Hey all, first time here, and need a bit of advice. I am a concreteman, a good mechanic, and pretty fluent in gas and diesel engines as well as hydraulics...

Heres the gig. I recently purchased a 2001 f350 sd 5.4. Flatbed, and in very good condition, 150k miles, automatic. I took it upon myself to go thru the truck before handing to one of my employees, so i tightened things up here and there, as well as rerouted a few wires i thought may be in jeopardy. Next morning i went to my yard and hopped in to take off for work, and the engine turns, wont start...low on time, i fire up my international and work. Upon my return, i retry the ford and no fire...hmmm. i retrack my steps from.previous day, and cant find anything wrong. I weny thru relays and fuses etc. So i ordered a fuel pump and changed it out. Of course, it wasnt the pump. So next i decided to do a crank sensor, so i thought i would take a look at it, and of course i had unplugged it while cleaning up the wires i thought in jeopardy. So the truck starts right up and all is well....or is it...no. the next day i took the ford for a test run again, to.make sure i can hand this off to an employee. About 20 miles to the job, crappy l.a. traffic, 1 hour, all good. On my return, more l.a. traffic, traffic got moving, and suddenly the ford feels like its running out of gas, and i limp off the freeway. I make it to a gas station and fill tank to full, and truck feels ok again, for a few minutes anyway. Then while under moderate stress, the same "im running out of gas " feeling appears, but im close to my yard, and limp in... next up, fuel filter change, and it was a mud laden filter, yikes. I roar the truck around town, and im happy, for about 30 minutes anyway. With a mile to go to the yard, it does same thing, but only this time no stress, and on flat ground. Hmmm again. No codes. Check vacuum hoses, and have kind of a crappie one, one of the little guys on drivers side, mid way on intake manifold. Next day retest, and really put a load on, and took on freeway at high speed, and all the hills, awesome, full speed. Descend into town, catch a red light, and guess what, it does same thing again...now ses light appears...cool. so i stop by a ford truck place, seems super busy (6.0liter madness there), but a guy takes a minute to listen and grabs his code reader and dives right into my truck (cool), p00171, he says i have a vacuum leak, fix it and i will be fine. Limp to yard. Search high and low and cant find any leaks. Hmmm. How about a new maf sensor, and change exhaust manifold gaskets, bank 1 (had a small leak). I did a fuel pressure test, 32or so at idle, and goes up to about 40 when throttling up. No changes, and i would like to treat this employee to this nice truck, but not like this!

Any ideas comments and recommendations are appreciated. I do have an obd2 reader. If you need some concrete info, im fully skilled and will give you an answer if need info.

Thanks

 

Im surprised nobody jumped on this. Todays festival of fun...change air fter, and pressure regulator, if i can find such item. Will report

 

Welcome to FTE pumpoperator6. I have the 7.3 diesel and I'm a relative newbie to these SD trucks as well so I can't be of much help to you. Just giving you a bump here. Lots of super knowledgeable members on the boards ... hopefully one of them will jump in and offer their expertise. One suggestion ... next time try to be as descriptive as possible in your post title ... that's the bait that attracts the right fish if you catch my drift. Good luck with your issue!

 

Drift caught.

 

I'm still trying to digest what you wrote in your post...LOL. You seemed to have put the cart in front of the horse when you started working on the truck, by replacing parts before diagnosing.

Did you pull the filter again to make sure it's still clean? You said it was full of mud. Could the fuel tank be full of dirt?

Did you trace all your vacuum lines? Did you put a gauge on the system to check for leaks? the 171 code is lean on bank 1 so concentrate on that side of the engine first.

Causes of the P0171 code may include:

• A faulty fuel pressure regulator
• A weak fuel pump
• A clogged fuel filter
• A faulty powertrain control module
• A vacuum leak
• Faulty injector(s)
• Faulty oxygen sensor(s)
• A faulty mass air flow sensor

 

Yes, im a savage. Shoot first, check the codes later...im pretty laden with work, and i like the local shop, and im probably going to hand it off, so i can get.concrete on the ground. Im leaning toward pressure regulator as culprit

 

... funny. I think you'll quickly discover the prevailing wisdom on FTE is Ready, Aim then Shoot. In other words, get your truck working right by following the recommended diagnosis protocols and fix what needs fixing ... in stock form. Then, once it is running right, keep it right by following the recommended service and maintenance protocols. Mods and such come after if desired. Good Luck in chasing down this issue. Close the loop and let us know what you discovered.