alright i'm sure this has already been addressed on the forum before but i cant find it...i have a 05 lly with only a 4 in exhaust ,NO TUNER, and while towing 8000 lbs my truck goes into limp mode!..my trans temp is right at 200 and my engine is running cool..can someone give me an answer to what the hell is happening? i always hear about the lly's overheating but nothing is overheating on my truck!!!and it still goes into limp mode

alright i'm sure this has already been addressed on the forum before but i cant find it...i have a 05 lly with only a 4 in exhaust ,NO TUNER, and while towing 8000 lbs my truck goes into limp mode!..my trans temp is right at 200 and my engine is running cool..can someone give me an answer to what the hell is happening? i always hear about the lly's overheating but nothing is overheating on my truck!!!and it still goes into limp mode

If it is going into limp mode but NOT getting the check engine light, then odds are strong it is a 1093 code, which means you have a weak spring in your fuel pressure regulator valve (FPRV).

You can try a new fuel filter, but if that does not solve it then its time to shim the FPRV. :)

10-4..yeh just replaced fuel filter about 4k miles ago.. never limped before that now since i'm thinkin about it...not sure if its just a coinendence

10-4..yeh just replaced fuel filter about 4k miles ago.. never limped before that now since i'm thinkin about it...not sure if its just a coinendence

Take this into account though, you will automatically see more 1093 action in the summertime because fuel temp gets very high and tends to aerate the fuel. So four months ago you were less likely to get a 1093 as you are now in the summer. :)

If you have a scanner check out fuel temp sometime it will blow your mind how hot the fuel is getting. ;)

I replaced the fprv 6 months ago havent had the code since... that where i would be looking..

My P1093's always set the CEL. Must be a CA emissions thing.

I have a 05 CK3500 dually crew cab 33,k. I have had the limp mode problem forever, when pulling a heavy load. I am usually pulling either a 25ft 5th wheel flatbed with 15000lbs of hay or a 35ft 5th wheel RV 9500 dry weight estimate 14,000 loaded. My dealer first replaced the fprv. Still had the problem, then they replaced the fuel pressure sensor in the center of the fuel rail, and the valve ? on the other end. Still had the problem. Just recently took it to another dealer and the replaced the injector pump. Haven't pulled anything yet, so don't know if it worked or not. The dealer said that GM had extended the warranty on the pumps to 200,000 miles so apparently I'm not the only one. I would appreciate any info from anyone with the same problem. In February of 06 I had a Banks 6gun tuner with speedloader installed and found it worked better with the banks system removed, sent it back to banks for repair, and then again for replacement, haven't reinstalled it yet. With the banks system installed, dialed down to one, I found out by locking out of OD it ran about 2oo to 500 degrees cooler on EGT and I didn't have the problem near as often.

Yes, a failing CP3 will also cause a 1093, its just not as common.

i'm going to try the fprv first..can i do this myself? i have a shop with all the tools i'm sure

Ppe sells a race version of that valve. It is very reasonably priced. Installing it is not easy but it cured my limp mode problems.. Arm

Shimming is not that bad !!

Worst part to me is getting the glow plug harness bracket off.........on a LLY at least......the bolts for the bracket are under it and hard as hell to get to !!

My FPRV came out with a good tug and a brand new 6pt 18mm wrench......but I have heard of the floks that round them of. Glad I listened to the guys here and got a good new 6pt !

After that you need a vise and the rest of it is pretty straight forward with some descent instructions !!

I will say that I am still having trouble with it.........towing only..........so I am not sure if I should have done my lift pump first.........kinda thinking I should have !!

I always got the P1093 code right from the time I had the truck(stock), they changed everything in the fuel system and still it kept happening. Installed a lift pump 2-3 months ago and have not had a problem since. I also noticed installing the lift pump the surging at idle has gone away as well. I think the design of these trucks not utilizing a lift pump is stupid, why rely on the CP3 to pull enough fuel for the system?

Low speed surging on my big tune does seem to have improved since putting in my lift pump !