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05 LLY Fuel Limp with no codes, no CEL, tried everything i can think of

3K views 9 replies 4 participants last post by  ALLIS200 
#1 ·
Hello All,

the LLY project truck got put on hold and havent had a car for the last year so the farm truck LLY has been my daily through COVID.
Last weekend i was getting ready to take a trailer out to look at a car and it acted like i hit a false rev limiter at 2000rpm.
Shut down the truck after limping it home and tried to diagnose.

Symptoms:
Runs fine for 5-10 minutes then after pushing it hard it will hesitate and then max out at 2000rpm.
A little puff of smoke right before 2krpm
What sounds like injector rattle when i let off
Turbo sounds like it is pushing boost just fine, no odd sounds there.

What i have tried/already had done:
Turbo MP - ebay style
Fuel relief valve shim kit yesterday
Fuel filter yesterday
Double checked my EGR block off as it acted similar when the EGR went bad, but with more smoke
Checked all harnesses that i could. nothing seemed wrong there
Injector Ice pick was done right after i got the truck

The truck has never had a tune on it to the best of my knowledge. bought it at 130k miles and it is now at 184k.
again, i havent seen any codes or CEL during all of this, but i do only have a very generic scan tool.
Would you guys and gals have any ideas on what to look for?
 
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#2 ·
im having the same issues as you are with my lly,i have checked all of the stored codes.the only code i get is low fuel rail presure upon power enrichment.limp mode from low fuel rail presure.i have checked and replaced every thing on my fuel system except the fuel pump and injector pump.i did have an injector with problems and i heard that that problem can pop the presure releif valve.these things are junk.they are already the weak link in the fuel system.i will be trying my new presure relief tomorrow.
 
#3 ·
I ordered a filter head rebuild and a full plug for the fuel pressure relief just to be sure.

I’ll also be running it down to a local shop to check balance rates, fuel temp, and rail pressure.
I’ll post again when I get that info. Thanks all
 
#6 ·
Allis20 - when you are at the shop, have them check the MAF and MAP sensors for a reasonable reading, about 40 g/s +-5 at warm idle in park. MAP should be about the same as BARO, about atmospheric pressure for your altitude. These are critical for the ECM to deliver correct fuel to the engine.

Also, search for '2000rpm' (2000 rpm, etc and similar) as there are several other posts with similar symptoms
 
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#7 ·
Hey Ron! Thanks for the info! Just waiting on the plug and if that doesn’t fix it I’ll run it down to a shop where I borrow their solus scanner.
Mine won’t go any further than basic engine data. Yeah I dove through a bunch before posting and they all seemed to say fprv or cp3 so I started there.
Thought the fprv shimming would fix it but maybe I scratched the end cap when I installed it or something.
Thanks again for the info I’ll add on after Wednesday!
 
#8 ·
Check fuel lines next to fire wall on drivers side. They collapse
 
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#10 ·
Hey all,

FIXED THE ISSUE
hate to bring a dead thread back from the grave but the problem came back after the above repairs, wound up swapping all supply braided hoses to parker 801 hose and it didn’t help, went through the whole system and even pressurized the tank to try and find a leak.
wound up tearing the intake and egr off the old lly to see what was going on and found the 5/16” cp3 supply hose absolutely demolished. Flat as can be and barely hanging on at each end, no clue how the truck even ran as is.
Just thought id add this to maybe help anyone in the future as I had no idea there was any soft lines on the top of the motor.

symptoms:
Rail pressure dropping from 24k psi to about 400 at 2400rpm
Rail pressure would spike immediately when the throttle was let off
No codes other than an 093
Truck ran fine cold
Hauling an empty trailer up a hill was absolutely impossible

thank you all on the forums for the unlimited help!
 
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