zsteelman Posted January 18, 2011 Share Posted January 18, 2011 So I have been working on my 1977 280z trying to get things lined out to start. I will start from the back and work forward. Currently pumping gas out of a 5 gallon tank sitting on the floor, fuel return is feeding into a glass jar to detect any junk that may have came through. Cleaned out hardlines with shopvac using a combination of blowing and sucking carborator cleaner through the lines. Replaced all fuel lines with new line from the pump to the injectors. Ignition has spark at all plugs, the car will start if I spray starting fluid into the intake. Tested compression and have about 100 across all cylinders. Started checking the ECU at the plug to determine if the lines were all getting solid power. So far all of the tests worked successfully (a note: the EFI-Bible confused me until I realized that the 77 ecu plug is slightly different. Next step was to test and see if the injectors were getting signal. Hooked up a light to the injector plug, cranked the car and got signal pulses on all injectors. That rules out the wiring and ECU problems. I have fuel pressure at the injectors, when I disconnect the starter plug and turn the key to start the fuel pump engages. When I push the AFM flapper, the fuel pump engages. If I use the starting fluid I can get the car to rev and crack over. However it will not stay running which leads me to believe that I am either loosing fuel pressure so much that I cannot get fuel for the car or that my injectors are clogged. I put a 12v source to the CSV and heard a click that was expected, loud and clear. However when trying to put a 12v source to the injectors (The injector harness was reading 12v on the positive) I did not get a click, I barely got any spark running to the terminals at all. Before I pull off the fuel rail again to clean the injectors any way to test them for sure to make sure that they are bad? I didn't remove the injectors the first time because there were a few stripped screws that I didn't want to mess with at the time. Thanks for the help Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted January 18, 2011 Share Posted January 18, 2011 you need to get an actual fuel pressure reading not "i heard the pump run". somewhere in the low 30's pic is a low cost pressure check you can make with parts from hardware store and a cheap oil pressure gage. goes between filter and fuel ring. is the fuel return coming from the fpr or did you run it direct to your container. no fpr low fuel pressure on ring lo press she no workee. use some deoxit by caig to clean the ecu, afm and tps electric connectors. if battery is weak or cables corroded z's don't like low voltage and all sort of electric gremlins as electronics don't work correctly. load test battery new cables. Quote Link to comment Share on other sites More sharing options...
zsteelman Posted January 18, 2011 Author Share Posted January 18, 2011 The battery is brand new (Purchased a week ago). I am picking up a fuel pressure gauge this week to test and see if I am getting enough fuel pressure. I do believe that it may be an issue because I am not getting fuel flow back through the return line from the FPR as expected. The lines have all ben cleaned and flow, but still nothing coming back. As for the electronics, all connectors were cleaned with QD electrical cleaner and a brasswire brush to eliminate green meanies. thanks Quote Link to comment Share on other sites More sharing options...
zsteelman Posted January 27, 2011 Author Share Posted January 27, 2011 Ok finally got an update. I purchased an oil pressure gauge and built one as per your recommendation roger. With the starter trigger disconnected I turned the ignition to get the pump running and was able to get a stable 30psi, however I need 38 correct? This is the reason that I am not getting fuel pumping back from the FPR because it is never opening. However, here is the question, I can continously run the pump and it will not pump past 30 psi, however I do not have any leaks in the system and no fuel flowing backwards out of the pump that I can tell. Do you guys think it is a bad pump that will not pump past the 30psi and should be replaced? As I was looking around the car I also tested the AFM via the FSM - All tests came back positive, rules that out. Tested the Idle Switch and Full Throttle Switch via the FSM - All tests came back positive, rules that out. I tested the continuity across the injector terminals and they were successful as well, along with the pulsing lights during the crank tests I feel the electrical portion is ruled out on the injectors, but again I can not hear them clicking even when giving a 12v power source. Any clues? I figured that the car would atleast stumble start with low fuel psi. Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted January 27, 2011 Share Posted January 27, 2011 (edited) it should run with 30 but if you are getting no return from the fpr something is wrong. the whole premise of the system is that the fuel pump delivers way more fuel than the engine can consume. the fpr is a constant pressure regulator which senses the ring pressure and bypasses to the gas tank enough excess fuel to maintain pressure on the ring. so in my opinion seeing 30 psi with no return from the fpr is proof that the fuel pump is not delivering enough volume to the system to operate. where did you get the 38 number if I remember correctly it runs like 30-36 but with no return I believe your pump is faulty. another cause might be ignition timing. do you smell raw gas at the exhaust when trying to start it. i'm more familiar with the s130 setup but i believe the system basics are the same for the earlier FI cars. Edited January 27, 2011 by roger.svoboda Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted January 27, 2011 Share Posted January 27, 2011 you do have the fsm don't you. Quote Link to comment Share on other sites More sharing options...
zsteelman Posted January 27, 2011 Author Share Posted January 27, 2011 Yes I do have the factory service manual and that is how I started diagnoising things. I went through the ignition system first, I have spark, the car will start on starter fluid and stumble for alittle while off of the starter fluid but will not continue to run. The FPR should only open when the fuel ring goes above the 36ish psi so that would be the reason that I am not receiving any fuel back to the fuel return. The lines are clear as they were cleaned before reinstall of new hoses and cleaned fuel rail as well. I have not checked the ignition timing as I assumed since the car would stumble on starter fluid that the timing was close enough to enforce the compression strokes and idle, even if roughly. All of the electical connections are good, tested the entire ECU system and everything was cleared from the FSM perspective. I have a test that I want to conduct on the injectors to make sure that they are opening which would be the following: 1. Pressure the fuel system. 2. With the car off, send a 12v signal to an injector for an extended amount of time, the fuel pressure should lower due to fuel escaping. 3. Remove sparkplug from that cylinder and smell for gas injection. Hopefully this would help me diagnois if my injectors are faulty/clogged/etc. before I purchase a new fuel pump as well. Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted January 27, 2011 Share Posted January 27, 2011 (edited) you are wrong in assuming the fpr will open above 36 psi. as i said the premise is the pump will always deliver more fuel than necessary so something is always bypassing unless you have Huge injectors and running WOT. You are confusing a back pressure regulator which is what the fpr is in engineering terms versus a safety valve which opens to relieve excess pressure then closes when pressure drops. a back pressure regulator opens and closes smoothly and incrementally to maintain a constant pressure on the line being monitored. In this case the fuel ring. Edited January 27, 2011 by roger.svoboda Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted January 27, 2011 Share Posted January 27, 2011 The fuel pump has a safety diverter valve, well,should have a safety valve, but it's supposed to kick in at 90 or so psi. Maybe yours broke. Quote Link to comment Share on other sites More sharing options...
s30red240z Posted January 27, 2011 Share Posted January 27, 2011 (edited) Try with a single injector unrail in your hand, crank the engine, and the injector have to do click click. I fixed similar fail to 2 zx, if the injector test lamp light on, but the signal does not strong enough to open the injector, this is a typical fail in the resistor pack or injectors main relay. Edited January 28, 2011 by s30red240z Quote Link to comment Share on other sites More sharing options...
zsteelman Posted January 27, 2011 Author Share Posted January 27, 2011 To s30red240z: I tested the voltage that I was recieving at the injector harness connectors and was receiving 12volts so I assume that was not an issue. When I test the injectors, shouldnt the click sound the same as it does on the cold start valve? If so that could be my problem because my CSV has a very audible click but the fuel injectors do not make that sound at all. As for the fuel return issue, the FPR only opens when it gets to that point in the psi range, if it never reachs that PSI then it would never open and no fuel will go to the return line as that is the only connection to the return line is through open FPR port, hence my return not getting any flow, correct? Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted January 27, 2011 Share Posted January 27, 2011 not correct read my post and understand what a back pressure regulator does versus a safety valve. which by the way you no got. more fuel bypass lower the fuel pressure. less fuel bypass higher pressure on the rail. the fpr regulates the bypass flow to maintain a constant pressure on the fuel rail Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 27, 2011 Share Posted January 27, 2011 s30red240z has a good point. Maybe you are not getting enough current through the injectors to open them. Or you might not be getting a proper ground through the ECU (same result). Then injectors are powered all the time when the key is On and open when the ECU grounds the circuit. If you have a spare injector, you could plug it in, in place of one on your engine to see if it is opening. s30red240z suggests holding it in your hand because then you'll feel the click as it opens. I recently cleaned my injection harness connections and put newer injector connectors on and now can actually hear the injectors clicking open when the engine is running. Before then, they were barely audible. Your FPR is designed to flow fuel through the rail all of the time. The orifice to the return line gets bigger or smaller to maintain a 36 psi difference between the inside of the manifold and the fuel, but it is always open when there is enoguh pressure from the pump. So if you don't have fuel in the return line, something is wrong. You could pop your CSV out and hit the starter to see if fuel is actually getting in to the fuel rail. Follow your fuel line from the fuel filter outlet through the rail, to the FPR and out to the return line and you'll see how it works. By the way, sucking gas fumes through a shopvac doesn't seem like a good idea. Quote Link to comment Share on other sites More sharing options...
zsteelman Posted January 28, 2011 Author Share Posted January 28, 2011 (edited) Fuel is definately getting into the fuel rail because I initially had a fuel leak at the injector hoses, and now after replacing all hoses I can pressurize the fuel system. The CSV ejects fuel (can see it injecting into the intake via the throttle body). I am really starting to think that the fuel pump or fpr is the problem in this case, mixed with possible bad injector connections because I cannot foresee ALL injectors failing at the same time. time is come and go but I will try and get some more investigation done this weekend. Thank you guys for taking the type to help me figure it out. Edited January 28, 2011 by zsteelman Quote Link to comment Share on other sites More sharing options...
cgsheen Posted January 28, 2011 Share Posted January 28, 2011 How long has it been sitting? Both of the L28ET's I've swapped had "frozen" injectors - probably because they were taken out of service and sat unused. Couldn't get a click out of any of them. Had to "cycle" each injector dozens of times manually to get them opening... Quote Link to comment Share on other sites More sharing options...
zsteelman Posted January 29, 2011 Author Share Posted January 29, 2011 Well I finally got it to start up and idle with alittle bit of throttle. Sounds good, alittle lopey at low idle but revs nicely and sounds good. Getting about 20ish psi of oil pressure at the factory gauge (which I question) but the engine sounds good. It is about 40 degrees here and I have not let the car run long enough to really get warmed up. I ended up going back to the injectors and scrapping the connector pins off with an exacto knife to make sure I get as much contact as possible. So I assume that the injectors were not getting enough current through them to open up. They also may be slightly clogged some which could be the reason the car will not idle without some throttle (I tried adjusting the idle screw which did nothing). I have both injector cleaner and seafoam in the garage, which would you guys recommend for cleaning out the injectors? I had intended to put the seafoam in the oil, intake, and fuel to clean out some of the sitting gunk that may be left over. Thank you guys for all of the recommendataions, and for any of those out there. GET THE FACTORY SERVICE MANUAL! I ran through it and was able to eliminate all of the electrical possibilities and track it down to the fuel problem alone. Quote Link to comment Share on other sites More sharing options...
zsteelman Posted February 8, 2011 Author Share Posted February 8, 2011 Another update for the Z, attached is a video of the car idling, however I have to say that it will not idle at 0 throttle. I have a quarter wedged under the throttle to keep it idling at about 900-1000. It is currently about 40 degrees here so letting the car run for about 10 minutes still didn't get the car up to a high enough temp to get the themostat to open. I still have the cold start valve connected which helps with the cold starts. The odd issue comes to why it will not idle at all without throttle. This makes me think of a possible vacuum leak, however, if I remove the oil filler cap, the car starts to idle alot better than without it. I have tried backing the idle screw all the way out and it makes no difference to the idle. Any advice on what to look for now? As a side note, when the car is running the brake pedal will drop down to the floor pretty easy, yet still comes back up to me. Not sure exactly sure if it is an indicator of another problem. Thanks, Quote Link to comment Share on other sites More sharing options...
peeweetee Posted February 8, 2011 Share Posted February 8, 2011 did you clean the filter screen at the fuel pump intake? Quote Link to comment Share on other sites More sharing options...
zsteelman Posted February 9, 2011 Author Share Posted February 9, 2011 The fuel system is completely refreshed as well as the gas is pumping out of a 5gallon container on the ground not from a rusty tank. I am hoping to pull the PCV valve to check and make sure it isn't getting stuck. I also think that I may be running rich which may be the reason that the car runs better with the oil filler cap off allowing the engine to suck in some unmetered air. I currently have the cold start valve still attached and connected in the car which is injecting fuel due to it being 35 degrees outside. However I have the air regulator removed from the car so it is not providing the extra air that would go along with the extra fuel. Hopefully someone can let me know if my logic is right here on this case. In the middle of a blizzard here in Arkansas right now so going out in the garage doesn't sound too fun. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 9, 2011 Share Posted February 9, 2011 The cold start valve only adds gas when the key is turned to Start. Otherwise it just sits there. It is only for Starting. The Air Regulator doesn't add "extra" air. It just bypasses the throttle body to increase the idle speed without having to open the throttle blade. But the air is still passing through the AFM, therefore is metered. Did you block the hoses, or just connect them together? Without the Air Regulator, the engine will not keep running until it's warmed up. That might explain the need for the quarter. If you can't fix the Air Regulator, you're better off to block the hoses, and use the idle screw yo keep it running, at least for tuning purposes. The return spring on the brake pedal will bring the pedal back up. You either have brake lines full of air or a bad master cylinder, or both. If it's air, you should be able to build some pressure by pumping the pedal. Make sure that your water temperature sensor works and is connected to the right plug. It has the same connector as the thermotime switch. If it's not connected properly and working, the ECU will keep adding gas through longer injection times like it's stone cold. The most effective way to check is at the ECU connector. That way you know that the the sensor and all of the wires are working. There's a table of resistance vs. temperature in the FSM Engine Fuel section. Pick your engine temperature and measure at the sensor's ECU connector pins. If one temperature is correct, odds are everything is working. Your problems are very common to all of the old "ran when parked" EFI Z cars out there. I've gone through the same scenario on two so far. Quote Link to comment Share on other sites More sharing options...
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