Hot Starting problem '95 Explorer

[sstocker31]

Hi guys and gals,
First post here, and as I have learned over the last couple of days browsing, you have a great venue here for the DIY person.
Now on to my issue, I'm working on a '95 Explorer with the 4.0L. She says it will not start in hot weather conditions after several short shopping stops....dead in the water for an hour or two. She is not very good at explaining what is going on but it sounds to me like the engine will crank over but won't start.
Now i'm about the tenth guy that she has taken this vehicle to over the last two years, and pretty much every bolt on item has been replaced....i'll list them

new rad cap/ coolant flush
new battery
egr sensor
egr valve
spark plugs and wires.....twice
thermostat
fuel filter
fuel pump/ filter again
airfilter
new manifold o rings
new maf sensor
ignition coil
new starter
spark plugs...3rd set

Plus a bunch of other stuff that isn't related to this problem, she has poured way to much money into this car, but it's all she can afford.....I just want to finally fix it for her

And the problem still persists....

I've gone ahead and tested the battery, cleaned the battery posts and terminals, cleaned all visible ground connections, checked fuel pump, PCM,WAC relays, checked the charging system, cleaned the air temp sensor (quite dirty), cleaned the idle air solonoid (again quite dirty and the felts were pretty much plugged....replaced those), Sort of ruled out the neutral safety switch,
and tested the coolant temperature sensor......now when I did this, at operating temperature, the sensor was pretty much bang on with the resistance values posted on a chart here on the forum, when I tested it cold (68* this morning and yesterday morning) it was like I had an open circuit.....
not at the 37.3 K ohms it should be.
Is there a remote possibility this could be the issue?? It doesn't seem to me that it would cause a hot start issue as it works fine at hot temps.

I'm grasping at straws here, anything else I should look at? Any info you could pass along would be helpful....thanks

 

[NorCalMike]

I personally would start at square 1 and make sure its got decent compression and maybe even do a leak down test on it. And do the compression test with the engine cold. It could have a cracked ring that's sealing up when the engine is warm. Just a thought.

 

[Explodr94]

In my past problems with hot starts, it generally tended to be the solenoid on the starter. I would check the positive cable for corrosion at the starter and the solenoid connections. The blade style connector has been corrected in the after market with a connector and shrink wrap.

 

[bobflood]

Given all that has been done, and the fact that the coolant temp sensor is bad at some temps, I would replace that sensor. Good luck.

 

[sstocker31]

Thanks for the replys guys....It's got a new starter and solonoid on it, so I don't think thats the problem, Seems to run fine when both hot and cold, so I don't think it's something major. I am going to replace the temp sensor, then give the car back to her and see if it does it again.....if it does happen again I'll revive this thread.

Thanks for the suggestions

 

[sstocker31]

Man....do I feel like an idiot.
It dawned on me driving home tonight, that I was selecting the 20K ohm position on my meter, and the resistance I needed at room temperature was 37.3......DUHHHH!
When I selected my meter to the 200K scale it tested 37.0 pretty much bang on.
Oh well, I guess I can rule that out now.