[kelstar]

I noticed a ridiculous lack in power... pulled off the air cleaner... put my hand over the front carb and the car about died, put my hand over the rear carb... nothing. If I hold my hand over the rear carb and work the throttle, I can feel it pulling a little bit but nowhere near like it should be... I'm new to this whole dual carb thing... any ideas what's going on here? Oh, yeah... as it is not sucking in, the fuel is just kinda sitting there in the carb. I don't know what difference that makes, but I guess the more info the better.

Thanks!
Shayne
74 260Zeeeeeeeeee

 

[kelstar]

By the way - these are the earlier dome type su's... not the flat tops.

 

[bumble zee]

might want to check your bowl to see if that foat is letting fuel in... and the check to see if the piston in the dome moves freely.

 

[kelstar]

ok, I just went out to tinker with it a little more. If I work the linkage so that just the rear carb (the one I'm having problems with) is being used, it revs up slowly and stops revving when it gets up a little bit. I don't know what rpm it stops at as I cant see the tach from the engine compartment, but I'd have to guess it stops at about 3000 or 3500. If I work the linkage for just the front carb, it revvs normally... I'm frekin confused.


Shayne

 

[kelstar]

the piston moves normally. I haven't checked the float yet, but even if no fuel was getting in there, it should still suck, right?


Shayne

 

[Andrew240Z]

check to see if you have compression on all of your cylinders that are fed by the back carb, (4,5,and 6) Mine had these exact symptoms, and it was a bent valve. if you have compression, then it's probably the carb float problem.
andrew
73 240z
82 zx

 

[jazzbug8]

Sounds like your rear carb is running to lean. Warm your engine to operating temp, disconnect the rear choke. If you lift the carb piston and the engine stumbles, that carb is lean, if RPM speed increases it is too rich. In your case, try backing out the mixture adjustment wheel on the bottem of the carb one flat at a time until the engine RPM doesnt change when you lift the piston, or it rises very slowly and returns to and even speed. You should also get a Unisyn tool or similar device to properly set the idle speeds for each carb.

 

[kelstar]

hmmm...

Ooookk...I checked the float, just for the sake of checking it, though I have no idea how that could possibly keep the intake from sucking air through, and it checked out fine. The air/fuel mix is right on, and the compression is good. I'm just saying, I really think it's virtually impossible for it to be the actual carb itself. Even if there were no fuel to the carb at all, there should still be suction if you hold your hand over the intake... Oh, well... I guess I'm back to replacing a bunch of things and seeing how they check out until I finally get the right part... of course then something else will go and I'll have to do it again... I should have a brand new Z in a year or two!!


Shayne

 

[joeytekno]

Re: hmmm...

youre right about having a brand new z in a year or so if you have luck half as bad as mine.. your first step should be a ztherapy carb rebuild kit.. its 100 bucks but its worth alot more once you feel confident your carbs are dead on.. youre probably missing alot of power and also wasting gas.. go to ztherapy.com.. immediately