What, you didn't like my answer? Code 92 is circuit open, battery to PCM. Which in english is battery through the relay. The ECM monitors the voltage just after the relay to see if it has switched. This means

1. The relay is bad
2. The fuel pump fuse is bad or there are bad connections to the fuse or there is no always on power to the fuse.
3. There is a bad connection from the ECM to the relay coil.
4. There is a bad connection from the ECM 12V to the relay coil.

How did you get so lucky to have an intermitant and get a defined code. If you have swaped the relay, you may have done the wrong one. Look for any unusual signs on the contacts of relay or the fuse.

The tach runs off the computer (crank sensor). there is no connection to the ignition coil.

 

The code was stored in the continuous set of codes. I appreciate your response and answer, I'm just trying to figure out how these things work. There are two codes for secondary fuel pump failure - 95, which is PCM to ground and 96, battery to PCM. I think mine was a code 96, but I can't remember for sure.

I'm just asking more questions to try to pinpoint the exact cause of the problem, not to discount anything you have said. I just don't want to end up throwing parts at it until it is fixed. The tach runs off the negative side of the coil, I don't have a crank position sensor. I took the fuel pump relay out the other day, and just stuck the same one back in, and I haven't had any problems yet, but the way intermittant problems can be, it could happen any time.

From the list of possibilities you list, I see 3 and 4 as most plausable. The only question I have about that would be where should I start looking? There's not that much in terms of wiring before the relay, but could the problem be after the relay? I'm trying to be sure I don't go out and buy a new fuel pump and that not be the problem. All the fuses are ok, but I haven't had a chance to look at that relay, other than taking it out and just looking at the outer terminals, which looked ok.

I don't know if I've seen an answer to this question so I'll ask again: would the relay just kick off after I've been driving 10-15 minutes, then kick right back in after about 10 seconds? That's what doesn't make sense to me, and what I'm trying to get figured out in my mind.

Thanks for your help, I really appreciate everything, even if I question it - I'm just trying to learn and to get this thing figured out.

 

Well, the 87's do not have a crank sensor. I don't know where that came from.
Yes the tach may get it's output from the "-" side of the coil output, but the coil is fired by the TFI module, which is triggered by the pick-up coil in the distributor, so if the ignition is firing, the tach will show RPM.

Have you checked the computer ground real good? It is usually grounded to the fender where the small wire coming off of your ground terminal on the battery is bolted up at. A bad ground can cause some crazy things.
I would replace the relay first. It is usually under the hood near the firewall on the drivers side. It is a green relay. The coil inside the relay could be breaking down and not holding the contacts together good enough.
Check the connections for corrosion while you are at it like mentioned above.
Jimmy

 

Sorry, the tach does operate off the coil. I answer so many Explorer questions I get a Brain Fog.

The computer monitors the voltage just after the relay contact. This allows detection of a bad fuse, failed or missing relay.

It could also detect an open impact switch or open pump by applying a small current to this point. This may be the code 95 ECA to ground. Basically there is no current path to ground and the circuit is open. I have found nothing to verify what this code 95 actually is. I design embedded computer systems and that is the way I would have done it. It would make sense that 96 is battery to and including the relay, 95 is everything after. So 95 could be an open fuel pump because of a stuck brush or bad connection at the impact switch.

 

Thank you so much, I understand what you guys are saying now. I wasn't quite sure how the fuel pump monitor code could indicate exactly that the relay was bad or if the fuel pump was bad, but now I have it pictured. I'll see about getting a relay when I get a free moment. I really appreciate all your answers, thanks again.