etcetera Posted May 6, 2023 Report Share Posted May 6, 2023 This has been driving me insane for over a year. Ever since I got it. 2012 F550 shuttle bus. V10 6.8L with low 54K miles. Nobody can fix it. Had numerous mechanics look at it. One of them replaced the fuel pump. Same thing. It cranks and cranks ad infinitum and sometimes starts and lately not even that. If I use a starting fluid, it will "run" for a nanosecond, then cut out again. I thought it was the fuel pump for sure, didn't fix anything. I know I need to pull the fuel pressure. There is no fuel filter. It's built-in to the pump. I got a certified Ford guy with 20 years of experience look at it and declare it has bad gas. It has been sitting for 6 months since the last trip. It has maybe 5 gallons in it potentially bad and I added 10 fresh ones. No improvement. No start. The thing is, a year ago I completely circulated all the gas out of it and filled it with fresh gas and it still would not start. I think I am going to drop the tank again, maybe some gas disintegrated into residue (The PO from what I understand kept it parked for 2 years) and won't start for that reason even if you add fresh gas to it? It has a 50 gallon tank. If it does start, it will start OK for the rest of the day. That right there is a clue but I don't know what it means. Apparently the fuel pressure is good. Or is it? It runs really nice. Idles OK too. I need a mechanic with really strong diagnostic skills. I am completely frustrated with it. Quote Link to comment Share on other sites More sharing options...
Ranger Smith Posted May 6, 2023 Report Share Posted May 6, 2023 From another forum If you cranked it over a few times and it did not start , the plugs should be wet.Under the back of your truck should be a fuel pump driver module. Usually bolted to a frame cross member. They were known for corroding where mounted and resulted in starting problems with no fuel. See if you can find it take it down and if corroded where the back of it contacted the metal frame member , it will need to be replaced.If you are sure you are getting fuel under the right pressure then we need to look elsewhere as to why the injectors may not be working. Pulled the fuel pump control module but it’s an all plastic unit. Nothing looked corroded and wiring looked good but I replaced it and the truck fired up. No long crank anymore either. Thanks very much for your help! New part number through ford AU5Z-9D370-J. Quote Steve and Joy Amateur Radio Operator WZ1T . . . Flex 6600 M, Flex PGXL, Flex TGXL, 2014 Itasca Suncruiser 38Q . . . Lincoln MKX Toad The Kids . . . Yogi the Yorkie passed 10/20/2018. . . Cookie the Chihuahua passed 11/30/2017 . . . Cooper the Aussie Doodle passed 3/10/2020 Abbie and Abel the Doodles . . . Brother and Sister Born 02/02/2020 . . . Lucy the Yorkie . . . and Axel . . .The Bernie Doodle Where We Are Now Link to comment Share on other sites More sharing options...
RV_ Posted May 8, 2023 Report Share Posted May 8, 2023 (edited) 👍 Edited May 8, 2023 by RV_ Quote RV/Derekhttp://www.rvroadie.com Email on the bottom of my website page.Retired AF 1971-1998 When you see a worthy man, endeavor to emulate him. When you see an unworthy man, look inside yourself. - Confucius “Those who can make you believe absurdities, can make you commit atrocities.” ... Voltaire Link to comment Share on other sites More sharing options...
etcetera Posted May 15, 2023 Author Report Share Posted May 15, 2023 Forgot to say already replaced the fuel pump control module. And the fuel pump. I talked to a guy at an auto parts place, who seems familiar with the V10, he thinks it's the camshaft position sensor. Plausible? Quote Link to comment Share on other sites More sharing options...
etcetera Posted June 26, 2023 Author Report Share Posted June 26, 2023 The camshaft position sensor swap did nothing. But it was an easy swap. The crank position sensor swap was much more difficult, the mechanic had to remove the AC compressor but it finally started on the 1st try today, though it did crank for about 15 seconds, still too long. And I had to punch the gas pedal a bit, which makes no sense at all in an fuel-injected vehicle. But it works. Quote Link to comment Share on other sites More sharing options...
D&J Posted June 26, 2023 Report Share Posted June 26, 2023 7 hours ago, etcetera said: And I had to punch the gas pedal a bit, which makes no sense at all in an fuel-injected vehicle. But it works. Back when the Triton engines had a throttle cable they had a IAC valve (Idle Air Control) and when it went bad you had to step on the petal to get it to start but yours is drive by wire so I could be the throttle body or the TPS (throttle position sensor) not allowing air past to the butter fly when starting. Denny Quote Denny & Jami SKP#90175 Most Timing with Mac our Scottie, RIP Jasper our Westie 2013 F350 SC DRW 6.2 V8 4.30 Gears 2003 HH Premier 35FKTG Home Base Nebraska Link to comment Share on other sites More sharing options...
Wrknrvr Posted June 26, 2023 Report Share Posted June 26, 2023 This mite be old school thinking. Put a spark plug on one of the spark plug wires. Make sure it is grounded. Have someone turn it over and see if there is spark. Quote Link to comment Share on other sites More sharing options...
etcetera Posted June 27, 2023 Author Report Share Posted June 27, 2023 The mechanic said there is spark and there is gas. Today started after 8 seconds of cranking and some light throttle. That's right, some sensors have been deleted, it's all by wire. I will relay this to him: could be the throttle body or the TPS (throttle position sensor) not allowing air past to the butter fly when starting. Quote Link to comment Share on other sites More sharing options...
etcetera Posted July 9, 2023 Author Report Share Posted July 9, 2023 The crank position sensor is what fixed it, the plug had some oil on it and it caused the intermittent out of sync condition with the camshaft position sensor. Quote Link to comment Share on other sites More sharing options...
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