Replaced CPS, now truck wont start

[rocktamer]

Just like the title says. I put in a new CPS and the tried to start it. The truck crank but wouldnt start. I put the old one back in, but it still wont start. What could have broke by unplugging and installing a new sensor? Im at a loss...

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[ju015dd]

I would double and triple check the sensor. Maybe one of the wires has a bad spot on it.

[Joel]

It's rare, but not unheard of to have a bad sensor out of the box.

I agree to double check for a short in the wire.

[NoRalPh]

This is your '99?

If so, watch the tach as you crank it over on the starter. If you see the needle moving up slightly as the engine turns, it's a good indication the CPS is doing it's job and not your problem (you said you tried the original again - right?).

Coincidences do happen, the current problem could be unrelated or not the CPS itself but rather something got disturbed when you worked on it. If not the CPS, or the plug going to it, start with the basics....

WTS Light? - do you get it when you first roll-on the key?

Tach Movement? - does the tach needle move up slightly when cranking?

Fuel - pump runs? Fuel refilling filter housing? Tank below 1/4?

Is it cranking fast enough? - it won't even TRY to start if cranking too slowly.

Is your truck "chipped"? If so, remove it as a Test

[Joel]

Good call on cranking speed.
Batteries that are a little weak will spin the motor forever and never start it.
Throw a charger on it to rule that out.

[rocktamer]

It was a combination of cranking speed and being cold. I had the radio on as I was working, like I always do. It must have drained the batteries just enough. Put it on a trickle charge and it started up this morning. I'm thinking it might be time for new batteries. The radio on for a hour shouldn't drain it that much.

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[NoRalPh]

Here's a good video on the importance of Cranking Speed (especially on a '99)

7.3hard start cold no codes - YouTube

7.3hard start cold no codes - YouTube

All this becomes a more common issue now that it's cold. Charge the batteries back up Fully, then have them Load tested, Individually, at a High Rate (not those dinky 100A tester the Parts Stores use on 6cly gassers, you need @300A load to test ours).

[bakerc167]

Did you buy the sensor from ford or international? I had bought one from a local auto parts store an i couldnt keeping the truck running called international an got one put it in an truck runs fine.