2002 King Ranch 5.4 is very hard to start. Sometimes it takes several minutes. It usually does better if I leave the key on for a while. Almost like it has to charge or warm up or something. I have replaced fuel pump and filter and crankshaft sensor. Same problem. I have good pressure to the rails and it does not bleed off. We put NOID lights on coil and injector and when it won't start, there's no pulse. When it does randomly fire up, it runs great. No miss and no sputter. And NO Codes. I am thinking I need to replace PCM, as I think it receives signal from crankshaft sensor and sends to coils and injectors. Anyone dealt with this? Please help! Thanks!

 

There are a number of things that *might* be going on. You need to narrow down the possibilities.

Next time it fails, check to see if you have switched battery power present at your COPs and injectors. If it is missing, the noid will fail just as if the pulse is missing.

Verify that the odometer displays correctly and that PATS proves out during power-up.

Observe the tach while cranking to see if it shows activity or not. If not, the PCM may not be seeing a crank sensor signal.

 

Thank you for the reply! Yes, we have power present whether it starts or not. Any other thoughts?

Oh and the theft light is not fast blinking, and it does it with both keys, so I think we have ruled out PATS. Thanks again!

 

And the tach does not show activity while cranking. Only when it fires.

 

Check the crank sensor.

 

replaced it already

 

Simply replacing it is not the same as diagnosing. Did you check to see if it is putting out a signal and that the signal is making it to the PCM's input?

 

Thanks again so much for your help. I have a retired Ford mechanic helping me when he has time. I’m not sure if he checked to ensure the new sensor was sending a signal to the PCM. I assume he did, but I better not assume. He can’t help me this week. What is the best way to see if the PCM is receiving the crankshaft signal?

 

A scan tool with PID capability is what will tell you if the processor is seeing the CKP signal
I see no reference to codes or pinpoint teats for a no start diagnosis
I would start with a code test.
Anytime it will not fire there should be a code set

 

Thanks for the reply. No codes. I wish I had one.