So I'm just finishing up replacing a blown 4.6l and upon trying to start it, ran into a no start issue. Double checked the ground to the chasis, ground on back of engine. My next thought was crank sensor, but since I haven't finished buttoning up the exhaust yet, I was able to see the manifold did drip a little fuel after trying to start it. So it's clearly signaling the pcm to pulse the injectors, which would in my opinion rule out the crank sensor. Also worth noting it does not have a flashing security light so its not the security system(2002 f150) disabling anything to my knowledge. Any suggestions as to which way to go? I'll test the coil in the morning but am almost certain they aren't firing. I'll also run a compression test since it is a replacement motor but compression sounded good when cranking. I'm just wondering if there's anything else on the eletrical end be it wiring or module thats throwing it off?

 

Nope. The crank sensor doesn't signal the PCM to do that, the crank sensor signals the PCM to fire the coils. It's the cam sensors that are used to synchronize the injectors.

Observe your check engine light while cranking. If it goes out, the PCM is receiving a crank signal. It it stays on, then it isn't.

 

So I just went out and did a little more diagnostics. The check engine light goes out when I turn it over and stays out while cranking. Which from what you're saying would indicate the crank sensor sending a signal to the pcm. Could it be faulty and just not sending the correct signal or is it more of a either it does or doesn't type thing? I double checked the coil connectors and they are recieiving voltage with the key on.

 

You need to see if the cops are actually firing, you can use an inline spark tester for that.

 

will do, have been holding off since nobidy else is around to crank the truck fir me to check til later this afternoon. So have just been knocking out what I can by myself til then. So lets say it comes up with no spark on the coils what direction should I look then? And assuming they do, I'll run a compression test but that would basically rule out to timing wouldn't it?

 

So I tested spark, no spark. Pulled the cranksensor at that point to find it was covered in ground down metal paste. So I'm starting to suspect the motor itself might not be the greatest.