Hey guys I just joined up because I just bought a my first Z yesterday, I got ahold of it for pretty cheap because barely runs at all due to being running so rich...

So I need some help troubleshooting my fuel problem, I finally got it to fire up today and It idles high (about 2000RPMS) and spit, spudders, and shoots flames when I rev it as well as pours black smoke at any RPM...Im hoping its just the air flow meter but I dont want to order one and it be something else...Any idea of what my problem could be, I know the AFM has been messed with because the side cover is off of it and I can see the internals.

Blocked off the fuel line to the cold start valve this morning and it ran worse

and my fuel pump is wired to a switch so I got it running(still very rough) and I turned the fuel pump off and it ran little smoother until it ran out of gas....

Is your fuel filter there? It sounds insane, but when I got my car the idiot PO bypassed the fuel filter and it ran terribly rich. Got 97 miles on my first tank of gas. Also could be a problem with the fuel pressure regulator? I'm not sure.

Too many variables there for me to even hazard a guess. Fuel pump wired to a switch (why?), AFM 'messed with' (why?). I'd need a lot more information.

1) Verify timing. Pull the valve cover and distributor cap. Manually rotate the engine until the pulley timing mark is showing 0 BTDC. Check that the cam lobes for #1 are making 'rabbit ears' and also check that the rotor on the distributor is pointing to #1.

2) Grab a Factor Service Manual (FSM) for the car from www.carfiche.com. I believe they have one for a 1977 280z. If not, grab one from a close year.

3) Adjust your AFM per the FSM and attempt to set it 'back to stock' if you can.

4) Verify that the cold start valve, thermotime switch, cylinder head temperature sensor (not sure if 1977 uses one)/water temperature sensor (not sure if 1977 uses one - if is either this of the CHTS) are all operating normally.

5) Install a fuel pressure gauge inline before the fuel pressure regulator. Verify that the fuel pressure is within the range specified by the FSM.

6) Verify that your injectors are clicking (open and closing) by putting a metal rod or screw driver against the injector and your ear at the other end.

This is just a quick start off the top of my head.

I did notice the other day that the guy had the fuel filter run through the return line?? so I fixed that and its still the same... Ive checked all the injectors for clicking...And another thing It runs even worse when it warms up, It will rev just fine when cold but when its warm I can forget about it

So basically when its cold its fills up my driveway with smoke but its still kinda sorta driveable, but when it warms up it fills the whole neighborhood with smoke

Umm... well I suppose the coolant temp sensor could be another place to start...

(In case you haven't guessed, this game is HARD... you know the figure out what's wrong with your car game)

You could try messing around with the AFM while the car is on, don't adjust it, just press on the flap to open it more and/or close it more and see if going either way helps or clears the smoke.

There's always the remote possibility of a bad ECU too.

With things being that rich though I suspect it's something more mechanical than electrical/sensor related, but the components involved that I'm thinking of have already been mentioned.

maybe it could be, that somehow your afm is out of adjustment, and the spring tension is too loose. I found this out with mine, it was so loose it would hardly idle. It ended up being blown loose because the spring clip that holds the gear in place, got shook when the car was running to lean (from a twisted fuel line) and backfired into the AFM.

What it sounds like is that you have a car that has been heavily screwed with by previous owner(s) and would be impossible to diagnose by asking questions on a car site. You'll get some good advice like ktm's post #5 but basically it's a guessing game. The best thing you can do is, like ktm said, get a FSM. Learn how the different systems work, study the charts and diagrams and compare your car to it and try to correct what is wrong. I doubt if you'll find some kind of magical answer here.

I was thinking the same thing Stephen. You need methodically go through the systems one by one and verify that they are operating per the factory specifications. These cars are quite simple to work on, even with their archaic EFI.

Do not fall into the trap of just throwing parts at the car and hoping one of them works.

I would check the fuel pressure regulator. When they go bad, they usually go very rich due to to high of pressure. With the cars age, these are starting to go bad more frequently. To bad I'm not headed to Knoxville this Christmas, I drive right by there on my way from Tampa. I even have a factory EFI analyzer.

Jim

I would check the fuel pressure regulator. When they go bad, they usually go very rich due to to high of pressure. With the cars age, these are starting to go bad more frequently. To bad I'm not headed to Knoxville this Christmas, I drive right by there on my way from Tampa. I even have a factory EFI analyzer.

Jim

Thanks for all the the advise fellas, I woulda bought a FPR already but if that doesnt fix it then it would be a quick $50 down the the drain...Anyhow Im selling the car for $650 and I have a guy interested down here that knows way more about Z's than I could ever know, So I think Im going to send it down the road with him