED and I guess wouldnt pull much current if it did make connection.

I'm not sure if the case is grounded or not. Usually when I've checked the grounds, I will backprobe the ground at the PCM connector with the positive lead, then put the negative lead of my meter to ground (to the negative battery post, if possible). If the meter shows any significant voltage drop across the ground wire, that indicates a poor ground. It should be noted that at least two of the grounds are wired straight to "pigtails" on the negative battery cable, and these sometimes corrode through.

 

[mawrazen]

I want to simplify this if I can.

On my 1994 EX the fuel pump is hardwired to the fuel pump relay by a green/yellow wire. I assume it is the same color on the 1993. Check that wire for voltage (key on).

I had a similar problem and at one point I hardwired the fuel pump to the positive terminal on the battery just to get it to work. I had to pop the hood everytime I stopped to disconnect it. LOL

I would test the fuel pump by energizing the fuel pump circuit manually. (You will hear the Fuel Pump running if it is working) This could be done by removing the fuel pump relay and running a jumper with a 30 amp fuse from the battery to the socket of the relay. Or, just cutting it, and splice on a short jumper. This is what I had done out of desperation when left Found On the Road Dead.

Good Luck!

 

[Deleted member 128963]

I hate to interrupt your train of thought here, but I just had the fuel pump relay go bad on my 1994 X Limited. I got a new relay and it was intermittent.
After closer inspection, I noticed that on this relay and the others, i.e. the PCM relay and the ABS relays, sometime in the past there had been overheating which actually got hot enough to melt the yellow plastic covering some of the sockets and looking through the slots at the terminals, the terminals were discolored. This led me to believe that maybe some of the terminals had lost their temper, (not in the same way I lost mine), but that the terminals were no longer strong enough to make a good solid contact with the blade of the relay. One of the blades of the bad relay was also discolored and when I opened it up, the relay contact was burned. As a temporary fix, when I installed the new relay, I took a pair of pliers and CAREFULLY twisted the 5 terminals just a little bit so that they were slightly misaligned with the slots of the socket. With that small twist, the relay has worked every time, I believe due to some increased tension between the relay terminal blades and sockets.
I have been investigating how to remove the Power Distribution Box to see if the relay and fuse sockets in there are removable and replaceable as new sockets would be the best fix. I can unlock the locks that hold the box in its mount and can lift it just a little, but it seems that the harness coming from the front of the box is preventing it from lifting free from the mount. This harness goes behind the starter solenoid and around the front of the vehicle.
It is necessary to remove the solenoid to get enough freedom of the front portion of the harness to be able to lift the Distribution Box or have I missed something here?
Appreciate any light you can shed on the subject.
Bill

 

[mawrazen]

I also have burnt slots on the Fuel pump relay. I like your idea of refurbishing the slots. You have now solved my problem. Thanks!

PS. -The Power Distribution Box is removeable by using a screwdriver on the flanges that clip the box to the frame. You need to push the flanges away from the box while pulling up, then while holding the one side above the now released lock, disconnect the 2nd flange. This gives you access to the underside.

 

[Deleted member 128963]

I can release the tabs and get the box to lift up a little from the mount, but it seems take considerable force to lift it further than that due to the wiring coming out of the front end of the box. That forward wiring harness runs behind the starter solenoid and there doesn't seem to be enough slack to allow the box to lift completely off its mounting point so that I can gain access to the bottom cover. Maybe the harnesses are a little different and some have a bit more slack. Just don't want to force it and end up with more trouble.

 

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billmnfl:
The box has two tabs on the left side. Press them in and box will lift up, There is a bundle of wires on a tab that is hooked to the rear of the box. Snap it loose and the box will move upwards about a foot. But it is still tight at the front of the vehicle as the
feed from the solenoid and other wires come in from the front, but it will give you enough room to press the tabs and remove the bottom where you can gte at the underside of the relays.

 

[Deleted member 128963]

Yep. Got it. Thanks for the help.

Bill

BTW, I found a box out of a 92 XLT. It's in great shape. No burns, no damage. $25.00. Can't beat that.

 

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AC/WOT Relay

I am still working on the Ex. Today I found that the AC/WOT relay is not clicking when you turn on the key. I has lost the AC about a year ago and thought the clutch coil was bad, so I dug deep into it today and foiund that if you put B+ to it and ground with the connector off, it will kick in and hold the clutch solid.

So my poiint is, I guess, since I lost that months back, and now can't get the
fuel pump to kick in, any ideas? I checked the red wire on one of the injectors and had 12 vdc. Dont have a noid light yet, they want $50 a set here so waitng to find a cheaper set. Unless there is a way to make one.

Finally got the Check engine light bulb out and tested it and it is ok. So I put the dash back together.

There is a green relay looking thing on top on the glove box, any ideas as to what it is?

Also found that the Fuel Pressure Regulator had no vacumn hose on it so I got one and hooked it back up.

And the kicker, it seems that the wiring on the crank sensor is brittle and oily as I have discovered that the valve cover gaskets (I think) have beend leaking as both sides of motor have oil on them. It would use a quart of oil evry 500 or so miles, but never saw any leaks, nor did any place that changed oil for me ever mention.

Hope some one has had the above and can tell me which way to go next.

 

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Crank Sensor Wires

Ok, I cleaned the crank sensor and separated the brittle wires, and spread them apart and sprayed carb cleaner in the intake and the vehicle will run for a few seconds. Dod ot twice and both times, it ran smooth. But died. Am investigating for a used PCM I guess from a junk yard, or should I waste time that way? Still working on the questions from the thread before this one.
Any help appreciated.

 

[BWTGUY]

Here are the FORD manual pages that may help. These are for a 1992 EB and should work on almost any 1st Gen fuel system.

Electric Fuel Pump System

The Electronic Fuel Injection (EFI) system uses a fuel tank, and a fuel pump and sender assembly. The fuel tank on the Aerostar, Ranger and Explorer have an internal pump cavity where the fuel pump and sender assembly rest. This design provides satisfactory operation during extreme vehicle maneuvers and steep vehicle climbing with low-tank fill levels.

The fuel pump is mounted on the fuel sender assembly inside the fuel tank. This assembly includes a check valve which is in the outlet of the fuel pump. The function of this valve is to maintain pressure in the system after the vehicle is shut down. The pressure retention helps prevent hot starting problems. This pump is capable of supplying 60 liters (16.9 gallons) of fuel per hour at 310 kPa (45 psi). The fuel pump has an internal pressure relief valve which limits the maximum fuel pump pressure to 850 kPa (125 psi). This only takes effect if there is a system blockage, causing system pressure to rise too high.The system pressure is controlled by a pressure regulator on the engine.

The fuel pump is protected at its inlet by a nylon pickup element. This nylon element filters dirt and contaminants which could plug or damage the internal pump components while at the same time allowing passage of small quantities of water which may accumulate within the fuel tank sump.

The electrical system has a fuel pump control relay controlled by the Electronic Engine Control (EEC) module, which provides power to the fuel pump under various operating conditions. When the ignition switch is in the OFF position, the contacts of the EEC power and fuel pump relays are open.

The test tree is as follows,

A4 ELECTRICAL CIRCUIT CHECK


*l Inertia switch open? (Reset switch as required)

*l Wiring at fuel pump/tank connector loose or open?

*l Fuel pump ground connection at chassis loose or defective?

*l Improper fuel pump relay operation (should operate when FP (test) lead is grounded with ignition key in RUN position).

*l EEC relay not operating if fuel pump relay doesn't operate?

Yes
SERVICE all electrical problems and RETURN to step«A1».

No
If no electrical defects have been found, and pump still won't run, REPLACE pump and RETEST per step«A1».

I'll monitor your issue on the chance I can help. Don't give up, we've all been there.

 

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FP Test lead

*l Improper fuel pump relay operation (should operate when FP (test) lead is grounded with ignition key in RUN position).


This test lead is it the one on the eec connector. If I cross it and the one to the left of it, the relay clicks and the pump runs. but vehicle wont start that way. The pump is loud, lot louder than it used to be, like it is under high pressure or something. Could it be bad and causing the FP relay to stay open?

Will use your list of tests tomorrow, dark here now, but I do appreciate any and all help I can get.

 

[BWTGUY]

Be advised if you reverse the leads on a DC motor, it will run backwards! Make sure that the connections in the test write-up are as indicated.

 

[MrShorty]

I has lost the AC about a year ago and thought the clutch coil was bad, so I dug deep into it today and foiund that if you put B+ to it and ground with the connector off, it will kick in and hold the clutch solid.

So my poiint is, I guess, since I lost that months back, and now can't get the
fuel pump to kick in, any ideas?

The AC WOT relay wiring is the same as for the fuel pump relay: power from the EEC relay to coil side then to PCM which controls the opening/closing of the relay by supplying ground. It's hard for me to picture exactly what you put B+ to at the AC WOT, but it looks like maybe the PCM isn't grounding the AC WOT relay either for the AC system.