LMM falls flat on its face, puzzled

z79outlaw

Member
Apr 20, 2007
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Salem WI
Now Im honestly not sure how long its been doing this, I honestly cant remember it happening during my 5,000 mile quest to get a mule deer with my bow, which I came home empty handed, but over the course of the last month it seems to be happening with come frequency, it happens in these 3 scenarios.

#1 Cruiseing 55-75 if I try to give it throttle it'll fall on its face puff a cloud of white smoke and go. For what seems like a solid second this happens.

#2 I'll be driving casually keeping revs under 2000 accelerating to highway speeds and around 55 - 65 it'll do the exact same thing.

Now these 2 things I thought maybe was a issue due to 6th gear and having tires that measure exactly 34" in diameter but I have this issue below which puzzles me as well

#3 I'll be rolling through an intersection or stop sign, and when I go to take off say rather quickly to shoot a gap or beat traffic, at least 3 times now the truck has completely fell on its face and I had nothing for at least a second again. this is rolling at about 5 mph once and somewhere around 15-20 twice.

After that my thought was maybe I had my vein posistions to low and was causing the motor to snub out when I needed it to go again suddenly long shot and it didnt work. Had a slightly modded tune in with DPF delete, tinkered with it somemore mainly just the vein posistions to no avail, and now I'm running the stock programming with DPF delete and still have these problems. I changed the fuel filter a few weeks back after a few weeks of intial troubles but see no change yet. No codes thrown, hard or soft and the injector balance rates look good, though im not sure I ever read a spec for the LMM injectors to be in. Im about to park the truck for the winter, before the roads get salted. But I'd like to get this out of the back of my mind, so I can concentrate on whitetails the rest of the year. I've done some searching but really dont see this mentioned anywhere and not really sure what I should search. It doesnt happen often enough that I can log it and to randomly as well, but maybe 3 - 5 times on a 2-3 hour trip, and more so after its been running for awhile.
 

dmaxfireman

'Can do' kind of guy
Apr 8, 2007
2,329
1
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CT
who tuned it and did this start when you put a new tune in it?

did you make sure you bled all the air out of the filter? sounds to me like you have air in the system.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,761
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Phoenix Az
I had that issue with a pretty dirty fuel filter but you supposedly marked that off :confused:

x2. is the filter tight along with the WIF sensor? do you have a lift pump? mine jsut did the same thing you are describing suddenly last week but it kept spewing white smoke till i shut it off and restarted. Pretty sure my fuel filters are dirty as it did this before a year ago when i went too long on a filter change and had been runnin some BG stuff that apparently cleaned the crap out of the tank (didnt know that at the time, glad i had two fuel filters on)
 

z79outlaw

Member
Apr 20, 2007
793
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Salem WI
who tuned it and did this start when you put a new tune in it?

did you make sure you bled all the air out of the filter? sounds to me like you have air in the system.

I'll double check everything tommorow, look for leaks and see if I can squeeze any air out. I tuned it myself, but it wasnt anything complex, just a little pulse width, a touch of timing and the DPF and EGR disabled. I dont remember having issues in may when I got rid of the DPF, but I've never drove my truck much either.

x2. is the filter tight along with the WIF sensor? do you have a lift pump? mine jsut did the same thing you are describing suddenly last week but it kept spewing white smoke till i shut it off and restarted. Pretty sure my fuel filters are dirty as it did this before a year ago when i went too long on a filter change and had been runnin some BG stuff that apparently cleaned the crap out of the tank (didnt know that at the time, glad i had two fuel filters on)

No lift lump, but then again I'm not commanding much fuel, it runs great at WOT without a hiccup it doesnt like when I baby it. Hopefully I can figure this out, and what should be one of the last trips for the season goes smooth.
 

Dalyfarms

New member
Jan 12, 2010
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Centrailia Mo
I know on my truck, when changing the fuel filter after pumping it up and closing the bleeder, I have to pump it up again to reset the filter life. I have not seen this adressed in here before, and heck it might say to do that in the owners manual, but I use the instructions as a last resort ha ha .
 

Jesseh72

Member
Nov 12, 2012
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6
Avon Ohio
I know this is an old thread but did you ever find the issue? I am having the same problem with my LMM I am thinking it is tuning but not positive. I bought the truck 4k miles ago all stock. Shimmed the fprv, ported the fuel fitting, s&b intake, efi live, dpf delete & air dog 2. I did not notice the truck when stock. I put a new filter on the truck, cleaned maf sensor. I did not drive the truck much this winter so I am unsure when the problem occurred
 

gmac32

Member
Dec 8, 2009
288
3
18
bellville ohio
The stock fuel supply line can almost collapse in half under the drivers door. It makes a 90 bend there and the one I replaced was pinched in half and starving for fuel and that was with a airdog on it
 

z79outlaw

Member
Apr 20, 2007
793
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Salem WI
It was a tuning issue, Josh helped me out with it, I'm pretty sure the throttle blade for lack of a better term was flucuating.
 

messejme

Jazzy, Me and Max
Mar 7, 2008
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Branchburg NJ
I have the problem also when I run at RPM's above 2500 for a decent length of time. What do you guys use for replacement fuel lines?
 

dirty_max

Member
Jan 27, 2013
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eureka il
The stock fuel supply line can almost collapse in half under the drivers door. It makes a 90 bend there and the one I replaced was pinched in half and starving for fuel and that was with a airdog on it

how can you have a line collapse when it has pressure in it?
 

slipclutchms

Member
May 24, 2010
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What table controls the "throttle blade" and what exactly did you change in your original tune to create the problem and then correct it? I am not looking at my computer right now and I am curious :)
 

gmac32

Member
Dec 8, 2009
288
3
18
bellville ohio
it is like right at the 90 bend it degrades. When it is warm or when you just get done running your truck, pinch the hose at the 90 and see if it is collapsed or real close to it. In regards to the other post, you can still have pressure and not enough volume.
 

Jesseh72

Member
Nov 12, 2012
32
0
6
Avon Ohio
It was a tuning issue, Josh helped me out with it, I'm pretty sure the throttle blade for lack of a better term was flucuating.

Thanks for the heads up I am still having the issue ran some logs with my tuner and they showed nothing (could not make the issue occur of course) I will mention what you just said when I take it to him in spring. I must have missed your response prior to this.