Guest bastaad525 Posted August 3, 2004 Share Posted August 3, 2004 Okay maybe this is being lazy of me I know with some FPR's, I guess only the rising rate ones, you normally run it in line with the stock one, after it in the return line. What I'm wondering, is what about for NON rising rate adjustable FPR's? Last time I installed one of these on my ZX, I completely bypassed the stock unit, took it out of the fuel line completely. What I'm wondering, is would there be any harm or draw back to running a non rising rate regulator inline with the stock unit? This would simplify installation quite a bit, as it's a pain getting to short fuel hoses that go into and out of the stock FPR, this way I could just cut into the long section of fuel hose that comes off the rail... much easier. If I were to do this, I figure I'll disconnect the vacuum line from the stock one, so it wont really be doing anything accept affecting the base pressure, and run that vacuum line over to the new one. Would that work? Would there be any problems with leaving the stock one inline w/o the vacuum line connected? Okay so it's definately lazy of me !! Quote Link to comment Share on other sites More sharing options...
Guest Cronic Posted August 4, 2004 Share Posted August 4, 2004 Never tried it, but I don't believe it would work... If you put it behind the stock FPR, the stock one would limit your fuel pressure, if you put it ahead of the stock FPR, then.... I dunno what would happen. lol. But it wouldn't work me thinks. Quote Link to comment Share on other sites More sharing options...
lilj Posted August 4, 2004 Share Posted August 4, 2004 I know with some FPR's, I guess only the rising rate ones, you normally run it in line with the stock one, after it in the return line. ...? ive never heard of that? someone correct me if im wrong lol.. but i just put a rising rate on my car and theres no other fpr in the car. *clueless* lol =P -jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 4, 2004 Share Posted August 4, 2004 I'm 90% positive the Cartech/BEGI FMU or RRFPR installs inline with, and after the stock FPR. This is because it isn't supposed to do anything at all during normal driving, rather, it is only supposed to affect the fuel pressure when on boost. As far as putting one FPR after another... if the first one (stock one) is set to do nothing (remove the vacuum reference line) I would think it would only keep the pressure from getting any LESS than whatever it would rise to with the hose disconnected, usually about 40psi. Which is fine, I'm shooting for pressures higher than that anyways. But by putting another FPR after that one, I think I could raise the pressure higher than this 40psi, because the second FPR would create it's own restriction, which would vary with the vacuum signal. Quote Link to comment Share on other sites More sharing options...
280z-racer Posted August 5, 2004 Share Posted August 5, 2004 not to hijack the thread or anything but i want to know if using say and FMU, then routing would be fuel pump-fuel filter-fuel rail-stock fpr-to FMU-then back to tank, is this correct?? and my second question is can you run the same vacuum line to both with a T or do they need seperate ones from different lines al together?? Quote Link to comment Share on other sites More sharing options...
lilj Posted August 5, 2004 Share Posted August 5, 2004 what i'm saying is that (not using both fprs..) may be my problem, or it just may be the fact that i havnt fine tuned my afpr yet. my car doesn't like to idle, and without the vac line hooked up to the afpr it won't rev above 1500 rpm. but yeah, thats why i made the comment, because as far as i knew you just popped it after the rail and that was that. -jon Quote Link to comment Share on other sites More sharing options...
cheftrd Posted August 5, 2004 Share Posted August 5, 2004 not to hijack the thread or anything but i want to know if using say and FMU, then routing would be fuel pump-fuel filter-fuel rail-stock fpr-to FMU-then back to tank, is this correct?? and my second question is can you run the same vacuum line to both with a T or do they need seperate ones from different lines al together?? That's correct, and yu can use the same line as long as it's large enough and short enough not to cause a delay in pressure change to the regulators. As far as the other question, running two FPR's in sequence won't change anything. The pressure will only go as high as the highest pressure setting on the regulator with the highest pressure. With a rising rate FPR, it should to go in line after the standard type regulator to work properly. That said, FMU's are not a good choice for fuel enrichment. To double the fuel, it requires four times the pressure; bad for the pump, bad for the injectors, bad for the car if something fails and you have a fire. The EFI system was not designed to run that kind of pressure. Matt Quote Link to comment Share on other sites More sharing options...
280z-racer Posted August 5, 2004 Share Posted August 5, 2004 thanks--someone finally answered my question!! Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 11, 2004 Share Posted August 11, 2004 I dont think I'm going to run an FMU, just a second adjustable FPR in line after the first one. I'm not looking at coming anywhere near double the stock pressure, only looking for about a 10-15psi increase over the stock pressure. I"m going to set it to around 45-50psi at idle. So I'll leave the stock one inline, but disconnect the vacuum signal from it. So it will basically always be set to about 40psi, but the adjustable's fuel pressure SHOULD override that I would think, so I can set my idle pressure higher than 40, and then the adjustable should be the only thing affecting fuel pressure after that point. I may be trying this as early as tommorow, I'll let you guys know what happens. Quote Link to comment Share on other sites More sharing options...
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