4.2 hard start

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Old 10-10-2011, 07:23 AM
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4.2 hard start

2001 F150 4.2L V6 with approx 108k miles has a starting issue. Here's what i know. Has been starting hard for over a year, now its time to sell and i need to fix the issue. Always fires right up first thing in the morning after its been sitting 10-12+ hours. Runs and idles as smooth as new. Once it reaches operating temp and is turned off, it will restart just fine within about a 10 minute window. Any amount of time over about 10 minutes, it will turn over for 5 to 10 seconds before finally starting (it will start every time) and sputters and coughs as it has flooded itself and then everything smooths out and all is well. Been to the dealer 2x and they don't know whats wrong, but figure they can fix it for about $1400. What I have done, new fuel pump and filter. New air idle control valve, new cam position sensor, new throttle position sensor, new evap canister purge valve (sounded like a vac leak was occuring), injectors cleaned and tested, checked the relays all seems fine, have spark as soon as the key is turned, fuel pressure always at schraeder valve always in spec (regulated or unregulated values both). Can't remember what else off the top of my head.... Problem has been occuring for over a year, and seems to be temp related (not sure how long it takes for the entire engine block to cool, but im guessing something over 9 hours as it turns over for a long time after its been sitting parked while im at work). I'm at the end of my rope... possibly something opens or closes as the engine heats and won't re-close or re-open until everything is completely cooled... ANY help or suggestions (other than scrap it) would really be appreciated.
Thanks
Jeff
 
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Old 11-07-2011, 10:45 AM
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Let me know if you've made any progress with this issue. I think I have the same thing going on.

It will take 5-10 times of starting it to actually catch and start running. Once it's running it runs flawlessly and drives well. It seems engine temp or time related. If I drive it for a while, shut it down, I can restart it immediately without issue. Waiting 2 hours and it stumbles a little but starts fine. 10+ hours, overnight and it's always the same hard start issue.

I'm about to do Fuel Pressure Regulator, Fuel Filter and Fuel Pump hoping one of those is the culprit.
 
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Old 11-07-2011, 03:02 PM
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sounds like youre losing pressure. easy way to check is to turn the key on in the morning, not far enough to turn the engine over, and let the fuel pump turn on and pressurize the system. turn the key off after 3 to 5 seconds. then turn the key to start the truck, if it starts right up, you're likely losing pressure somewhere and the fuel pump is simply refilling the system after the presure has dropped. or get a pressure gage and check the fuel pressure at the rail (there's a schraeder valve) should have pressure at all times, even after sitting awhile. if you leave the gage on and check back periodically and the pressure is dropping, there's a leak somewhere. if there is, the regulator and pump would be good place to start. you may also be losing pressure somewhere in the line, leaking injectors, and on and on and on although you'd probably smell it if the lines are leaking.
im having the opposite problem. if mine sits overnite it fires up right away, if it gets up to operating temp it doesnt want to start until its cooled back down overnight. Im not losing pressure, at this point i think i might be losing my mind
good luck
 
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Old 11-07-2011, 03:25 PM
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Thanks for the response. I should have mentioned what I've tried. I did the key on key off process as many as 15 times. It has no effect on the cold startup at all. I just did the fuel pressure regulator just now so I have to wait to see if that makes it any better. I was physically unable to remove the fuel filter yet somebody wrote Nov '10th on it. Although not impossible, it seems unlikely it got this bad in 12 months. Next step will be testing the pressure as you mentioned and a new pump.
 
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Old 11-19-2011, 07:00 PM
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Fixed it

I'm not sure if this will help you, but I want to get this solution out there. My issue turned out to be the Cylinder Head Temperature Sensor (CHT). Although I only got the error code P1289 once after many times of clearing the codes and driving more, that's the one that eventually lead me to this sensor. I learned through plenty of troubleshooting and searching that the dash cluster temp gauge gets it's signal from the coolant temp sensor on the thermostat housing. The computer gets it's signal from the CHT. My CHT was malfunctioning and was causing the engine to never start properly. It would take 10+ times to start it properly. The CHT sensor itself is a dealer only part. It was $23 dollars from a local Ford Dealer, in stock. When I got back to replace it, I snapped the old one off inside the head. No biggie, because there are about 3+ other tapped holes in the head to screw the new one into. I used a different hole and the engine started on the first shot. This was a really easy job because this was a E150 van and I have direct access to the back of the engine. I imagine it would be sort of a headache on a F150. I hope this helps somebody. I will repost with more details elsewhere so forgive the multiple posts, just trying to help others.
 
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Old 06-07-2014, 08:41 AM
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2001 4.2 hard start - finally solved!

My 2001 f150 xl 4.2l With 125k miles will also crank but not start. No codes but thanks to forum members advice, I hooked up a scanner and it showed no rpm while cranking. The fuel pressure is 35 psi. I pulled a plug and grounded it, but no spark. Prior to it not starting at all, it would start using starting fluid but even that took more and more fluid over time. Eventually, it started to stall at red lights, then one day it wouldnt start at all. Before it totally crapped out, i replaced the CHT but apparently that wasnt the problem.

I located the Crank Position Sensor (CPS) on the lower front right side of the engine (as viewed by driver) just above and behind the harmonic balancer, which is the heavy pulley at the lower front of the engine that drives the serpentine belt. The CPS is fully external to the engine and is held on by 2 8mm bolts. I replaced it for $20 and now it starts and runs just fine.
 
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Old 09-23-2018, 02:15 PM
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Originally Posted by jw1028
2001 F150 4.2L V6 with approx 108k miles has a starting issue. Here's what i know. Has been starting hard for over a year, now its time to sell and i need to fix the issue. Always fires right up first thing in the morning after its been sitting 10-12+ hours. Runs and idles as smooth as new. Once it reaches operating temp and is turned off, it will restart just fine within about a 10 minute window. Any amount of time over about 10 minutes, it will turn over for 5 to 10 seconds before finally starting (it will start every time) and sputters and coughs as it has flooded itself and then everything smooths out and all is well. Been to the dealer 2x and they don't know whats wrong, but figure they can fix it for about $1400. What I have done, new fuel pump and filter. New air idle control valve, new cam position sensor, new throttle position sensor, new evap canister purge valve (sounded like a vac leak was occuring), injectors cleaned and tested, checked the relays all seems fine, have spark as soon as the key is turned, fuel pressure always at schraeder valve always in spec (regulated or unregulated values both). Can't remember what else off the top of my head.... Problem has been occuring for over a year, and seems to be temp related (not sure how long it takes for the entire engine block to cool, but im guessing something over 9 hours as it turns over for a long time after its been sitting parked while im at work). I'm at the end of my rope... possibly something opens or closes as the engine heats and won't re-close or re-open until everything is completely cooled... ANY help or suggestions (other than scrap it) would really be appreciated.
Thanks
Jeff
I have the same problem as you do. I have a 2003 F150 with a 4.2 motor. I tested the fule presure at the rail and as soon as I turned the truck off, it droped like a rock. IM a mechanic and work on diesel trucks. So IM not brain dead. I got an idiot light on the dash from trying to start my truck when it was warm. I cleared the code and now when I start the truck when its hot, after setting a few minuets like your truck, I crank it about 1 seckond and stop. Then crank it again and it starts right up. No code will come up then. IM pretty sure its fule at this point. Leaking fuel injectors or fuel pump check valve act. Hope this helped you.
 
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Old 02-14-2020, 07:58 PM
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I have given up on the dealer. Or at least two so far. Couldn't replicate problems or say it's out of normal. Not the sharpest techs and just poor quality service. I guess you get what you pay from with warranty service. I'd be content with getting parts and doing the work myself or having a trusted mechanic do the work.
 
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