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Hey guys (and gals), I'm the new proud owner of a 1977 280z. I don't know a ton about cars, but I'm mechanically handy and I have downloaded and read through the FSM and the FIB for the car. When I first got the car, it had been sitting for a year and wouldn't run at all. After replacing the fuel pump, it starts and runs, but very very rich. It fouls all 6 spark plugs in short order and idles very rough, occasionally dying. I first suspected the CSV, so I disconnected it with no success, though the engine still started fine so I have left it disconncted. Then I pulled the CSV to see if it was leaking fuel, but it was fine as well. Next I checked the water temperature sensor and air temperature sensor, which reported 2520 ohms and 2260 ohms at the ECU in around 68 degree weather. Finally, I ran through most of the ECU checks in the Fuel Injection Bible and while the air regulator circuit failed, it would result in an overly lean fuel air mixture, right? I rented a fuel pressure gauge, at idle between the fuel filter and the rail it was around 32 PSI, which I know is slightly low. Since it's a new fuel pump, this makes me think that the fuel pressure regulator is suspect. Would a messed up FPR cause a low fuel pressure and make the car run rich? I checked the fuel return line to the tank by blowing in it and after momentary resistance, I could blow through. I also put the fuel pressure gauge between the rail and the fuel return line. There it indicated no pressure. I then pulled the line while the engine was running and very little to no fuel was being returned at idle. I pulled the cover off the AFM, all the contacts look good, the flap moves freely, and the glue blobs all appear untampered with. At idle, the flap moves about 1cm back, though if I finger it to the lean side, the car runs much smoother. I've considered tweaking it a few teeth toward the lean side, but I would rather get to the root of the problem. A few other things I've tried: adjusting the idle screw with no real change, pulled the oil cap while idling and felt vacuum resistance plus it ran worse, visually inspected all vacuum lines and tightened hose clamps, and examined the electrical connections. I'm sure I've tried a few other things and forgotten to write them down, but please suggest any boneheaded thing I may have missed. I feel like my problem is with the FPR, but most of the threads I've read on it say your car will run leaner when the FPR fails. I've also considered replacing my water temp sensor even though it tested fine at room temperature since it seems to be a likely candidate. I know I probably need to check my vacuum pressure next, but I wanted to consult the gurus here before I spend any more money.

My duel SU round top 3 screw runs crappy and is backfiring through the exhaust when you pull your foot off the pedal(deceleration) what does this mean, does it mean it is running rich? Any help would be appreciated. It is also running rough and seems to want to stall. I just adjusted the carbs and float.I set the floats at 9/16 they do not suck full at that point but begin when the float starts to drop, I used the FSM for the carb sync. any ideas ZDUDE1967

Hello everyone, I have a 78 280z 2+2 with a 4 speed. I recently had issues with the engine that made it run rich enough to gas up the oil and it wouldn't run without flooring it basically. I had the AFM adjusted leaner, the cold start disconnected, and had it running well and one day it did this. so we swapped the engine out of my dad's 80 280zx because he wants a SBC in his. I had to move my temp sensor to the thermostat like on the old engine, use my distributor and replace the temp gauge sending unit, along with a few other swaps to configure the cooling and the vacuum to work right. The engine ran GREAT in his car, and we just put his AFM into it with the engine. we couldn't get it to start, so we did a ton of simple checks like plugs, wires, etc. figured out the firing order was wrong on the dist cap and after we got it right it started up and ran rough. we checked the timing and got it running smoother, but the next day we went to start it and now it won't start at all. it gets fairly close but only if the timing is really retarded, and the pops thinks it's loading up with too much fuel. any ideas on why? it's getting to be really annoying sharing 2 vehicles with 3 people when I have my car licensed and it's not running... any help would be greatly appreciated, thanks everyone who takes the time to read my novel thread.

I've got: 1. New Cold Start injector 2. New Plugs/wire 3. New Vacumm hoses all round 4. New Fuel Injectors, new wiring harness/pigtails I'm only getting 11 MPG -tail pipe is black and I can smell gas/fumes while I drive. Thanks for any tips to check next