I am having problems since i changed my fuel system. initially I had a stock fuel pump with a bosch 044 inline, with 42 lb injectors and a modified stock fuel rails, looped on both ends. with that setup i had no loss of fuel pressure stayed at about 60 regardless of boost level ( i have a turbo on my truck) a couple months ago i built a forged engine for my truck, i decided to go wth larger 65 lb injectors, and an aeromotive 340 in tank, got tired of the noisey bosch pump. so during tuning truck was going lean i had 65 psi and when going intoboost fuel pressure dropped. so i thought this was a voltage issue, i installed a reacetronix wiring kit, same deal. thought maybe a fuel level intank issue, filled up same issue. so i decided to go back to a stock intank and a walbro 255 inline, got that all done today and i have the same issue. i can be driving down the road at maybe 50mph or so and ease into it and anything above about 3 psi fuel pressure drops to like 30 psi. I have an aeromotive regulator that is boost referenced and can adjust it from 55 to 70 psi at idle and it makes no difference to my fuel pressure loss issue. I am wondering if it could be an isssue with the fuel rails, thats really all thats left. any ideas or suggestions would be appreciated. ive been fighting this for almost 2000 miles and really wanna be able to get on it in my truck.

 

Anyone have any ideas?

 

Get a video of it. Watching the gauge would help to diagnose.

 

Ill try its ok till about 5 psi then it drops to about 35 40 psi and I get out of it it shows up to 13 on my wideband before I get out of it

 

You need more pump, preferably an in-tank that flows about double your 255, without butchering the stock bucket so that you don't have to keep your tank above 1/2 full.

 

I don't think I need more pump a lot of guys are running just a 340 or a 255 my previous setup was a stock intank with a bosch 044 inline and never had an issue. I can try putting the 340 back in the tank I suppose with the 255 inline.

 

I just pulled my aeromotive 340 out. They over heat. Mine would get so hot that it would completely shut down. I'd have zero fuel pressure. It was a new pump had it maybe 3 months. I thought at first that my turbo was over beating the rails. So I switched out my stock rails for aftermarket ones, also did a return system, so fuel would flowing all the time threw the rails. Still I was left on side of the road because the fuel pressure dropped to zero. I had a walbro 255, so I threw it in and no more over heating pump. My fuel pressure in boost was under 40psi. So I ordered a walbro 400 and a Hobbs switch. Now the walbro 400 is primary pump and the walbro 255 comes on at 4psi.
I'm not sure why you have so little fuel pressure on such low boost.
I'd check for leaks on all fittings,
Or put the 044 back in. See if your fuel problem is fixed