joeyg Posted November 29, 2009 Report Share Posted November 29, 2009 (edited) What should the fuel pressure be when I'm in a boost (7 psi centrifugal blower)?stock... fuel pump and injectors... FMU and operates properly. Oh and I got an 05 GTO and put in a TVS1900. Love it! That is Black Bear tuned and so will the SSS when I'm close to having the fuel sorted... Edited February 1, 2016 by finallyss (see edit history) Quote Link to comment Share on other sites More sharing options...
misterp Posted November 29, 2009 Report Share Posted November 29, 2009 What should the fuel pressure be when I'm in a boost (7 psi centrifugal blower)? stock... fuel pump and injectors... FMU and operates properly. Hmmm well in theory 58psi + 7psi = 65psi! Set your fuel pressure to 58psi when the engine isn't running, and the fuel pressure should rise and fall in direct line with observed boost/vacuum. If it's within 2-pounds that's usually close enough to tune around. Mr. P. Quote Link to comment Share on other sites More sharing options...
dozer Posted November 29, 2009 Report Share Posted November 29, 2009 What should the fuel pressure be when I'm in a boost (7 psi centrifugal blower)? stock... fuel pump and injectors... FMU and operates properly. I would not tune via fuel pressure at this point and get a wideband on that thing that way you can dial your FMU to get the proper Air Fuel Ratio under boost. Visit My Website Visit My Website Visit My Website Quote Link to comment Share on other sites More sharing options...
misterp Posted November 29, 2009 Report Share Posted November 29, 2009 He's right - I misread, I saw 'FMU' but thought 'FPR' lol. Quote Link to comment Share on other sites More sharing options...
joeyg Posted November 30, 2009 Author Report Share Posted November 30, 2009 Yeah I got a wideband on the way. But this FMU doesn't appear to be adjustable, unless it's the same as the ones I saw on the Vortec site... cal kits. I'll dial in the LTFT's and then bump up the WOT when needed. There is SOOOOOOOOOOO much more to this crap I've got going on. long story short... when I go full throttle and boost kicks in, the fuel pressure goes from like 65 lbs (thanks to the FMU doing it's job), then the pressure drops to 40 lbs and of course leans me out and 4500 rpm is too much. I need to know if 42 or 44 lb injectors would be enuf or do I gotta do a new in tank fuel pump or both. I don't need things to be the most expensive, but doing it ONE time would be cool. Anyone had luck w/ Ebay and the fuel injectors or pumps? Quote Link to comment Share on other sites More sharing options...
dozer Posted November 30, 2009 Report Share Posted November 30, 2009 (edited) Thats enough injector for 6-7psi but will your hand held let you change IFR for thoses injectors? So your FMU is only boost ref and bumps FP as boost increases. Some are boost ref and adjustable. You might as well do the pump to these guys have booth pumps and injectors for your truck Racetronix. Yeah I got a wideband on the way. But this FMU doesn't appear to be adjustable, unless it's the same as the ones I saw on the Vortec site... cal kits.I'll dial in the LTFT's and then bump up the WOT when needed. There is SOOOOOOOOOOO much more to this crap I've got going on. long story short... when I go full throttle and boost kicks in, the fuel pressure goes from like 65 lbs (thanks to the FMU doing it's job), then the pressure drops to 40 lbs and of course leans me out and 4500 rpm is too much. I need to know if 42 or 44 lb injectors would be enuf or do I gotta do a new in tank fuel pump or both. I don't need things to be the most expensive, but doing it ONE time would be cool. Anyone had luck w/ Ebay and the fuel injectors or pumps? Edited November 30, 2009 by dozer (see edit history) Quote Link to comment Share on other sites More sharing options...
joeyg Posted November 30, 2009 Author Report Share Posted November 30, 2009 (edited) 1- Thats enough injector for 6-7psi but will your hand held let you change IFR for thoses injectors? 2- So your FMU is only boost ref and bumps FP as boost increases. 3-Some are boost ref and adjustable. 4-You might as well do the pump to these guys have booth pumps and injectors for your truck Racetronix. 1- yes, I can change injector slope for cruise, I get that straight and then yes we can also adj for WOT in three ranges. If I can't get it dialed in, they'll write me a custom tune for free when I tell them what the prob is. 2-Yes. 3- Boost ref, but I don't see any places to adj. I really don't need to be able to either tho... here's why I hooked up a calibration electronic device at work and applied 7 psi to the FMU line with the engine idling, fuel pressure went up about 14 psig gradually. I did that cause at around 4k RPM the fuel pressure would drop to around 40 lbs actually driving her hard. That told me it's not the FMU, or the injectors (and I ohm'd them and all were good). Soooooooo That's why I was asking people what their fuel pressure was under boost I also found that my Autometer boost guage is off by -.5 psi, by using that cal thingy (that's for the old lady). 2 leaks too that are fixed too I just wonder if I can richen up the upper end and be good. It really does seem like more is needed, cause even if I do that, seems as if the pressure and/or flow is not there (potentially). Ok, wiating on suggestions for pump choice or injectors and what order... probably pump first , man I HATE dropping tanks! Ok, I went to that Racetronics and didn't see a pump for the "SSS". So does the LT1 work for our vehicles? Direct replacement if so? Edited November 30, 2009 by finallyss (see edit history) Quote Link to comment Share on other sites More sharing options...
SSplaytoy Posted November 30, 2009 Report Share Posted November 30, 2009 1- yes, I can change injector slope for cruise, I get that straight and then yes we can also adj for WOT in three ranges. If I can't get it dialed in, they'll write me a custom tune for free when I tell them what the prob is.2-Yes. 3- Boost ref, but I don't see any places to adj. I really don't need to be able to either tho... here's why I hooked up a calibration electronic device at work and applied 7 psi to the FMU line with the engine idling, fuel pressure went up about 14 psig gradually. I did that cause at around 4k RPM the fuel pressure would drop to around 40 lbs actually driving her hard. That told me it's not the FMU, or the injectors (and I ohm'd them and all were good). Soooooooo That's why I was asking people what their fuel pressure was under boost I also found that my Autometer boost guage is off by -.5 psi, by using that cal thingy (that's for the old lady). 2 leaks too that are fixed too I just wonder if I can richen up the upper end and be good. It really does seem like more is needed, cause even if I do that, seems as if the pressure and/or flow is not there (potentially). Ok, wiating on suggestions for pump choice or injectors and what order... probably pump first , man I HATE dropping tanks! Ok, I went to that Racetronics and didn't see a pump for the "SSS". So does the LT1 work for our vehicles? Direct replacement if so? Glad to see yoyu are getting this all worked out finally. Stepping up to 42# injectors and putting in a Walbro 255 in the tank should help you out. Dropping the tank sucks, but if you hate it that bad, you can always take off the bed Quote Link to comment Share on other sites More sharing options...
idahoBLKss Posted November 30, 2009 Report Share Posted November 30, 2009 yeah i got the 42-44 lb injectors and a intank walbro 255 ordered from magna charger , but your an '03 and your fueling system is a lil different then the '04 and newer so i would ask some one that has one on a '03 and see what they are running. Quote Link to comment Share on other sites More sharing options...
joeyg Posted November 30, 2009 Author Report Share Posted November 30, 2009 Glad to see yoyu are getting this all worked out finally. Stepping up to 42# injectors and putting in a Walbro 255 in the tank should help you out. Dropping the tank sucks, but if you hate it that bad, you can always take off the bed Yeah, thanks a lot, after all is said and done... time for a compression check too. Ha, if I take the bed off I'll leave it off for weight reduction Are these walbro pumps a direct replacement? I hope so yeah i got the 42-44 lb injectors and a intank walbro 255 ordered from magna charger , but your an '03 and your fueling system is a lil different then the '04 and newer so i would ask some one that has one on a '03 and see what they are running. ok, thanks and on to research. I'm monitoring this regularly so anyone with a similar set up PLEASE chime in. Quote Link to comment Share on other sites More sharing options...
SSplaytoy Posted November 30, 2009 Report Share Posted November 30, 2009 I have an 03 with the return system. I ran a radix with the 42# injectors, a 255 walbro in-tank, and the inline. I was also running slightly more boost. I ran lean, but that was due to tuning issues. The pump isn't a direct fit. You have to cut and splice wires, clamp on a new piece of hose, and drop it back in. It isn't that hard, nor is the inline pump. Just wire the inline pump up to a relay with the ignition. Quote Link to comment Share on other sites More sharing options...
joeyg Posted November 30, 2009 Author Report Share Posted November 30, 2009 I have an 03 with the return system. I ran a radix with the 42# injectors, a 255 walbro in-tank, and the inline. I was also running slightly more boost. I ran lean, but that was due to tuning issues. The pump isn't a direct fit. You have to cut and splice wires, clamp on a new piece of hose, and drop it back in. It isn't that hard, nor is the inline pump. Just wire the inline pump up to a relay with the ignition. Seems like the 03 is the black sheep. I'm having a hard time even finding a Walbro 255 in tank. I don't mind cut/splice etc... I really just want to get it out of the way. By the time I get one, I'll be shoveling the driveway for the swap. I was on the magnacharger site (VERY HELPFUL) and they only have the inline for the 03. I really don't plan on going any higher than the 7 lbs boost, so I think the in tank 255 would do the trick. Then if I do a cam, I can add an in line if need be. And the relay thing is explained well on their site too. Quote Link to comment Share on other sites More sharing options...
SSplaytoy Posted November 30, 2009 Report Share Posted November 30, 2009 Seems like the 03 is the black sheep. I'm having a hard time even finding a Walbro 255 in tank. I don't mind cut/splice etc... I really just want to get it out of the way. By the time I get one, I'll be shoveling the driveway for the swap.I was on the magnacharger site (VERY HELPFUL) and they only have the inline for the 03. I really don't plan on going any higher than the 7 lbs boost, so I think the in tank 255 would do the trick. Then if I do a cam, I can add an in line if need be. And the relay thing is explained well on their site too. Call them up and see if they have it or check out a few local performance shops around you to see if they have one. Quote Link to comment Share on other sites More sharing options...
dozer Posted December 1, 2009 Report Share Posted December 1, 2009 (edited) Racetronix 255lph pump here is the pump you need. be sure to select the 255lph and not the 190lph in the drop down box. Edited December 1, 2009 by dozer (see edit history) Quote Link to comment Share on other sites More sharing options...
8 UR HMI Posted December 1, 2009 Report Share Posted December 1, 2009 ebay or magnacharger. they both have walbro 255's i ran 9lbs on my turbo system with the walbro and 42lbs and an inline seeing 53-55 psi for fuel. the fuel pump is not hard at all. dropping the tank takes the longest. Quote Link to comment Share on other sites More sharing options...
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