Intermittent Start - Seems to be heat related

[joepaigejr]

2002 Explorer XLT, 66,000 miles

It has happened twice in past 3 weeks (wife basically drives only on weekends).

The last time (yesterday), my wife went to the mall (I have already told her her truck is tired of going shopping, unless it is to the Harley dealer ) for and stayed for about an hour. She left the mall, drove for about 15 minutes, turned off the truck for about 3 minutes for an errand. When she got back in the truck she said it would not start. She called me and I told her to wait for 20 minutes and call me back. Of course that did not work, so I went to pick her up. (She was about 5 minutes away.) I took my test meter with me. The battery was at about 12.43 volts, and dropped to 11 volts when trying to start (with jumper wires connected to my truck). It sounded to me like their was no fuel reaching the injectors.

We went to dinner and came back. Her truck started right up.

From searching the net, it appears to be either:

• PCM relay
• Fuel Pump relay
• Battery to starter cable

How do y'all recommend I diagnose and fix her truck? (I have also noticed twice that her truck cuts off sometime when backing out of the driveway. It starts right back up. She said this is not unusual, but does not remember when it started happening.

Thanks!

 

[BrooklynBay]

Does the starter turn over? Are the battery cables clean? Do you hear the fuel pump prime when you turn the key to the accessory position? Did you check the fuel pressure?

 

[aldive]

I would check the fuel pressure first.

Good luck .....

 

[joepaigejr]

The starter turned over. The cables are clean. It just seemed like it would not start because it was not getting any gas. I believe I heard the fuel pump prime, but cannot be sure. I did not check the fuel pressure. Do I just hook a fuel pressure gauge to a connection under the hood? Are you two thinking more about the fuel pump relay being bad?

Thanks

 

[BrooklynBay]

It could be a bad fuel pump relay, bad PCM relay or a tripped inertia switch.

 

[aldive]

Do I just hook a fuel pressure gauge to a connection under the hood?

Yes, it connects to a Schrader valve on the fuel rail.

Are you thinking more about the fuel pump relay being bad?

I reserve comment until I see what the fuel pressure is doing.

 

[joepaigejr]

It could be a bad fuel pump relay, bad PCM relay or a tripped inertia switch.

Are their diagnostics somewhere on the net, or do I need to get a Shop Manual?

Thanks

 

[joepaigejr]

I reserve comment until I see what the fuel pressure is doing.

Roger on the valve. I will report back after I pick up a fuel pressure gauge from Harbor Freight.

Thanks

 

[BrooklynBay]

Start with the inertia switch. It should be a closed circuit. A bad PCM relay will cause the check engine light not to illuminate when you turn the key to the accessory position. A fuel pump relay could be jumped with a wire to see if the pump starts.

 

[joepaigejr]

Start with the inertia switch. It should be a closed circuit. A bad PCM relay will cause the check engine light not to illuminate when you turn the key to the accessory position. A fuel pump relay could be jumped with a wire to see if the pump starts.

Are there diagrams or locations of these parts somewhere on the net?

Thanks

 

[BrooklynBay]

The inertia switch is behind a kick panel in the vehicle, and the relays are under the hood. Check Autozone's website for more information.

 

[joepaigejr]

All,

I take it all of these diagnostics are to be performed while I am experiencing the problem - right?

 

[aldive]

You can check the fuel pressure whenever.

 

[len730]

My 94 Ford Explorer 4X4 started have a intermittent start problem. Having years of mechanical and electrical experience I decided to track the problem down. I had a few things that I needed to know; How common the problem is? What have others done to fix the problem? What expected fixes didn't work? As I researched the problem I found no one seemed to find the problem, even dealerships. I was on my own. No long message telling you how I found my problem. You don't need to hear about me tooting my own horn. Here is what I found.

In the fuse/relay box, on the passenger side, there is a relay that controls the fuel pump. It also enables the electronic ignition to allow the car to start. The hot wire that supplies 12 volts to these functions comes in on a single wire. It is heavier than most. It is soldered into a female spade terminal that is mounted in the fuse box. When you plug the relay in, one of the contacts on the relay pushed into this terminal. It has gotten hot and corroded to the point that it only makes intermittent contact.

The way I fixed it was to cut each wire under the fuse box that goes to the relay. I decided to cut one wire, put a terminal end on the wire then plug it into the relay. I did this for each wire that went to the relay. DO NOT cut all the wires at once, or you may get them mixed up. When done I put the fuse box over the relay, mounting it back in place.

It has been 7 months since I did this and it has not failed, even once. I'm not afraid of letting my wife drive it again.

While I don't believe this is a universal fix for everyone's intermittent starting problems, I believe it should fix most. Not even the dealers are aware of this terminal problem, in the fuse box. Everyone just assumes that when the relay is plugged in, it is making contact.

Hope you find this information helpful and if it works for you, send me a little note saying "Thanks", at len730@juno.com. I would like to see just how many I have helped.

Leonard Morgan

 

[Cobraguy]

Brooklyn, are you thinking the inertia switch is intermittent?

 

[BrooklynBay]

It could be anywhere in the circuit. The only way to tell is to start troubleshooting as soon as the problem occurs.