99 F-150 4.6, Had no fuel pressure, replaced fuel pump w/ cheap Airtex. Started and ran perfect! The next morning no start. Let it sit for a few days until it got warmer outside. Truck cranked, coughed and fired. Suspected cheap pump but had pressure, replaced filter, Truck started fine. The next morning no start. Bought Delphi pump, had pressure with airtex, but replaced anyway. Truck cranked, coughed and fired. Ran great, drove home, shut off and restarted half a dozen times. Would not start this morning. Im thinking theres a cold temperature problem as it will start on warm afternoons and after its been in my shop for a while. This is my dads truck and I am unfamiliar with Fords. Any Ideas?
Sounds like you've ruled out the fuel problem. Have you tried pressing the gas pedal half way down (no further) during the no start?
Have pressed to the floor out of habit on flooded carbs. But not half way?
It cuts the fuel injectors off all the way down. Half way is a good way to test for a stuck IAC. Does the fuel pressure hold 35 after it cycles on or does it drain down quickly?
Just tried the half way, no luck. Fuel pressure is constant 35 and does not drain quickly.
Does it have spark?
At this moment im not sure, will check after work. Obviously had spark last night and am not sure why it could come and go with temperature or any other variable. My thought is you either have it or you don't. Maybe Im wrong?
crank shaft signal can come and go. Seems like it always give trouble on a cold engine. Check that for me during a no start and let me know.
I think my scanner here at work can look at crank signal, but am not sure. How late are you going to be on? I get off work at 2:30 central time and will be working on it afterwards. Will let you know what I find. Thanks
I ll be on here all day. Check the RPM signal during the no start.
The RPMs do not change on the scan tool while cranking. I don't know about spark yet as I ame here by myself and cannot be in two places at once. I realize I can jump across the solenoid but I don't have enough hands to make everything happen all at once. I will have help here soon so I will check spark then. Located the crank sensor and see that the compressor needs moved out of the way. ...... Just verified no spark.......Ok, went back outside and heated the area around the ckps with a heat gun, cranked for 10 sec and nothing. Kicked around for a few minuites, cranked again and it coughed, fired and went. Kinda pointing to the ckps. could be coincidence?
Yeah, I think it was just a coincidence. Try unplugging it and plugging it back in and see if it starts. I've had to replace the connectors on them before. I've also had to overlay the wires to the computer. Seems like it is always the wiring. It is possible the sensor could be bad also. I get my harnesses at the junk yard for over laying the wiring. All the f150 harnesses are pretty much the same. Might want to give them a call and see if they have a harness connector you can buy. Not sure if motorcraft offers a replacement connector. You can check on motorcraft.com.
If this helps you out please accept the answer. If you need any more help with this just ask.
Senior Master Ford Tech with 10 Years of Professional Ford Experience.
Thanks for the direction Tim! Turns out it was a faulty crank sensor. I pulled the old one out and it had a crack in the plastic housing down by the tip. Terminal ends looked good so I replaced sensor with BWD from Orielly's. Truck hasn't missed a beat since. Thanks again!