What would cause a massive spike in FP? We are talking 125+ psi
New Walbro 255 lph, ATi inline pump and an Aeromotive Adj. FP reg.
Spiked to 125+ and blew the Quick connect OFF the fuel filter!
If i pull the fuse for the inline pump, it holds at 40 psi running....
If i just turn the key on, it goes to 40, pump stops and it drops rapidly....If it's running at 40, it will creep to 60...What's left? Bad FP reg? FMU? I changed the wires, plugs and in tank pump to cure "breaking up" under load......and it STILL won't hold rail pressure and "breaks up".....
I'm at the end of my rope.....
anyone?

 

From what I have read in other posts in this forum, most people ditch the ATI FMU because of unpredictable behavior....kind of like what you are experiencing. Anyone else think of something?

 

You dont need a 255, fmu and a inline. How much boost? I pushed 12psi in florida with a 255 and a BAP.

 

Thanks for the replies guy's...I only running 9 psi...and what's a BAP???
When i got home from work tonight i fired it up on the intank pump only. I then removed the vacuum line from the FP reg. and fuel pressure DID NOT CHANGE ....Huh?....
Looking at the FMU, does anyone know which line runs to the return on the fuel rail?....Center or bottom?
I bought this kit used with lines already on the FMU, both with male fittings and hooked them up accordingly....Male on the end of 1 hose, female on the other, so my install book doesn't tell me which ones which, because they call a female fitting on one, and a male on the other....
I pulled the vacuum line from the FP reg at the manifold and it was dry....Man, this is driving me nuts!.....I'm about ready to throw in the towel....

 

Dont give up so soon. If your running a 255lph intank pump and a ati inline pump in conjuction with a fmu and a adjustable fpr. imo thats a little much, What I would do is ditch the inline pump as im pretty sure thats causing a restriction, also ditch the fmu as that could be causing problem as well especially if you have an adjustble fpr with a vacume port. Your afpr will act as as fmu as boosty rises your fp will go up in a 1:1 ratio there fot taking the place of your fmu. btw, how do you know your fp is siking to 125?, Ive only seen fp guages go up to 100psi. I think all the extra stuff you have conencted to your fuel system is causing your problem.

 

I would also ditch the FMU, its overkill unless you have really small injectors??? BTW vortech told me the T-rex was not a restriction when used inconjuction with a 255L. anyone agree/disagree?