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260z carb issues


Stik3v1n

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I've been helping my friend figure out what is going on with this early 260z. He got 2 new ztherapy carbs and it runs and idles fine but once you put it in drive, the car won't move. We were able to get it to move like 2 inches and that was with the gas pedal to the floor..lol. I got tired of messing with it and went home. He thinks maybe he has a bad EGR. Hopefully someone can chime in cause I don't know much about it since mine has a swap before I even drove mine.

 

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Linkage connected. The rpm did not increase with steppimg on the gas. However, at idle when you blip the throttle from the linkage it revs up like normal.He checked the vaccum at primary vacuum port by the manifold and it around 15 psi at idle. Told him to check timing.

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Have someone inside the car press the gas pedal to the floor, while you watch the throttle movement at the carbs. Then compare it to the amount it moved when you blipped the throttle manually. If it moves less (or not at all) then there's something wrong with the throttle linkage. If it moves the same, then you can move on to engine settings like timing, etc.

 

Given your situation it doesn't make sense to start messing with the tune until you've confirmed the throttle linkage is functioning properly. Just my thought

Edited by pkz
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New carb installation?  Check for Vacuum leaks! 

Pull air cleaner(s) and confirm Throttle plate movement, as well as vacuum piston is operating. 

Check that both carb float bowls have fuel.

Check ignition firing order, and timing.

 

If it ran before you pulled the carbs off, it will run now once you find the (most likely) very basic problem.

 

On the 260z's the casting plugs on the EGR portion of the manifold tend to rot out creating a massive vacuum leak.  The casting plug iirc is on the backside of the manifold, between the manifold and the valve cover so they are hard to see/find.  Casting plugs can be found cheap at your local napa. 

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Rejracer, I haven't checked for the plugs behind the manifold. We did test fuel pressure and we got 4.5psi at the supply line. So we connect the fuel hose to the fuel rail and it wasn't making any pressure. We took it off and blew the lines out. Sprayed some carb cleaner in there and blew it out. Connected back up and still no pressure. When I say no pressure I mean less than 1psi.

 

So we ran a rubber fuel hose teed off to both carbs to get the proper fuel pressure. This maybe a noob question, mechanic pump is not blocked off and I think it should. The pump is on there but lines not plugged. Should be plugged or blocked off so there's no vaccum loss or am I wrong?

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