OKay guys, I have an 06 sierra denali 6.0 that I have a trick turbo kit on And the problem I am having is its dropping 8-10 pounds of pressure under 7 lbs of boost.
Here is what I have done so far...
walbro 400 pump with submersible fuel line, hotired the fuel pump by running an 8 gauge hot from the plug to the front of truck using a relay, ran 8guage ground to the frame.

The fuel pressure regulator is the factory and is in the bucket with the "lifetime" factory filter.

I am 58lbs at idle and normal driving then as soon as get into boost the pressure begins to drop and reaches 48 lbs under 7 lbs of boost and 5K rpm. Anyone run into this and if so how did you fix it? Thanks

 

You need a return fuel system to fix it.

 

Isn't the factory system a return system?

 

No, yours is a returnless. Reg in the bucket and one line to the fuel rail (no return line from a rail mounted reg). Has no way to add pressure for the extra fuel being used during boost. If you AFR is not dropping, then you're current fuel system is doing the job.

 

I understand that. I want it absolutely right So I will add the returnless sytem. Now I will hunt for the pieces needed. I have a fuel rail with the regulator at my disposal so I will just need to get the line and fittings to do the swap to this. Any suggestions as changing from the existing fuel canister to a canister with a return line or should I just drill the tank or what is the correct way to add the return line to the tank.

 

I added a fuel sender repair line like this from Dorman to the top of the fuel module... drilled a hole and put it in and brazed in place..



That became my new feed line, and used the old one as my return, I took the return line loosened the torx bit off a return type fuel rail I purchased and cut it down and slid a 3/8 type factory quick disconnect line I bought at the store as a repair line also and brazed it on, that way the original factory feed hooked up as the return. I ran a feed line using ptfe braided hose with a factory style filter, but you can do it a bunch of ways... Stock regulator worked good with my 340 lph would rise with boost etc.., but I'm changing it all up when I get back from deployment because I upgraded to a 450 before I left and it's pushing thru the stock regulator so its the opposite issue you have lol.. Just an idea

You cant swap fuel modules if that's what you mean, a lot of guys will go with AN line and use a bulk head type fitting on the top hat of the fuel module as a feed.. The way I posted above will work too