I have a `95 Explorer with the 4.0L push rod engine and auto trans. It has 187K miles. The last three times that I started the engine it ran rough for a brief moment, but smoothed out by the time I had put it in gear.

Today it continued to run rough and when I tried to give it some throttle it died and would not restart. I have checked the air flow sensor and it tests fine for the sensor and the connector having correct voltage. I tested the connector for the crankshaft position sensor and it has the correct voltage, but I have not tested the actual sensor, as I was unable to get the connector off with the limited tools I had with me.

Finally, I also tested the throttle position sensor and found –1.08 volts in the closed throttle position and rising to –3.5 volts at the full throttle position. Shop book said the voltage should have been +1.5 and rising to +5.0. Are the values of my readings indicative of a problem with this sensor or is the fact that I had negative voltage readings indicative of a problem?

Any other suggestions as to what to look for would be greatly appreciated.

 

You prob had the wires on the wrong terminals...Sensor is fine. Try flooring it to clear it out and see if it'll start. Check for spark???


Dick

 

Have you checked the more obvious things like battery/alternator/starter/cables-to-all? IAC may be responsible for rough conditions.

 

Any codes present? If not, I'd suspect a bad fuel pump, especially at that mileage.

Check the fuel pressure at the fuel rail schrader valve.

 

you need to check for spark, and fuel pressure. need to figure out which system is failing. then we can lead you in the right direction

 

It ran rough for the last three times, then ok after a while- I would bet on intake manifold seals, they contract when its cold and they let additional air in, when they warm up they close the gap so it would run ok. Maybe they have really given up now!
If so and you have a code reader- confirm this codes, are p-0171, p-0174.
This is a link to a step by step with pictures on the fix!
http://www.explorerforum.com/forums/....php?p=1555157
Good luck and let me know how you get on.

Spirit

 

Thanks for all the responses.

At this point I believe thelonerangerxlt has the winning ticket. I went back this morning to where the truck was left and continued my diagnostic work. Focusing on the fuel pump I found no sound of it running, good fuse and relay, no tripped roll over sensor under the dash, and no pressure in the fuel rail.

Had the truck towed back to my home. I will check a couple more items, but I'm fairly sure I'll be lowering the tank tomorrow.

Thanks again to all.

 

Sounds like you've found the culprit, Mchild.
Glad we could help; let us know how it turns out.

 

Before putting a pump in, make sure that the wire on the bottom of the inertia switch is firmly connected. It's a bit of a long shot, but much easier than putting a FP in. While you are there, use a test light to confirm that you have power to the inertia switch (with the key ON). If you don't, then the problem is between the ingition and the inertia switch, which rules out the FP.