rcb280z

Zed Head, my gauge is mounted after the fuel filter, and before the hard line. I thought about it getting hot and figured this was a good spot. Thanks for the link. Lots of good info there. Oh, I ordered the "dry" fuel pressure gauge. If this one shows inconsistant readings then I will replace fuel pump. FPR is new so it would have to be the pump then. Fastwomen, when you explain it like that it makes sense for a car with a lean condition. I'm still confused, unless I'm missing something, how this will help an already rich condition. as post #129 explains, I'm already rich with 1.8-2.5% CO's. And high Hydro Carbons. I wish the potentiometer was my answer, unless like I said, Am I missing something? Maybe so. My brain is scrambled eggs right now.

Blue, I changed out the FPR last weekend with a brand new one. The vacuum line is new as well. I think, not 100% sure, the fuel pressure is varying due to faulty in line fuel pressure gauge. I will purchase a new gauge and if that one shows varying pressure then I will replace the fuel pump. The one that is on the car now is an aftermarket one. I believe it is the Walbro one. Can't remember exactly, it's been about 10 years. Maybe I should find a stock one and replace it with that. I'm grasping at straws now. But that just means there is still hope. Maybe I should install new injectors? Thanks Blue. Have a great day.

Fastwomen, I have noticed my fuel pressure gauge doesn't give correct readings all the time. Right now it is at 28 psi. So go figure. To adding resistance to the CTS circuit the answer would be no. Not sure I understand it completely. I have read your thread about it but when it comes to electrical I am lost...embarrased to say. Don't get me wrong here, Iwant to try it. Guess I need to read it again. BTW thanks for the input. It's nice to know that everyone has hung in there with me so far. Blue, I just ran the procedure you suggested. Couldn't wait til the weekend. Ran jumper cables from our altima and sad to say there was no difference. I was hoping it would be something simple. Nothing makes sense! All sensors test good! Dangit! What the heck!

Then I think we are good as far as charging volts go. I will measure volts before starting also. Thanks Blue. At least I have something else to look at now. Bob

Blue, in your experience, what should the volts be while the car is running? Shouldn't I get around 14.5 volts at the battery at idle? I remember looking at that some time ago and wondering why I didn't have that. IIRC it was about 13.25. I will look at this as well. I know the Z requires a certain amount of volts for the EFI to function right. For the life of me I don't know why I haven't looked into this more! Probably will get a chance to try your test Saturday morning. Will post results that day.

OK, I started this thread with a fuel pump safety cut off issue....fixed that. I've owned this car for years and didn't even realize this issue until another member had posted the problem with his Z! PO had hacked into harness under passenger seat bullet connector and ran a jumper to the fuse panel! I disconnected the jumper and things were fine. The safety cut off in the AFM is working again. Now I am chasing a cold start issue after sitting for many hours. The TTS, CTS, AFM, and TPS are showing correct resistance...verified by other members here. Oh and checked these at the ECU connector as well. Also tested AAR thoroughly! If I lean out the AFM some the AAR works perfect. Cold start, the idle jumps right to around 1300 rpm until it warms up with a lean adjustment. But when warm it runs too lean. Have performed Blue's AFM calibration and I don't notice a change. I say it's lean because it pops a little through the AFM and it sounds like it has an intermittent misfire also out the exhaust. If I richen the AFM a little (while engine is warm) it smooths out and runs good and no misfire. This is what the numbers were as soon as I put it on the dyno, lucked out that day, he was slow. HC-263 (too high), CO-1.8 (max-0.5), CO2-13.0,? NO-335?, O2-1.3, MPH-15.3, LOAD-134.3? This is the 15 mph test. Here is the 25 mph test results. HC-152 (ok), CO-2.5 (max-0.5!), CO2-13.3, NO-130, O2-0.3, MPH-25.3, load-74.6. So as you can see it wouldn't pass smog if I had to smog it right now....in 4 months I will. Other things I have done: new cat. converter, new fuel filter, had injectors cleaned on car, checked for vacuum leaks. Pulling 18.5" of vacuum and if I turn idle screw lowering idle it stalls out so as far as I'm concerned there is no leak. Even when I pull a vacuum line to hook up my vacuum gauge it nearly stalls before I can hook it up. Timing is 10-11 deg BTDC now. Everything is stock except for the air filter and header. Was running Chevron 91 but now run 87. Oh I also replaced the FPR thinking that was the reason the pressure bleeds off over night but was wrong. It still bleeds off but I am ok with that. Fuel pressure is 32 at idle and jumps to, looks like, 40 when I throttle it. Someone here mentioned the possibility of air in the fuel lines. Haven't checked that yet. Oh, all the connectors except the AFM and TPS have been replaced. Everything I have mentioned above that was replaced has happened over the past 1 1/2 years. Last mileage check was 21 on the highway babying the car. If I lean it out to CA smog requirements it runs like crap! I have tapped on the ECU looking for a loose solder joint, no change. I really thought I was going to find it was running too lean but with the numbers above I'm still confused. I also pulled the CSV harness thinking maybe it is injecting too much fuel and that's not the case. Static fuel pressure test was at about 46 psi. I think I have covered everything. Any thoughts? Anyone?

Blue, do all the S30's have this zerk fitting on the rack? I don't think I have ever greased mine. I wouldn't even begin to know how much grease either. Guess I could check the FSM also.

I started the car this morning with the CSV disconnected and still the same result (unstable idle). It did take just a little longer (couple cranks) to start without the CSV connected. So I know it works. I think my next step will be to remove CSV entirely and plug the supply line, also the mounting hole in intake and start it up tomorrow morning. Maybe it leaks while the car is running.

Start looking for anything that would alert you to the PO hacking into the engine room harness and EFI harness. And report here what you find. I know it sounds weird but, there are a lot of people installing upgraded headlight and parking light harnesses. Do you have lights without the key in the ignition? Turn your lights on before sticking the key in the ignition. See if you have dash lights, headlights, parking lights, etc. Just trying to find a starting point here. Very strange it is. No oil pressure is a concern. You have a 77 so there should be one wire connected to the oil pressure sending unit on the side of the block. Check that it is connected. Maybe the gauge is not working. If you can keep it running long enough you can slowly remove the oil fill cap and see if there is oil slinging around. This way you'll know if you have oil pressure. You are going to need a detailed wiring diagram.

Ok, cool. I will check back. Thanks

Any special instructions grantf for installing the door to fender seal? Did you have to cut it?

True, I did say that and I should do that. Thanks for reminding me. It is unplugged now. If that doesn't improve things then the next step will be to remove it (CSV) and cap the fuel line. Maybe it's leaking.

I got mine off e-bay

Ok here is an update: Started the car this morning and like always she has the unstable idle. So I started turning the bypass screw CCW (leaner) and at 3 full turns she picks right up smooths out and starts idling around 1200-1300 rpm. So like I suspected she is too rich on start up. But after she warms up she runs like crap....too lean. I can't find a happy medium with this car. Oh, and there is 328 ohms at the CTS after warm up. So that is good. ??

I was able to stall it out running the idle set screw in.

Has to be a scary ride!

I had a similar problem a few years back in my 77. I bought new a regulator, and a reman alt from Autozone. Tested the charging system after installing these parts and was over charging! Long story short, after 2 days of trouble shooting and replacing the regulator again, I went to Napa and bought another regulator. It cost more than the 2 together I bought from Autozone but it worked! So sometimes even "new" parts are bad. But yes, definitely the voltage regulator.

Do you have strick smog laws out there in Ohio? We do here in CA. 0.5% CO at idle and part throttle. That is really lean for my Z. And it is stock.

My thoughts also zKars.

It's what you are willing to pay for parts not produced any more. I just hope I don't HAVE the need for anything any time soon!

I will check with my Z mechanic buddy today and post what I find. Thanks TomoHawk. How is your EFI system performing? Mine suck's right now!

Just look them over carefully. You know what to look for....you own an early S30. Either one will probably need work. I have a 77 280 and wish I could afford an early 240. By the time I'm able to buy one they will probably be unreachable financially for me.

Would like to see pics of the same W/S pieces on a 280 door. Same view and angle. The 280 window frame is different from the earlier 240 and 260 Z's

Zed Head, that's a good test to run. I will try that next. As for the hose's for the AAR, they are new. All emissions and vacuum lines for that matter are new. If you have a moment will you look through this thread. There are actually a couple things going on and they have become a PITA. Thanks for your time.

I don't think anyone believes the AAR "affects" mixture ratio. It just adds more air to compensate for the richer condition at "cold" start up. At this point I wish there were someone out there that had the same problem and fixed it.