I have a 2001 F150 4.6L V8, It will crank but not start. I sprayed starter fluid in the air cleaner but no change, I checked the Cam Position Sensor & it changes OHMS when I pass metal past it, I checked for voltage at the sensor plug (with the key ON) & I see no voltage coming from the PCM??? Is there something else that cloud cause it to not get voltage or to not start?

Thanks

 

Dunno about the Cam Position Sensor. Do you have spark? Do you have fuel pressure? Are the fuel injectors firing? Is your theft light on the dash flashing by any chance? What made you go straight to the Cam Sensor?

- Erik

 

If the crank trigger is bad it will crank but not inject fuel.

 

Your not getting fire or the starting fluid would have made it hit. Check all your fuses. Did it just happen? What's the trucks history

 

I have not checked the fuel pressure, I checked all the fuses inside the cab & in the power distribution box, I checked & tested all the relays they are all good. (I switched them all 1 at a time with the power window relay & they all worked) I figure it has to be a spark problem because I sprayed it with starter fluid & it did not try to run. It just cranks. The truck was running fine the day before, has 130K miles & this is the first time of any problem. The motor has Coil over plugs, so it doesn't have a distributer, & the CPS is what fires the sequence. I have a manual & it looks like the power to the sensor comes from the PCM (NO power at the plug), but I don't want to spend $250 to try a new PCM. The day this happened it was -5 deg. outside & I can't get it in a garage.

 

Unplug both radio noise capacitors and see if it starts.

.

 

Where are the radio noise capacitors? Why would that have an effect?

 

When you turn the key from off to run ( do not start ), does the theft light in the cluster go out ?
Also at the same time, listen for the fuel pump to run ( as long as it is not past 4 seconds, auto shut down )

Did you check the inertia switch ?

 

I checked the inertia switch & it was ok, I'll have to watch the theft light when I get home & try it again. When I turn the key I hear a click I'll have to listen for the fuel pump.

 

Check the HDR ( crank sensor as 01Roush suggested) It is located between the a/c compressor and the engine front cover at the bottom front passenger side of the engine. Make sure the wire lead for the HDR did not make contact with the a/c pully and get damaged also make sure the connection is not loose. If this sensor is faulty the engine will not start.

 

Tonight when I got home I put the cam sensor back in, made sure it was connected good & the truck started right up like nothing was wrong! I let it run for 15 minutes, turned it off & IT WOULD NOT START!!! Does that mean the cam sensor is bad?

 

Stranger things have happened lol, yea that's usually the Crank Sensor. Did you check that out ? Also, don't crank her more than 4 seconds continuously, the PCM shuts down the injectors. I would say if you have no fire, -it's the Crank or PAT's.

Do you have a CEL now?

 

Did you try that ? Their right on top of the manifold. Personally, I didn't know they interfered with the ignition, but it's easy enough to try.

What can interfere with the ignition is the harness itself, when resting on the AC accumulator. The Mag field can disrupt your ignition, although,- not to a point of Crank no Start IMO. It can make them miss.

 

That is typical of a cam sensor. The vehicle will still start approx 50% of the time when a cam sensor goes bad.

 

There you go - I learned something anyway - For some reason, I don't know much about that sensor lol.

I've tried to pull mine once, but the damn thing didn't want to be removed, - it's in their pretty tight! Sense I didn't know squat and it's been in there since day one, I let it be