2008 F150 XLT 5.4l 3valve ISSUES NEED HELP!?

As mentioned above i have a 2008 F150 XLT 5.4L 3VALVE truck that has an issue. So weeks ago i left work and drove about 5 miles to a store and parked it. When returning to the truck it would crank over like normal but not start. After about 20 mins it decided to fire and i drove it home which is about 3 miles from the store. It did this again the next day so i parked it for a while til i had time to dive in. During this little no start issue the fuel pump comes on and the check engine light was not on AT FIRST. Now i began diagnosis and outta no where the CEL is on so i hooked my scan tool and got a P061B code so i just decided to replace some things that really needed done anyways. Cleaned throttle body, cleaned MAF sensor, new battery, good grounds, new fuel pump driver module, new air filter ( these all are things that have been done recently that i had and never got time to do untill now ). So after the new installs it fired right up and i test drove it and it ran amazing! Parked it for a day and went to start it today but once again cranks and wont start. So i began inspecting wiring, fuses, relays etc. When turning key to the on position the CEL is there but my scanner shows no codes. My question is considering the RPM guage wont move while cranking could this mean the Crankshaft Positioning Sensor is shot? and would this have been my initial random issue to begin with and it just finally went? Last thing i can tell you is upon inspecting the sensor i see that some oil (i think) has been shot on the sensor and plug would this cause it to go bad this fast? Please give insights i know it seems simple but i want to find this issue AND find what caused it instead of just throwing parts at it untill it runs. Thanks!!

I can offer some quick checks to do before doing other pinpoint tests.

I see that the CEL comes on with the key, and that's great. Does the CEL stay on during cranking? Or does it go out?

Does your scanner just read codes, or can it watch live data as well? If so, look for the fuel rail pressure PID. I saw that you replaced the FPDM, but that doesn't mean you have fuel pressure.

Does the same scan data show the engine RPM changing during cranking?

Thank you for helping me out i appreciate it. So i do believe the CEL goes out during cranking but ill have to go double check that to be sure. As far as the scan tool i have its going to be a joke to most of you guys lol but i sold my old tool years ago and decided i needed a cheap quick " carry on me " tool for personal use only. So i purchased a Zurich ZR13 a few years back. Surprisingly it is better than expected but yes it does read live data and with KOEO fuel pressure is in the 30s but during cranking it shoots up to the mid to high 60s is this a decent pressure? And last night i ran live data while cranking and i am almost positive the scan tool was reading like 780 +or- RPMs. In the past iv done multiple repairs on this truck like manifolds and full exhaust, plugs and coils, 02sensors, power steering pump and lines, rack and pinion, cam sensors, vct solenoids and more so im hoping i can figure this out and continue running this thing for a bit longer without to much headache lol thanks again

I think you found your problem fuel pressure koeo should go 50-60psi initially then drop to what your fuel pressure regulator is set for. Now you just need to isolate why its that low or if it drops fuel pressure and how much over a ten minute period.

Ok thanks for the tips just a few questions. I see you said it should go to " 50 to 60 psi then drop to fuel regulators set point" . I do believe this is what its doing it goes up to the 60s then drops down to 30psi. I noticed tonight that theres oil all over the crank shaft sensor area and unfortunately it looks to also be blown all over the oil pan seems to be coming from the front main seal possibly? But im thinking the crank sensor COULD POSSIBLY be bad but its not showing me the crank sensor code when scanning the truck? I dont know this trucks honestly pretty rough in the engine compartment as far as dirt dust and grime from previous owner but still is my fault i should have took the time to properly clean everything in the first place lol. thank you guys again and anymore replys would greatly be appreciated! I also wanted to know does a bad crank sensor ALWAYS throw the code or is there situations that the sensors bad and no code??

It just depends on what your regulator is set for. most are set to ~42 psi. I would say to double check that with what is stamped on the regulator.

As for the chance of crank sensor acting up with out a code it is possible this is where a ocillascope comes in handy.

To throughly check crank sensor you will need a ocillascope. But if you have a digital multimeter there is some basic checks you can do. Check for ref voltage and ground. Also check cam sensors ref and ground and since the cam spins slower you can check signal wire for low and high signal pulses. However a ocillascope will work best for this.

DKEMP80 wrote: Surprisingly it is better than expected but yes it does read live data and with KOEO fuel pressure is in the 30s but during cranking it shoots up to the mid to high 60s is this a decent pressure?

That typical behavior of a FPDM system, in my experience. They'll run the pump harder during cranking and WOT conditions, then back them off during idle and cruise. Watch this PID during a test drive to get a better feel for it.

Now all you have to do is watch that PID during the no start.

So i do believe the CEL goes out during cranking but ill have to go double check that to be sure.

This is an important test. On Ford products, the CEL going out during cranking indicates that the PCM received a valid RPM signal, of which the crank sensor is a big part. The CEL staying on during the no start would point towards a crank sensor/cam sensor/input problem. The CEL going out would point you away from the same.