2000 Exployer SOMETIMES will not start

Have cleaned the battery cables? Tested the battery for a bad cell?

Does she park in the sun at school (and shade other times). Has she tried parking for the same lenght of time elsewhere and gotten the same problem?

Saying 'will not start' is very vague, will it not crank properly or does it crank OK, but not fire?

I think the OP needs to clarify a few points, but until then certainly cleaning the battery terminals (and testing the battery) is a good move. Can't hurt!

Yes, we need more info. But if we are supposed to guess then I'd guess it's turning the engine but there is no spark. And I'd guess the battery has one or two weak cells or bad connections. So that makes three battery guesses ;-)

My BAD The engine turns over fine. It just does not start. About 10 15min it will start and not do again. This happened now 4 days in a row.. Happens no other time. Wife does park as she has done for years at the same place on a little hill.

I had a guy check the gas pressure and it was 80.

Have you pulled Codes?

Even if there is no Check Engine indication, there will still be codes stored that might help to chase this down. If there IS a Check Engine indication, it is helpful to tell us this up front so we can suggest pulling codes before you throw a shopping car full of parts at the problem.

No Check Engine or Service vehicle light on.. A man told me turn the KEY on for a minute before you crank it.

Pull codes anyway.

Scan for DTC codes anyway, some (many) codes do not turn on the CEL.

This is pretty weird here I go. This 2000 has 90K Miles on the 4.0 engine.

Unless you find a pile of parts under the car that need to be bolted back on, ALWAYS pull codes before pulling your wallet, especially where you do not have a clear direction to go in.

Cars and trucks sold in the USA from 1996 are OBD II (On Board Diagnostics, Level 2) compliant, and the computer that manages engine operations and emission controls -- among a host of other vehicle systems -- stores codes that may or may not illuminate the Check Engine Light. If there is a code, odds are very strong that it is the key to whatever ailment has you wrenching today. There could be lots of codes, or just one.

If the car runs and drives okay, I'd strongly suggest writing the codes down and resetting all of them, then driving until the symptom returns, and pulling codes again. Any code on the first list that is also on the current list is to be the target of your activity. This strategy is not bullet proof, but it works far more often than not, especially in cases where the symptoms are like what you describe -- the wife drives, parks, drives again and something goes awry, then everything is okay for a few days, then repeats.

Some AutoZone stores, (many parts stores with Loaner Tools) will let you use the scan tool for free. If you can't find a free scan tool, you can buy one for the cost of pullinig codes two or three times, and you will use the scan tool for a very long time because it can be used on ANY '96 or later car or truck sold in America. You can use the tool several times on your own fleet of vehicles, then sell it on eBay for more than half of what you paid, and this makes the tool pay for itself.

Pull the codes. Do not pass Go.