1994 Explorer electronics question

My 1994 Explorer Sport would not start even though plenty of cranking power to the starter. Simply would not fire a single cylinder. Towed to the shop,
they replaced the AC relay and it now works fine. Does this make sense? I had experienced the no-start problem two or three times before and managed to get things to work by backing the key all the way, three times, thinking it would reset the computer. What does the AC relay have to do with the firing the spark plugs?
Thanks!
Wayne
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On Wed, 03 Aug 2005 17:34:36 GMT, "Wayne Lundberg"

Makes no sense to me. Are you sure it was the AC relay they replaced and not the fuel pump relay? I think they both sit next to each other. It's also possible the yanked the AC relay and put a new one in and then it started and they said "ah, that's it" when all that happened was they jarred the old fuel pump relay when the replaced the AC relay and that made it work again (for a while). If my memory is correct, the relays are interchangeable (ac and fuel pump) so if it does flake out again you could try swapping them.
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wrote:

---snip---
The relay they took out has a label "A/C relay" or something to that effect, so I am assuming that's what they changed. But thank you, thank you, thank you for the suggestion to swap out the relays if the problem persists. Are they the ones on the fuse box under the dash?
Wayne
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On Thu, 04 Aug 2005 16:40:37 GMT, "Wayne Lundberg"

No, I believe they are in the engine compartment along the passenger side fender. There is a fuse block there (it has a cap you have to take off to see the fuses and they are large fuses, not the little ones like the inside fuse block). The top of that fuse block, with the fuses in it, detaches from the bottom and comes up revealing the relays. This is from memory so it may be a little different but that should put you in the ballpark.
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wrote:

Thanks again Ashton, I checked the fuse box, it's where you said it would be. And looks like there is a new relay in the a/c slot and not the fuel pump. Which means I should get a new relay and have it handy for the fuel pump!
Once the engine starts, is there a mechanical device that pumps the fuel or is it always on electric. Meaning that it could fail any time I'm driving on the freeway? Or is the electric just for starting?
Wayne
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The fuel pump on your Explorer, just like on most other fuel-injected vehicles is located inside the fuel tank and operated by an electric motor. Once the motor fails (or has no power), the engine stops. Actually, it's a good thing. A shock-activated cutout switch disconnects power to the pump and prevents a fire if you ever get in an accident.

or
on
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Weird! On three occasions I cranked to start the engine and nothing happened. On the first two I backed the key three times thinking I was resetting the computer and it started right away. On the third, I had to have the SUV towed to the mechanic. Who replaced the a/c relay and all is well. But I'm not so sure.
What I'm reading from Happy Traveler and Ashton is that the fuel pump relay may be the cause of this. But I have not had a single stall while running, and I have over 144,000 miles on the vehicle!
So... I am assuming the relay and fuel pump motor are OK, but the reason I could not get it started is due to some other, as yet unidentified, and potentially 'lurking' problem???? In the computer? Signal to fire sparkplugs? Because on cranking (on those three times it failed to start) I did not get a single explosion. Dead, as a doornail can be dead.
Any ideas what I should look for, or do the next time this happens while at a way stop in the middle of the Nevada desert?
Wayne

motor.
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