Bernardd Posted March 15, 2007 Share Posted March 15, 2007 Where is the fpr mounted? I know a few guys have had problems with the fpr if it's mounted too far away from the fuel rail. The cases I know of had the fpr mounted on the firewall or fender. Quote Link to comment Share on other sites More sharing options...
X64v Posted March 15, 2007 Author Share Posted March 15, 2007 Matt - Thanks for checking the whole log to make sure there was nothing that the untrained eye would miss. Cygnus - That's the conclusion I came to as well. I have been testing and bypassing every part of the fuel system that I can think of. I will try bypassing the 2nd fuel filter when I get a chance, as well as making sure the feed line before the pump isn't collapsing. Bernardd - It's mounted on the intake manifold, with perhaps 8 inches of fuel line between it and the rail. Quote Link to comment Share on other sites More sharing options...
X64v Posted March 16, 2007 Author Share Posted March 16, 2007 Alright, I'm about ready to file this under the straingest car problem ever... I just did some flow tests on the system (5 gallon gas can w/full mark, and a stopwatch). Free flow (tank-->prefilter-->pump-->filter-->gas can) I got 60gph (did 5 gallons in 5 minutes spot on) Pessurized to 36psi (tank-->prefilter-->pump-->filter-->hardline-->fuel rail-->fpr-->gas can) I got 49gph (did 5 gallons in just over 6 minutes). The second test is running exactly like the car runs, through the same routing, everything. The feed line did not collapse or even seem weak during either test. So this means there's no blockage, no restriction. The only thing I can think of that hasn't been discussed is that I'm not running a fuel damper like the ones that came on the cars originally. I was pretty sure they weren't necessary, but are they? EDIT: I didn't like the fact that my first free flow test didn't run through the hardline and fuel rail, so I repeated the test, but ran it through them as well... Free flow (tank-->prefilter-->pump-->filter-->hardline-->fuel rail-->gas can) 60gph as well (came within two or three seconds of the original free flow test, which is within my margine of error for shutting off the pump at the 5 gallon mark). Quote Link to comment Share on other sites More sharing options...
z-ya Posted March 17, 2007 Share Posted March 17, 2007 I'm perplexed. No, the damper is not required. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted March 17, 2007 Share Posted March 17, 2007 could it be a faulty FPR? Quote Link to comment Share on other sites More sharing options...
David K Posted March 17, 2007 Share Posted March 17, 2007 Are you using the stock 240z fuel tank? Quote Link to comment Share on other sites More sharing options...
veritech-z Posted March 17, 2007 Share Posted March 17, 2007 Are you using the stock 240z fuel tank? I was wondering that also, could the fuel be sloshing away from the pickup under load? Have you tried a completely full gas tank and see if the condition persists? Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted March 17, 2007 Share Posted March 17, 2007 Sounds more like an electrical problem.. Wire Your pump directly to the battery and go for a drive. Quote Link to comment Share on other sites More sharing options...
X64v Posted March 17, 2007 Author Share Posted March 17, 2007 Yes, it is a 240 tank. However, it does it with a completely full gas tank, and also sitting still in neutral. The FPR is giving me 36psi while the engine is not running, and I'm getting that 36psi in between injector pulses (or so I would guess, I couldn't time it to be sure). This happens free revving as well. I wonder what I could find out if I rev it with one hand and then pinch the return line with the other... I will try wiring it directly to the battery, though I doubt this is the problem since the fuel pump wiring is the same now as it was with the carbs, and I never had any trouble then. Otherwise, I'm stumped. Hopefully braap will chime in and tell me why it's not working with two pages of fluid-dynamics... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted March 17, 2007 Share Posted March 17, 2007 What kind of injectors are you using. I am beginning to think it may be the injectors reaching some sort of "resonance". Quote Link to comment Share on other sites More sharing options...
X64v Posted March 17, 2007 Author Share Posted March 17, 2007 I am currently running cleaned/flow tested 338cc ford cfi injectors. It also did the exact same thing with 25 year old 19lb n/a zx injectors as well. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 17, 2007 Share Posted March 17, 2007 Running two groups of three on INJ 1 and INJ2 and alternating them--one squirt or two per cycle? I have noticed a BIG difference in the way these cars run depending on how the injectors are staged and how many squirts you use to inject the fuel. Anything that keeps the fuel pressuresteadier normally helps with the way the vehicle runs. 1FastZ's car had massive fluctuations on his ITB setup, until we switched from 'simultaneous' to 'alternating' and went from one squirt per cycle to two squirts. That steadied the Fuel Pressure so the thing really didn't move appreciably. This will keep the FPR from beating itself to death trying to regulate the pulsations as well. You don't need the pulsation dampner, but it doesn't hurt anything, either. JeffP recently added an aftermarket dampner on his rail because the 750cc injectors batch-firing was doing odd things to his fuel pressure, and it WAS showing up in his O2 Datalogs while on the Dyno. I'd be curious to see if it gets better switching Simultaneous and ALternating, and going to 2 squirts per cycle. Some cars will not run it gets so bad until the settings are correct. Quote Link to comment Share on other sites More sharing options...
X64v Posted March 17, 2007 Author Share Posted March 17, 2007 Two groups of three, simultanious, two squirts; what I saw as the standard for running MS on a stock-manifold L6. Would the engine run on alternating? Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted March 17, 2007 Share Posted March 17, 2007 Mine are on alternating using both INJ driver circuits wired like stock with OE resistors. Since you're using the 240z tank, what line are you using for fuel source and return? (sorry if you answered that earlier). Many people switch the source line to the return line since it is bigger in diameter in non fuel injected Zs that were converted to fuel injection. Mario Quote Link to comment Share on other sites More sharing options...
X64v Posted March 17, 2007 Author Share Posted March 17, 2007 Stock 5/16" feed, emissions hardline for return. I'm getting well over double my needed flow through the lines, so they're not a problem. I'm bored, and it's nice out (~78 degrees, gotta love southern arizona), so I'm going to go try out setting injector staging to alternating. Quote Link to comment Share on other sites More sharing options...
X64v Posted March 17, 2007 Author Share Posted March 17, 2007 Nope, alternating made it run worse. Still did the exact same thing at the exact same rpm, but it wouldn't run worth beans under 2k rpm, either. Quote Link to comment Share on other sites More sharing options...
Noddle Posted March 17, 2007 Share Posted March 17, 2007 a stupid question, your tank does have a breather ?, and not creating a vacuum Nigel Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 17, 2007 Share Posted March 17, 2007 I've never tried tunning with a narrow band but looking at your log you look really lean when the problem occurs based on the .4-.5 volts. That would put you in the 14-15:1 range (guessing based on voltage), way too lean for WOT. Your duty cycle also seems low, but I'm not used to seeing duty cycle on n/a motors with larger injectors. I don't know what your fuel map looks like but I would save it and make another one and add 5 or 10 to it above 80 kpa and see if your O2 number go up. Quote Link to comment Share on other sites More sharing options...
X64v Posted March 17, 2007 Author Share Posted March 17, 2007 Yes, you are certainly correct, I am running lean there. I'm still running the same fuel map that I just stole from someone else to get the car running. I never bothered to tune the rest of the map because it was just hitting that wall really fast anyways, so I'm not under WOT very much anymore (which really blows...I miss dropping a few gears and flooring it to pass people and stuff). And yeah, my duty cycle is way low. I bought these injectors with the intention of adding a turbo in the near future. I only need maybe 180cc or 200cc injectors for this engine running n/a. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted March 17, 2007 Share Posted March 17, 2007 maybe it's time to post your msq file and versions so we can check them out. It can't possibly be going into flood clear mode can it? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.