Hi all,
I have a 97 F150 4.2 automatic 2 wheel drive. While backing out of the driveway it died and would not restart. Tested good spark at plugs but installed new plugs and wires anyway since it was over due. Fuel pressure at rail registered 35 psi. Installed new crank shaft position sensor even though I didn't think it was bad since I was getting spark at plugs. Tested the camshaft sensor with multimeter and it showed 12 v with key on no crank red lead, middle lead drkblu tested 12v cranking and stayed 12v after cranking. I was unclear on testing the ground other than ohm test which I did and it showed good. After new plugs and wires installed which was the last thing I did still no start so I removed number 1 plug rechecked for spark and presence of fuel both were positive results.
Any help would be greatly appreciated
Thanks

 

Side note to this, when the new crank shaft position sensor was installed it fired up and ran for about five minutes then I shut it off and then I restarted immediately. Both times it took a small amount of throttle work to keep it running. After I shut it off the second time it refused to restart.

 

Crack the throttle 1/4 way and try again.

 

After charging it overnight I tried the suggestion to hold throttle at 1/4 but no luck. Just cranked with no attempt to fire. I then sprayed starter fluid directly into throttle while holding open. When I turned it over it tried to fire but it sounded as though maybe just on a couple cylinders and it popped or backfired through intake.
I realized I left mileage out of my initial post. In excess of 216,000

 

Assuming you have injector pulse, all that's left is compression and valve timing. I'm assuming things like air filter have been checked. Does the fuel pressure stay up during cranking? MAF muddy?

Any codes?

 

Thanks for the reply ishootstuff, I don't have the noid light to test fuel injectors so I cant say without any doubt the injectors are operating correctly. If a conclusion is drawn to lean in that direction than I will test them. Air filter is clean and fuel pressure rose slightly above 35 psi while cranking. A compression test has not been done. I cleaned the MAF and no codes have been set or I should say the check engine light is off but the battery had been disconnected since the problem started without codes if any were retrieved. You mentioned valve timing which brings up a question that I have had regarding spark at plugs. If the timing is off which I assume would be due to a malfunction with the timing chain would it still have spark at the plugs? Also how is valve timing checked? Is it still checked with timing marks on the harmonic balance?

 

I also don't have a commercial noid light set. I rigged something up with some LEDs I had laying around. Even more basic though, you can have someone crank the engine while you put your finger on the side of an injector and you should feel it clicking/tapping.

As far as valve timing, I think it's pretty unlikely, but if the valve timing were off enough for the engine to not start, a compression test would reveal that. Forgive my ignorance, but I don't know enough about the 4.2 to answer the question about checking valve timing, but I'm pretty positive it would not affect spark - but could possibly affect spark timing.

Again, not an expert on the 4.2, but the cam and crank sensors are typically hall effect and have reference voltage, ground and a signal wire. If you're getting 12v, that's the reference, you got ground too so that's good, but that last wire will generate a square wave signal in millivolts if it's good which is what you're really concerned with.

Youtube has a lot of vids on ways to test those sensors. If it were my truck, I would be leaning toward those sensors, but I don't know how the 4.2 uses them and if they would cause no spark, or no injector pulse or a combination of the two.

 

There was that guy who had a high mileage 4x2 on one of the islands. His had abnormally high compression and it turned out to be the pulley on the front of the crank has turned on the crank throwing the valve timing off. The keyway had worn causing the pulley to slip.
Probably not your problem. Just throwing it out there.