280z stalling issue (I've tried the search feature!)

[HybridzNJ]

So I've tried searching several z forums for this exact issue as well as asked a few mechanics I know to help and have had no success solving my problem... 

My car is a 1975 280z, it has a 1972 240z head and a 1982 280zx block. Dual su carburetors and electronic ignition that I beilive was sourced from another 280zx by the previous owner. The car ran fine for the first year I owned it.

My issue is that the car will start and idle with no issues but after driving for half a minute or so the car wil stop accelerating and wont respond to the throttle. It then will bogg down, my tach will drop and the car will stall out. Sometimes I can keep it going other times I can't and sometimes it will turn back over, other times I have to push it home. When it does this there is a distinct change in the sound of the engine where the tone of the car drops to a low droning sound before it cuts out. 

 

So far I've replaced the coil, alternator, starter, ballast resistor, fuel filter, fuel lines, cleaned the tank, rebuilt the cabuerators, changed the cap and rotor as well as the wires plugs and the battery. 

If there was a good z shop or mechanic near me I would happily pay to have it fixed but I've been unable to find a shop anywhere near toms river nj that is willing to take on the car (and if anyone knows of one please let me know)

 

Anything you guys can tell me is greatly appreciated, I really want her back on the road! Also if there's anymore information about the car that could help let me know and I will post it. Thanks in advance!

[Mark Maras]

 Presumably you're using the choke when you start it. Does changing the choke setting, (plus or minus) have any affect when it starts to run lousy? Did any of the repairs, especially the carb rebuilds, make ANY difference, good or bad? What color are the plugs?

[HybridzNJ]

I am using the choke and no it doesn't seem to change anything if when the problem happens. The repairs did make it idle better (initially sounded like I had a misfire which is gone now). And the plugs are usually a little wet. 

[Mark Maras]

 Does the engine rev freely when not under a load?

[Redwing]

14 hours ago, Mark Maras said:

 Does the engine rev freely when not under a load?

Mark discuss the ECU with him.  Sounds ominously similar to my RedBird.  Maybe he can borrow one to check it out.

Jai

[S30Driver]

He is not running fuel injection Jai, has SU carbs installed so there is no ecu to worry about.

Does the car have strong spark when it dies, does not start, and you can crank it?

[HybridzNJ]

It does have good spark when this happens.

[Mark Maras]

 Too much fuel can be caused from excessive fuel pressure, floats set too high, sticking floats, stuck needle and seat or crud in it holding it open, for openers. Two other things, when the choke is in the off position, reach under the carbs and push up on the nozzles. They can stick down (more choke) even when the handle is pushed forward and be sure that the choke cables are adjusted at the carbs to be sure the nozzles are all the way up (up being resting against the mixture nut which is about 2 1/2 turns down) when the choke is off.

 When the suction chambers and pistons are removed, you can look down and see the top of the nozzle. Set at 2 1/2 turns down, the fuel level should be about 1/16" below the top of the nozzle.

[siteunseen]

Yes! I bought a 240 that had 3/16" from the float bowls to the nozzles where the molded fuel hose should be. He had a zip tie to make the bend but was actually binding up the nozzles dropping action. Big mess!

I haven't read the entire thread but are your valves in spec? If they get way off weird things happen that you chase to end up being the valve adjustment.

[HybridzNJ]

Alright I definitely plan to take another look at the carbuerators. Taking the car to a buddy of mines garage this weekend to knock some things off this list. I will let you all know how i make out and thanks again!