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'94 Explorer Wont Start when Hot!

WGPu

New Member
Joined
July 6, 2007
Messages
3
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City, State
Knoxville, TN
Year, Model & Trim Level
'94 XLT
Hello All,

I'm new to this forum and need some help.

On hot summer days, if I drive my Explorer for a while (more than a few mins.) it wont start after a short stop (gas, store, etc.). It cranks well, but wont turn over. Just had the fuel pump and filter replaced along with plugs and wires. Problem persists.

I've looked around on the 'net and this seems to be a common problem.

One guy on the '95 and up forum pulled his neg. batt. cable for a few mins. to "reset the computer" and the vehicle started. I tried this and it did not work initially. Tried starting it again after a min. and it did start.

What is real interesting, though, is this. On another web site, a guy with the same problem noticed that if the "Check Engine" light did not come on when the key was "On", the vehicle would not start. If the "Check Engine" light did illum. when key was in "On", the vehicle started! That's exactly what's happening with mine!

Any answers? Thanks.

B.
TN
 



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Start with.....
I have a '94 XLT that had intermittent starting problems last year. On an infrequent and random basis the engine would crank fine but doesn't catch. After wiggling the wires and tapping on the fuel tank it would start, but eventually I was told the fuel pump was failing. I knew it was 12 years old so I had it replaced and everything's OK for eight months, but now the same problem is occuring. When it's working, you can hear the whine of the fuel pump when the key is turned. When it's not, no whine so I don't think the fuel pump is getting power. Once the engine is running I've never had any problems, so I'm not sure it ever was a fuel pump problem. Sometimes it won't start, then after sitting for an hour it will. Any suggestions?

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Did you change the fule pump relay? My 94 XLT (with 180K) had a problem to start right after the engin was off for 10 to 20 minutes, when the engin was cool, it can start again and runs fine. I traced to the fule pump relay and bought one from AutoZoe for $6.00 and have not have any problems since.

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My 95 Explorer would occasionally crank but not start. Occurred ONLY when engine was warm -- never on the first start of the day. After waiting anywhere from a few minutes to 2 hours, the engine would then start normally. Happened between once every few months and 2 - 3 times a week, and VERY intermittently. When I drove it to work and then it sat for several hours, it would always start. When I monitored the EEC-IV codes, it would always start, of course. Finally took it to a dealer I trust and left it for 2 days so they could try to repeat the problem. They finally got it to happen and determined that there was no fuel pump pressure when the engine was in this state. They replaced both the Fuel Pump Relay and the EEC Power Relay. After these replacements, they could no longer duplicate the problem. This was almost 4 weeks ago, and I have not experienced the problem. It could just be the odds, or the relays may have been intermittent. Since it is a cheap repair you can easily do yourself, replacing these two relays would be my recommendation as a starting point.

Aloha, Mark
 






If the check engine light does not come on chances are the computer is not getting power, check for corrosion on the fuses, relays, and diodes in the power distro box under the hood.
 






I agree, sounds like a computer problem since it only occurs when you get no CEL upon startup. If you're lucky, it's just power as mentioned (although that's not always easy to track down).

Good luck.

Mike
 






Just something to try....

...in the failed condition, ground the fuel pump test terminal on the EEC TEST connector. The purpose of this terminal is to check fuel pressure without having to start the engine, but you could verify that the pump is running by putting a jumper wire between the lower right hand terminal and ground.

Something I'm less familiar with is the DIS module. It should be mounted just forward of the battery. The module is what tells the DIS coils when to fire. I believe it does this by processing the PIP signal from the crankshaft postition sensor. Someone smarter than me will have to help you more in this area.

That said, I'd do the easy and cheap stuff (already mentioned by others) first.
 






OK, I read your post again.......you have an elec. problem......duh.

But, I assume that you already checked the easy stuff. Like at the battery: connectors could be loose, corrosion of the terminals, broken battery post, check wires and ground. Clean it up and check for full voltage on the battery. Battery cables have been known to corrode from the inside, even though on the outside, the plastic sheath may still look intact.

Next, go through the ignition circuits, fuses, connectors, wires, relays and don't forget to check the wires to the switch itself.

Then move on to the computer.

Aloha, Mark
 






It also never hurts to pull the codes. You might get lucky...
 






Thanks- The Answer!

All,

Thanks for all the responses.

Mark,

It looks like you were right in your first reply. I changed out the Fuel Pump Relay and the EEC Power Relay and the problem appears to have gone away.

Take a look at this very interesting diagnostic article about a similar problem in a Lincoln.

http://www.samscars.com/mage1.htm

Thanks again.

B.
 






always start with the easy to check stuff first.

glad you are good to go.
 






'94 X won't start when hot!

All,

Thanks for all the responses.

Mark,

It looks like you were right in your first reply. I changed out the Fuel Pump Relay and the EEC Power Relay and the problem appears to have gone away.

Take a look at this very interesting diagnostic article about a similar problem in a Lincoln.

http://www.samscars.com/mage1.htm

Thanks again.

B.


This is a Very interesting article, don't ya' think guys? I think it is, there are prob'ly lots of these loose connection relays out there causing people headaches, ya' think? :)

 






Never, only on Explorers... :)

When I read the first post, I was thinking fuel relay, until the bit about no CEL on startup. Any ideas what would cause that? Would that be the EEC relay's fault?

Mike
 






Never, only on Explorers... :)

When I read the first post, I was thinking fuel relay, until the bit about no CEL on startup. Any ideas what would cause that? Would that be the EEC relay's fault?

Mike

If I can trust my Haynes manual diagrams, it looks like the PCM relay, when energized, supplies power to the contact on the fuel pump relay. When a ground is supplied through pin 22 of the PCM, the fuel pump relay is energized and power (supplied by the PCM relay) passes through the fuel pump relay and splits. One wire powers the fuel pump and the other applies power to pin 8 of the PCM. I don't have a pinout diagram of the PCM, and Haynes doesn't label this pin to say what it is. I suspect, however, that the lack of power at pin 8 is why he had no CEL.

My Haynes manual covers 1993 to 2005 Rangers and the diagram is shown for the 1993 4.0L. The drive train on my Ranger is pretty much identical to the Explorer. The wiring diagram was a little better than my Explorer manual.

Excellent thread and link. Thanks for the follow-up
 






You're Welcome

I'm glad you all found the article I linked interesting.

B.
 






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