LB7: Low Rail Pressure code after ported fuel rail fitting & bullet

[TRUBBS]

we ported my buddies fuel rail fittings and the little bullet deal inside the rail last night, did it to 5/32 like all the other LLY+ trucks we've done, but this morning he had a code come up for low rail pressure.
truck is a 2002 gmc lb7 with brand new II 50hp injectors,fass pump and race evo along with of course intake and exhaust.

wondering what gives?
we monitored my buddies lly with a scan gauge and his rail pressure went up after we did his rail so i didnt think this lb7 would drop?


also, he said it took a little bit of cranking to get it to start this morning as if it had lost prime.
wondering if the FPRV could maybe be a cause of this?

 

[IOWA LLY]

Sounds like there was still air in the system. Or maybe something has a leak now....

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[TRUBBS]

All we took of was the rails, so if there was a leak it in my mind wouldn't start as it wouldn't build any rail pressure & if it did it should spray diesel out.
I got a spare fprv that I shimmed with 5 washers from the hard wear store.
If the problem continues I'll try swapping it in

 

[djforrest119]

LB7's have larger rails to start with and shouldn't need to be ported, especially with those minor mods. Just my .02

 

[Hot COCOAL]

Sounds like the CP3 is getting weak....

50hp tips, a program and ported rails, both rails?

Low rail code sounds like a feasible issue with those mods to me, without something like EFI Live it's hard to say what your tuning is demanding for fuel, and those mods "can" move allot more fuel than an old cp3 is gonna spit out

How many miles are on this truck?

 

[TRUBBS]

LB7's have larger rails to start with and shouldn't need to be ported, especially with those minor mods. Just my .02

they do have large rails, but that bullet thing has a tiny tiny hole in it to feed through.

Sounds like the CP3 is getting weak....

50hp tips, a program and ported rails, both rails?

Low rail code sounds like a feasible issue with those mods to me, without something like EFI Live it's hard to say what your tuning is demanding for fuel, and those mods "can" move allot more fuel than an old cp3 is gonna spit out

How many miles are on this truck?

yes both rails were done as lb7's are individually fed and require both to be done when doing the mod. cant do just one like LLY+ trucks
the race evo seams to be asking for a lot of fuel as his truck runs very strong. holds rail psi fine in the upper rpms it was just on hard start that it threw the code.

i know the lb7s arent usually known for fprv issues but the ones that do have it seam to be the early ones like his.
might just still had some air in the rails as the hard start/code came the morning after the rails were done and we only drove it a few hundred yards and didnt get on it hard cuz it was raining. hasnt had the code come back yet so i think i was just jumping the gun getting all worried to soon. if it comes on again i have a spare fprv that ive shimmed up and is ready to go in.

truck has like 130k-ish miles