HCI2000SS

iTrader: (2)

Okay guys I might have a potential issue here and need some guidance and opinions! Okay I have a Autometer fuel pressure gauge and it reads 50 psi at idle and at normal driving...not sure about WOT psi but could easily find out if necessary. I have a Walbo 255 pump and 42 lb injectors as well. Now it's my understanding that stock LS1 fuel pressure should be about 58 psi. My question/concern here is my fuel pressure where it's supposed to be? I am going to have the car thrown on the dyno this coming Tuesday to verify a/f for my nitrous (it ranged from 11.5 to 12.5 n/a) and to verify WOT timing as well. I am worried that my fuel pressure may be low, and do not want to run into issues with the nitrous now being introduced to the fuel system as well. It seems to run fine n/a though. Any help, opinions, feedback, etc...would be greatly appreciated since I only have a few days to figure this out! Thanks!

Lonnies Performance

iTrader: (16)

Try another gauge first.

Then verify full throttle fuel pressure before trying the bottle.

HCI2000SS

iTrader: (2)

Thanks for the response, but I think I may have found my issue! I took the car for a spin today and verified fuel pressure at WOT, and at hard part throttle driving as well. I also used the gauge to verify pressure during a leak down test. Long story short...I do not have a leak, but at WOT fuel pressure will approach 30 psi right at redline under full throttle. When I nail it at 4000 rpm in 2nd or 3rd (probably would be the same with any gear) It's starts around 40 psi and approaches close to 30 right at redline....that's not good lol Instead of ripping out the whole electrical gauge assembly (not even sure how it's wired in since it came with the car upon purchase) i'm going to start by replacing the fuel filter and see what that does. If that doesn't work (and it's not a faulty gauge) it's either a bad pump, or a issue with the voltage as the rpm's rise i'm told. In which case i'm pretty screwed because the fuel pressure regulator is inside the gas tank along with the pump. And to drop the tank on my ride it appears that I need to remove some of my driver side cat back (which is welded unfortunately) at bare minimum...then we can test the voltage, and then maybe replace the pump if that's what it comes down to. I pulled the part number off my fuel gauge and called Autometer directly, and they said that is one of their top of the line fuel gauges, and they are almost never wrong. I realize that anything is possible though lol. Oh...and another thing here...I called Walbro as well, and they said they do not make a fuel pump for the LS1. I find this rather odd, since I see guys running them a lot on here...so who the hell knows lol. This whole thing is really pissing me off since I was scheduled to put the car on the dyno this Tuesday to check the a/f and WOT timing on the nitrous...no way in hell i'm going to do this if I don't have the correct fuel pressure lol. I'll keep everyone posted

HCI2000SS

iTrader: (2)

Okay I changed the fuel filter today, and it did nothing to change the fuel pressure Bottom line....what is the "most likely" scenario here in everyone's opinion? Fuel pump? Fuel pressure regulator? A voltage issue? I checked my Autometer gauge against one that I rented from Autozone, and it was fine so that's not an issue either. I really think the only way around this issue is trial and error unfortunately lol

Ollie8974

Check for an in tank leak.
Several resent thread of someone having fuel pressure problems.
Turned out to be in tank leaking hose clamps.

HCI2000SS

iTrader: (2)

Oh wow, I never thought of that! Thank you!

HCI2000SS

iTrader: (2)

Okay I went ahead and rented a fuel pressure gauge from Autozone to compare it with mine. It appears that mine is around 8 psi off at idle and light driving. The Autozone gauge shows 58 psi where mine shows 50 psi. Next test was to tape the Autozone gauge to the window and take it for a drive to see if it dropped like my Autometer, and it sure as hell did. So basically my gauge is wrong, but because both gauges showed a corresponding drop there's definitely something else going on here. It makes me wonder if my nitrous gauge is off as well since it's part of the a-pillar pod setup along with the fuel gauge. Gotta look into that now too I guess...geez lol! On to the next step...the fuel tank lol

Hulkls1

iTrader: (2)

Check the relay for fuel pump I had one that and same thing happen put in a new relay and fixed it

HCI2000SS

iTrader: (2)

^^Thank you for that info! I will definitely check that as well!

HCI2000SS

iTrader: (2)

Okay guys I need some help on making a quick decision here, as it's crunch time! In a nutshell...the guy that's going to throw my car on the dyno and verify a/f and WOT timing is extremely booked for like 2 months right now, and my only time to get in is tomorrow. With all that has been mentioned above (58 psi at idle and light driving and 42 at WOT and redline) would you give it a shot on the nitrous and see what happens or no? Now I realize the "right" answer of course lol, but here is what i'm thinking: Say we throw it on the dyno and on a 100 shot it pulls fuel pressure down to maybe 30 psi at WOT. Okay not ideal of course, but maybe it will be acceptable for now...maybe not...at least i'll then know lol. My tuners says that my being at 42 psi at WOT n/a is totally fine for now as well, and he will pull out of it if he detects even the slightest a/f issues or spark knock, or whatever! So here is what i'm thinking...make the pulls...see what happens...then when I get around to it fix this fuel issue whatever it is, and I should then most definitely be fine to spray it without having to go back for for a a/f reading and whatnot since it will be several months before I could even do so anyways. Also keep in mind that I will be running BR7 plugs and pulling timing via my LNC-2000. So let's hear it guys

35th SS

iTrader: (2)

whats your n2o setup?

HCI2000SS

iTrader: (2)

It's a NX single nozzle wet kit. I'm running a MSD digital window switch, LNC-2000, bottle heater, both a nitrous and fuel pressure gauges, and NGK BR7EF plugs. Also keep in mind when I got the car I had it thrown on this same dyno that i'm scheduled for tomorrow to verify a/f only and it was around 11.5 till 5k, and then leaned out to 12.5 from 5k to redline

HCI2000SS

iTrader: (2)

I'm picturing a scenario something like this: We get it on the dyno and start spraying at around 3k...then a/f starts to maybe become unacceptable at lets say 5500-6000 rpm (or whatever) because i'm not getting enough fuel. Or maybe we get some spark know and shut it down. So say a/f, spark and everything is good to this point or thereabouts. Now once I fix this fuel issue wouldn't it likely be safe to assume that a/f and whatnot would be good for the last few hundred rpm or whatever since it was stable up to a certain point before? Is that making sense or am I completely off here lol? This way I get to find my WOT timing, my a/f and/or safe spark up to the acceptable rpm (maybe it will hold all the way...who knows) keep my appointment and not have to reschedule two months later, and whatever benefits that may be relevant here. So tell me what you all think please!

The_Bishop

iTrader: (10)

Fuel pressure issues + nitrous = Boom. Nitrous doesn't forgive, even a little bit.

HCI2000SS

iTrader: (2)

I totally understand that, but i'm not sure how nitrous would be much different than a blower, turbo, bigger motor, or just a stronger a HCI combo...I mean they all would require more fuel since they all would create more power right? I understand that nitrous creates instant hp and tq comparatively, but a blower would draw fuel to work the blower assembly itself, and so on so on...If there is spark know or a/f issues via nitrous, blower or whatever....

HCI2000SS

iTrader: (2)

Well it looks like I might have finally found the problem...I hope lol! It appears that the original owner did install some kind of hot wire kit to boost the Walbro pump that I have. It's not a Ractronix kit or anything...it looks to be either homemade or simply something i've never seen before. I noticed that the bolt that housed the wires and relay switch was very corroded and whatnot, so I simply drilled a new hole, screwed in a new bolt, routed a new wire and clipped the old one. Now fuel pressure still drops but instead of going down to about 38 psi at WOT it's more like 46 at WOT. That tells me it's a voltage issue. Now I noticed the Racetronix kit calls for a for a heavier wire than what I have on there now, so i'm thinking once I have a stronger wire it might solve this damn nightmare lol! As usual...i'll keep you all informed

35th SS

iTrader: (2)

IMO keep an eye on the rear cylinders 7&8 when your on the dyno.single nozzle tend to lean out those cylinders.thats why I switched to a plate setup.

HCI2000SS

iTrader: (2)

Alright, good info to know! Thanks!

The_Bishop

iTrader: (10)

The big difference is when you spray nitrous, you are injecting a powerful oxidizer. If it can't use fuel to oxidize, it'll eat your pistons.

HCI2000SS

iTrader: (2)

Okay more info here, and have hopefully solved my problem finally lol! I went ahead and pulled my fuel pump yesterday, and realized the idiot had a Walbro 190 in there and not the 255 like he said was in there. So I look up the flow capacity of the 190 and it says it's maxed at 450 hp...and that's at the flywheel. What kind of idiot puts head, cam, and nitrous on a LS1 and puts a pump like this in here lol...plain *** stupid lol!! This would explain why my fuel pressure is dropping more and more as I hammer the throttle. So anyways i'm going after the 255 since it's good to 650 hp according to Walbro. Now I do have two questions though: First, does anyone know if the 255 and 190 have the same exact dementions? Since the bucket was modified to fit in my current Walbo i'm assuming the new one must measure the same in all aspects. Secondly, have any of you dealt with a company called Tank? They sell the Walbo pumps and the fuel sock (which I want to replace as well) and claim to have authentic Walbro pumps and not the stupid Chinese knockoff brands. If you all have any other recommendations on where to buy the pump and sock please let me know. The one I have now is the GSS 242 and the one I want is the GSS 340