p1093 limp mode stock truck

[MASTERSON1172]

hey, i'm workin on a 05 lly for my buddy and i just plugged efi to it and read the codes. i got p1093 the low rail pressure code. my problem is i aint sure were to start ,the fuel filter is changed every oil change and unless it collapsed it should be fine. i'm wondering if it could be a faulty or weak regulater or cp3. or if it's intermidiat electrical. the code was set at 58 mph boosting 31 psi pulling loaded bed of tools and bobcat. so it was in a pickle when it drained the rail which is what i expected but why is a stock truck with clean filter running out of fuel. any help will be greatly appreciated. thanks sorry bout my spelling!

[IdahoRob]

Even stock LLY's had FPRV problems. Most likely shimming the fuel pressure relief valve will fix it.

1093's are caused by fuel restriction before the cp3, or weak relief valve.

[MASTERSON1172]

Thank you sir, I'm glad to hear your input you know these trucks very well, I was looking forward to your input in particular more than anyones. I always fill confident in taking your advice. i will replace the fuel filter again to start fresh and then shim the FPRV. Thanks Again

[FoX BoX RaCiNG]

Bump for an honest guy