I doing some finishing touches on an LS swap I've been working on and I need to figure this out. I have plumbed many LS fuel systems and as far as I know, have the figured out just fine.?.?

Inline Walbro 255, Vette filter/regulator, return less truck rails. KOEO pressure is 75ish while the pump primes and settles around 50 once it shuts off. With engine running I'm seeing around 75 at idle and pressure drops to (???? Maybe in the 50s) during snap throttle in P/N. I haven't checked pressure under load.

It should be 58psi regardless of load. Could the 255 be out flowing the Vette regulator at idle and KOEO?

The truck runs great but I want to get this straightened so that the pump doesn't die young. Also, I have checked this with 2 gauges as a sanity check.

 

I need a quick fix for this if possible. Should I order a 190 LPH Walbro and just swap it out or assume the filter/ regulator I have is faulty and just grab one local and swap it? Btw, the return line is mostly 3/8" hard line to the tank with just a couple feet of -6 nylon braided hose. The truck is a 61 C10 with in cab tank and I just Made up a return line connection for the sender out of 5/16" hard line, drilled a hole in the top of sender and TIG brazed the tube in. The tube is long inside the tank and is submerged in fuel. This couldn't be a problem could it? I figured it would be best to submerge it so it was splattering as it retuned?

 

Pics for reference.

 

Another pic.

 

Another.

 

I'm desperate, been working on this swap since 3/2/2015 nights and weekends. About 200hrs worth and the owner is wanting to make the 8 hr round trip to pay and pick it up this Friday. I am BEYOND burnt out so I want this to happen. Still have some work to do other than this issue but this is the only one that isn't black and white. If I need to order something, it has to be today before I leave work.

 

The vette filter was never intended for that fuel pump...you can man up and buy an actual GM filter or Wix filter and that will help some but its never going to be right

 

Try disconnecting the end of the nylon portion from the hard line and have it empty into a bucket. If the regulator maintains pressure its an issue with the return line. If its still too high then its an issue with the vette regulator.

 

George, there are over 2.5 million posts on this forum relating to guys successfully using parts with other parts that were never intended to be used together. Ie 5.3 + 20psi boost, you get my point, Lol! I'm not being rude, just saw humor and had to point it out! Joking aside, this is exactly what I need to know. If the regulator can't support this pump, I need to get a lower flowing pump STAT. Do you have 1st or 2nd hand knowledge of 255 LPH being too much for the reg? If so, happen to know if a 190 will work with it? Thanks man!

Atomic, yes that is a valid test and believe me I'm kicking myself for not doing it last night. Problem is, I'm still working on much bigger projects on this truck in comparison to the fuel system issue so I haven't dedicated any time whatsoever to resolving it until the 11th hour (today)(last day to order).

If this pump is in fact out flowing the return circuit of the regulator then I need to know what an acceptable flow rate is so I can either order a pump from Summit next day OR possibly find one at a local parts house that is similar in dimension and carries the same fittings as this Walbro.

As always, thanks guys!

 

Yes on several cases.....GM or wix help but the cheaper ones dont handle a 255