Truck Doesn't Start When Warm

Hello group.
My friend's 1994 Ford Ranger doesn't start sometimes when it's warm. After driving for any amount of time, the engine will turn, but it
never starts. It will eventually start once the engine cools down. She has had no problems at all with cold starts. The warm start is only intermittent, though.
Mechanics have shown their lack of experience by blowing hundreds of dollars in repairs that have solved nothing. They're helpless because it never fails by the time a mechanic gets involved.
I already have a solution in mind, but I am looking here for additional insights from your collective experiences.
I plan on replacing the coolant temperature sensor. This sensor could be giving the fuel injector a cold start condition when the engine is actually warm. That would cause the fuel mixture to be wrong, and subsequently the engine won't start.
Does anyone have any other ideas?
Thank you so much for your input.
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It COULD be doing a lot of things. The ECT COULD be bad, probably not to the effect you are saying, but the right way would be to go to a competent technician that will actually test it when they experience it. You can't fix anything that isn't broke, doing anything when you don't experience the problem is a guess at best. All you propose to do is throw money at it yourself. A good Ford dealership will have equipment that can record what is going on when the symptom occurs.
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If the sensor was that far off a code would be set, most likely not the problem. Install a fuel pressure gauge and check for fuel pressure when the event happens. Check for spark when the event happens. It will be more than likely a ignition system problem or primary fuel system.

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Will Wise wrote:

fords.. it covered all the cars and most of the trucks.. i have a 93 taurus and it covered it, but i never needed the repair involving the ignition...it seems that the heated up engine also heated up the ignition module and it failed... it was like a $250 repair/replacement that they agreeed to pay for, dont know if it covers your car/truck and it was a few years ago...so it might not be included in this suit any longer???? the heat of the engine along with the heated up module might be causing the module to have internal resistance and it might be failing... when it cools down and the mech. looks at the truck then he finds no problem as it no longer has resistance... give it a try and see if you can find the problem... hope this helps.
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The symptoms you mention does indeed indicate a problem with the Temperature sensor. Check to make sure the wires are connected at the sensor, or that there is no broken wires/open circuit. If all is well, do this simple test. Disconnect the harness and measure the resistance across the two terminal of the sensor. The reading should be about 42,000 Ohms when cold, at about 60 deg. F. Reconnect the harness and start and warm-up the engine to 180 -220 deg.F.. Shut off engine and disconnect harness and re-measure the resistance, it should be about 3,000 to 1,800 Ohms. If the readings are off, you probably have a bad sensor. When you replace the sensor, buy the genuine Ford replacement part. This is one of the few times when I will vote for a genuine Ford parts.

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Why not just check the voltage? It's easier, .6 volts is 195 degrees. Readings much different then that when hot would indicate a problem. I seriously doubt that's what's going on here. Bob
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I am 98.9% certain the Temp. Sensor,or, an associated Temp Sensor is at fault..

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What makes you so sure? The OP didn't mention any codes... I don't think he even said which engine he has. The only way we will ever know is if he checks it and reports back but I'm about 99% sure it isn't a temp sensor. In the mid 80s a bad sensor could have cause it but not likely on a 94. Bob
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OK Bob, lets wait and see. I have seen this same problem on Fords since 1989, and up to today. With the new improved engine management computer, a bad sensor, or a broken circuit, on a hot engine will read with a high resistance indicating a cold engine, the injectors will spray gas as if it were a cold start. That will flood the engine and it will not start until it cools down. Mr. Will Wise, would you please report back to the NG when you obtain a fix on this problem. Thank you.

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The Ford processor also know that the value from the sensor, and based on the values from it's other sensors puts in the correct value for the bad one and sets a code. The engine will run. The processor will be in failure effects strategy. The problem will most likely be ignition or primary electric side of the fuel system.

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Lets just wait for Mr. Will Wise to report back to the NG when he obtain a fix on this problem. Since neither of us has seen the car first hand, it is pointless for us to speculate, OK. Thank you

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Not a bad idea too wait, but it's more speculation on your part.

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FMEM or Failure Management Effects Mode is Fords answer to the question of how to keep stupid shit like a failed sensor from leaving someone stranded. The engine may run poorly, but it will still start and run. Bob

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If this can help, I had a similar problem on my 87 Town Car, it would start when cold , but not when warm......it happened to be the TFI, after a while running, the ignition circuit would heat up and cease working, I replaced the module and it was fine afterwards......
good luck

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