Piston wont move up and down in SU

[Matsdat]

Hi guys, i have just removed my twin su's from the L24. I then installed the SU's in the exact reverse procedure of taking them off (i think). The pistons in the SU's dont move up and down now. I can lift them with my finger quite easily, but they just fall back down. When i start the engine, it just revs higher and higher and there is no throttle response. Does anyone have any ideas how to fix? Im thinking it is something simple but cant seem to find it. Thanks for your help.

[280zjoel]

i had that problem on my 260z before, what i did not notice was that i put the throttle linkage wrong so it left the card open at full throttle. i would check the linkage first. hope that helps

[evildky]

kinda sounds like a rather large vacume leak, was the car running fine before? why did you remove the carbs? you put the same carbs back on? the throttle shaft bushings can wear out and leak as well

[hughdogz]

You might have set the choke cables too tight so that it has the butterfly valves cracked open too much.

 

The pistons are supposed to fall back down...if the pistons are really stuck you might have a bent needle or more likely the tops aren't centered. Try tightening the tops after ensuring that the piston moves up and down freely.

 

You should also add a little bit of ATF so the dampers have some juice. You don't want to fill the tubes all the way up, or else the fluid will just leak out.