LB7: kinda lost at this one need some direction

[Mpsoldier]

04 lb7 injectors are all within spec new fuel pressure regulator and fuel pump. So only 900psi on crank actual vs desire of 4200 but it you give it a quick shot of silicone it fires up. runs perfect rail vs desire all the way to 23232 max. fprv is plugged and return rates on injectors per bank are all within spec, same with cp3. no tuner on the truck only code is a p0404 egr code. Just looking for some opinions on the matter kinda at a stand still. Also runs a cat 2 micron filter brand new filter on the truck.

 

[dirty_max]

you should check fuel return rates on the injectors, and are you loosing prime somewhere?

 

[AKlowriderZ71]

Sounds like it loses prime. No?

 

[jacobdewey]

Possible 1\4 tank issue? Does it have a lift pump? Any changes made to it since it last ran?

 

[Mpsoldier]

you should check fuel return rates on the injectors, and are you loosing prime somewhere?

return rates on each injector bank are fine. It has a raptor fuel system but never had a problem before only recently. no problems with leaks well lift pump doesn't present any.

 

[jacobdewey]

Still could be 1\4 tank issue if tank is under, add 5 or 10 gallons a try again.

 

[NC-smokinlmm]

Sounds like its sucking air on the supply side somewhere or there is excessive vaccum from a restriction...

 

[02greysixer]

What's rail pressure do when driving? Like a 0-60 pull at wot?

 

[Mpsoldier]

sry guys haven't really done much lately screwed up my shoulder. but rail pressure is right on the command no surges or anything out of the ordinary. when doing a wot pull its right at 23k rail maybe like 23100 but still right there.

 

[chevy_dmax]

Will it start after it has sat and cooled off for like 12 hours?

Bill.

 

[steveman09]

I bet the filter head needs to be rebuilt, my primer had a slight leak (vapor leak) at times that would give me weird no starts at times, but once running no issues as the CP3 can suck enough fuel to get past the slight vapor leak but after sitting it would loose prime sometimes. Cost me like 50 bucks in parts from merchant auto and about an hour to fix havent had the issue in 30k miles.

 

[Mpsoldier]

Will it start after it has sat and cooled off for like 12 hours?

Bill.

nope its weird sometimes it will start right up sometimes it wont even if you let the fuel pump turn on for couple seconds before cranking it still wont start . when i get it back i probably going to change out the filter head but then again that's brand new too. I am going to see if it will start off a jug on the side of the motor eliminate the fuel system. to the tank.