Holty

iTrader: (6)

Its been months now and i'm still having fuel pressure drop at WOT causing severe lean conditions. I thought the magnavolt was the answer, but its not. I think i found the answer though. I just talked to a Magnuson rep on the phone and found that i can take out my stock in-tank pump and replace it with a Walbro GSS340 (255lph) pump. He believes i can bolt this pump in with no modifications and have no problems at all. I've already replaced my magnuson supplied in-line pump once and i think its going bad again. The thing is SCARY loud when it gets hot. I know they are noisy to begin with though but i believe that my stock in-tank pump is going bad and putting too much stress on the in-line causing it to overheat. i should be getting word back later today about the 255lph in-tank pump and will be ordering it right away. Then once i replace the in-tank, i'll replace the in-line again with a Walbro GSL392 (255lph). This way fuel pressure issues will be a thing of the past.

yes, i do realize i'm a '03 truck with the return fuel system. the magna rep said that does not matter and i can upgrade my in-tank pump to the walbro unit with no problems.

Whippled 496

iTrader: (4)

well, i think your goin to run into the same issues as me. I started to do this and ended up buttoning everything back up again because i would have had to cut the bucket, and modify the filter to get it to work. Even then, you lose some of the benifits of having the bucket in the first place. It wasnt worth it to me and i decided im not going to mess with it until they have a direct replacement. I realize mine was not the same part number as yours, but i am pretty sure they are all basically the same. Here is the thread i started when i had these issues.....

https://www.performancetrucks.net/fo...d.php?t=359939

I assume we have the same bucket and fuel pump setups since we are both 2003.

Holty

iTrader: (6)

so how did you fix your problem then?

Whippled 496

iTrader: (4)

Found out i really didn't have a problem. I was installing the pump as a precaution, just in case i needed it. With 6psi, 44lb injectors and my stock pump....i still have 60psi at idle and 65+psi at WOT with no drop outs. Installing the pump would have been a nice backup, but not at the sacrifice of cutting my stuff all up. Wish someone had a direct swap without losing the functionality of the bucket! Maybe you should get an 8.1L pump and see if works for you...it would be a direct swap....just an idea.

Holty

iTrader: (6)

so your saying that you have a 2003 6.0 LQ9 and you see 60psi at idle? and 65psi at WOT? cause i don't see anywhere near that, nor have i ever. the most i see at idle is 55psi and at WOT i see 60-62psi. but the problem is holding that psi at WOT. 80-90% of the time, i'll see 62-63psi at WOT, then it drops drastically into the low 50's and then "dances" everywhere in between. during this time, my wideband goes from 11.4 a/f to 13.5+ a/f ratio.

Whippled 496

iTrader: (4)

Nope, im saying i have an L18 8.1L 496 with a whipple supercharger at 6psi. And yes, those numbers i stated are what i see consistantly, and verified in several EFI logs at WOT. No drop outs what so ever. I have about a 95% IDC at WOT and see about 1.4X G/cyl at WOT also. No problems yet, but i have to imagine im right on the edge.

Holty

iTrader: (6)

ok, so we have completely different trucks and motors so i'm sure our fuel systems are different.

Whippled 496

iTrader: (4)

I doubt it, i bet they are the same. I cant verify it of course, but they make these systems very similar. I bet you have the same style bucket, pump, evap can, and everything. Maybe you just had a weak pump from the factory? Who knows, but i bet if we dont have the exact same fuel setup, they are very very close. We both have return style systems with the FPR on the rail....only thing different is probably the injector size. Im not trying to influence your decision one way or another, just giving you a "heads up" on what you may be in for.

Whippled 496

iTrader: (4)

i am assuming this based on the fact that we have the exact same year truck. I have seen some buckets from the 6.0L guys (not sure if they were LQ4 or 9) but they looked identicle to what i have.

wkdivr

iTrader: (8)

Holty, didn't you post awhile back you were seeing your IDC going pretty high? Some 6.0L guys have had to replace their injectors with the Lightning ones (I think). Zippy has some really interesting thoughts on this, check with him.