Another head scratcher.
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Postmaster
Joined: Oct 2005
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From: Northeast TN
Another head scratcher.
A buddy of mine has an '02 F250, CC, 6sp, 4X4, all stock except for a 6637 and a superchips programmer. He called me today and said that his truck loses power over 2000 RPMs. I went over with my AE and did a buzz test, data loged the ICP psi and DC. I tried to do a cylinder contribution test, but couldn't get it to work. Anyway, we did several wot runs and could not get to 70mph. I couldn't feel any shutter or shaking, it would just quit pulling. We removed the superchips tune and the truck made one good wot run and on the next run it lost power again. His ICP was over 2600 at 52% DC, oil is clean and full, fuel filter is 3 months old and we get a strong stream of fuel out of the fuel bowl. I'm thinking it's a fuel problem but I may be way off base. We are going to install a fuel pressure gauge this weekend. What pressures should we see at the gauge? Could this be a weak fuel pump or a clogged screen in the tank?
Thanks for all the help.
Thanks for all the help.
Post Fiend
Joined: Mar 2007
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From: Texas
The key to fuel pressure is not the number, but the drop at WOT. We have an electric pump, so it's either on or it's off. If low volume causes a pressure drop under load, the screens inside the mixing chamber in the tank would be my first guess.
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Postmaster
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From: Northeast TN
That's what we were thinking. We're gonna run enough hose to temporarily mount the gauge on the cowl.
Post Fiend
Joined: Feb 2006
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From: Middle Tennessee
So if it is only during pedal mashing that it flounders then check the fuel supply. If you creep up to 2k and cannot go further, then still check the fuel but begin to think of other things and definitely do some good data logging. I won't insult you with the boost leak thing that I am sure you checked. BTW, what kind of boost is it making before it falls on its' face?
Of the next Riffraff East
Joined: Oct 2004
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From: Concord NC
Huck, how long has he owned the truck? Did it used to do better? Just wondering if it is new to him and maybe the PO had a speed limiter or govener installed? Just thinking on the keyboard outloud.
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From: Northeast TN
Well put Chris and very true. Some thoughts that come to mind in this instance is the part where the truck falls on its' face over 2k rpms. I would think that one would be able to cruise on the highway up to and beyond 2k rpms which is not WOT but this is not covered in the post.
So if it is only during pedal mashing that it flounders then check the fuel supply. If you creep up to 2k and cannot go further, then still check the fuel but begin to think of other things and definitely do some good data logging. I won't insult you with the boost leak thing that I am sure you checked. BTW, what kind of boost is it making before it falls on its' face?
So if it is only during pedal mashing that it flounders then check the fuel supply. If you creep up to 2k and cannot go further, then still check the fuel but begin to think of other things and definitely do some good data logging. I won't insult you with the boost leak thing that I am sure you checked. BTW, what kind of boost is it making before it falls on its' face?
He has had the truck just over a year. It has done a lot better in the past. He didn't even notice this until this week. He was hauling his tractor to another hay field and noticed it then.
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Post Fiend
Joined: Feb 2006
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From: Middle Tennessee
15 PSI is more than enough to accelerate from 2K RPMs on the highway/interstate. It is not ideal but heck I cannot remember what mine made stock. I will say I can roll into it at 2K RPMs with a lot less than 15PSI and accelerate away.
It takes fuel to make boost, with other things. I cannot remember what mine made stock when I hammered it. Anyone?
Edit: somehow ~19PSI comes to mind.
It takes fuel to make boost, with other things. I cannot remember what mine made stock when I hammered it. Anyone?
Edit: somehow ~19PSI comes to mind.
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Duct Tape Tech.
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From: San Antonio Tx.
What kind of power do you see if you go wot in 1st or 2nd gear will it go past the 2000rpm mark and still make power or do you see the same thing there. I guess Im asking if it is a speed or rpm kind of thing.
Posting Guru
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From: Buckingham, IA
What is his exhaust system like? Does he have a muffler or cat? My f-i-l had a gasser that would idle and cruise around town ok but wouldn't get up to speed on the highway. There was a screen over the tailpipe outlet that was covered with rust. Removed the screen, started the engine and blew out the rust and was good to go. This would definitely be related to engine speed. Can he rev the engine past 2k and hold it while in park?
Hotshot
Joined: Jan 2008
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From: Rochdale MA
A buddy of mine has an '02 F250, CC, 6sp, 4X4, all stock except for a 6637 and a superchips programmer. He called me today and said that his truck loses power over 2000 RPMs. I went over with my AE and did a buzz test, data loged the ICP psi and DC. I tried to do a cylinder contribution test, but couldn't get it to work. Anyway, we did several wot runs and could not get to 70mph. I couldn't feel any shutter or shaking, it would just quit pulling. We removed the superchips tune and the truck made one good wot run and on the next run it lost power again. His ICP was over 2600 at 52% DC, oil is clean and full, fuel filter is 3 months old and we get a strong stream of fuel out of the fuel bowl. I'm thinking it's a fuel problem but I may be way off base. We are going to install a fuel pressure gauge this weekend. What pressures should we see at the gauge? Could this be a weak fuel pump or a clogged screen in the tank?
Thanks for all the help.
Thanks for all the help.
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Joined: Feb 2008
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From: Central Washington State
Some on here may recall, last Fall I was on a hunting trip to Idaho riding with a friend when his truck started losing power and, in fact, got to the point that it would not go over 15 mph. The problem turned out to be a disconnedted EBPV that was rusted and had somehow worked it's way closed. I know it sounds strange, but I watched a mechanic at the dealership in (I think) Post Falls work on it. (good guys by the way) Jus t another thought.
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Postmaster
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From: Northeast TN
What is his exhaust system like? Does he have a muffler or cat? My f-i-l had a gasser that would idle and cruise around town ok but wouldn't get up to speed on the highway. There was a screen over the tailpipe outlet that was covered with rust. Removed the screen, started the engine and blew out the rust and was good to go. This would definitely be related to engine speed. Can he rev the engine past 2k and hold it while in park?
Some on here may recall, last Fall I was on a hunting trip to Idaho riding with a friend when his truck started losing power and, in fact, got to the point that it would not go over 15 mph. The problem turned out to be a disconnedted EBPV that was rusted and had somehow worked it's way closed. I know it sounds strange, but I watched a mechanic at the dealership in (I think) Post Falls work on it. (good guys by the way) Jus t another thought.
Thanks for all the replies! Keep 'em coming. If I can't work on this tonight, I will tomorrow.