Truffles

okay, ill try messing with it. I found a guy that parts the z's somewhat near me, so ill see if I can work something out. thanks for all of the help. I will update once I fix the issue.

so I ran through each wire for the thermotime, coolant sensor, air regulator, and the cold start valve. ran a 12v wire to each wire on the ECU plug, one at a time and made sure each one is hooked up to the proper place. started it up and same problem, it fires immediately, idles at 500 RPM, back fires, bogs and dies. If you touch the throttle at all it dies immediately. Exhaust reeks of fuel, and plugs are soaked. any ideas of where to go from here? I'm seriously considering biting the bullet and just buying the FAST injection kit. but I doubt I could sell everything I have put into it trying to make this system work to make up at least some of the cost.

Awesome, I will run through that tomorrow when I am able to work on it after work. I will update if it solves it or not, thank you so much for the help, it is appreciated.

got home from work today and pulled the plugs and did that test with all of the injectors unplugged to see if they were stuck open, and luckily they are not. bitter sweet though, because that means I still haven't found my problem, but at least I don't have to buy another set of injectors. Your right, because it is not my injectors, pressure drain cant be what is causing my flooding. I had my light tester right there so I hooked it up to a good ground, then attached it to one of the bullet connectors to the coolant sensor at a time. no power when key is on or during cranking for both wires. Then I did the same for the bullet connectors for the thermotime switch. Both of those had power at cranking. So that's a problem right?. Each sensor should have a power supply and then a signal return wire back to the ECU. The sensors both work by grounding themselves relative to the coolant temp. that's what I got from my FSM anyway. Am I right about that? When I originally installed the motor, both of the wires that get power at cranking are in the same sheathing and the ones that don't get any power are in their own sheathing. then both lead into the engine harness. all 4 wires are white with no lines or marks, the ones that don't get power had a small piece of red tape around them near the bullet connectors, and so did the bullet connectors going to the coolant sensor, so naturally I hooked those up and the other ones didn't have read tape, so I hooked those up to the thermotime which also didn't have red tape, never tested them, just assumed that's how they marked it. so now I have to figure out which positive and which return wire corresponds to the right pin in the ECU plug and hook them up proper correct? In the picture you can see what I'm talking about, but when I took the photo I had swapped them trying i figure out my problem so originally I had the opposite from in the picture.

Just went and did that, with all injectors unplugged, the pressure dose still drain just as fast and the regulator vacuum line is dry the whole time. so either check valve (which wouldn't explain the amount of gas in the cylinders) or the injectors are stuck, because there isn't anywhere else for the fuel to go except on the ground, which isn't happening. so I think tomorrow evening will be pull the plugs, and I will do the same test with the pump, I can look in to the chamber to see if it is in fact just draining into the cylinders. because the oil is more then likely contaminated already anyway. If it doesn't then it has to be the check valve correct? sure hope I can return these injectors for being faulty! if not, then its definitely a loss I just have to take. about the oil, yep I absolutely am going to change it once I get this problem fixed👍

thank you so much! I just went out and unplugged the ECU, turned the key to "on", fuel pump didn't turn on. so I pushed the cog on the AMF a little and it kicked on. ( I'm sure in the attempts to fix it by adjusting the AMF I put it out of adjustment) When the pump kicked on I seen the fuel pressure jump up, and then after I let off it fell quickly. so from your first reply that would mean I have a short somewhere in the engine harness in between the injectors and the ECU correct?

i just finished my full rebuild on my 75 280z 2+2, picked up a F54 block with flat top piston and P79 head. i did a full basic rebuild. bearings, rings, lapped valves and all of that. swapped in a 5 speed, replaced all of the bushing with poly ones, new fluid in the trans, and diff. got it all together and here we are.. Initially it ran, but horribly rich to the point of if you try to rev it up at all it would start sputtering, back fire VERY loud, and then when you let off it would stumble and die, then trying to start it back up it wont crank over, pulled the plugs and sure enough, fuel poured out of the cylinders, disconnected the injectors, cranked it over to shoot out as much as I could, then I let it sit for a couple hours after cleaning the plugs. came back, put the plugs in, and would do the same thing. I disconnected and capped off the cold start valve, same result. replaced all injectors with new ones, same result. replaced the Thermotime switch, and both coolant sensors. still same thing. I double check my new vacuum lines with soapy water, no leaks. tried adjusting the TPS, no difference. popped open the AFM, tried adjusting the three adjustments one at a time, even with BIG changes to the cog preload and/or the center piece adjustment would make small improvements but still wouldn't idle alone. if I hold the cog very slightly forward while still making contact with the copper idle tab, it would idle, but only at 500RPM and every other second or so it would start to stutter, drop rpm and then catch back up and smoothen out. but if you even breath on the throttle it dies immediately. hooked up fuel pressure gauge where the cold start valve hooks up to the fuel rail. it says it has zero fuel pressure while idling, but after it dies, it jumps up to about 35 for a second and then steadily drops to zero in about 5 or 6 seconds. I try to start it up again, and it wont crank, pull the plugs and the cylinders are full of fuel. Pump it out, clean plugs and wait a hour or two and try again.. i have no idea what could be causing the new injectors to stay wide open the whole time the key is on.. replaced or tested: fuel pump new fuel filters used fuel pressure regulator reman. fuel injectors new coil, cap, rotor, plug wires and plugs. on my second set of iridium plugs all injectors getting signal new thermotime, new both coolant sensor and sender cleaned my grounds completely to bare metal on both sides on all. HELP!

great, I will check it out, thank you for the help.

Yes factory fuel injection, but cool I will search around, every time I try to search on this site it tells me it's unable to load for some reason, even on my computer too

Hello, I am new to the forum and was hoping to find some advice on building a head to a stock freshly built F-54 block with flat top Pistons. The motor is in and running currently after just being fully rebuilt to stock specs.I am wanting to experiment and build a head for it in spare time that will bump up performance a bit or just make it a little more fun to drive. I would like a bit more torque and possibly a little more aggressive rumble. Just seeing what my limits and best option will be. And trying to gain some knowledge about these valve trains.