Choke is doing the opposite...any thoughts

[mally002]

A few weeks ago I posted about my vapor lock issue and mentioned the choke problem as well, any other thoughts on the choke....the vapor lock hasn't been an issue, but of course the temps are back down in the 80's again but this stupid choke is driving me crazy.

It's a stock 1971 240Z with no mods.

When first starting the car I pull the choke all the way back and the car starts right up, no issues. After driving for awhile everytime I push the choke in the car starts "bucking" and "sputtering" pull back on the choke and it runs just fine.

Of course with the choke pulled back, everytime I come to a stop or slow down the engine idle is pretty high, but I can't push in the choke because then the car runs like CRAPOLA.......:sick: Also the gas smell is much more extreme keeping the choke fully engaged.

I checked the cables, and everything is how it should be. Also on the air filter the selector switch is on Summer....but would that really matter?

Do my carbs need to be rebuilt?

Also....FYI I did add a new fuel filter yesterday....no help.

[MikeW]

I'd start with the basics and go from there. Before even messing with the carbs you want to make sure everything is in tune: timing, points gap, plugs, plug gaps, cap, rotor, etc. It's normal to need the choke on until the engine warms up so I'm not sure how long "awhile" is.

If you do have to start messing with the carbs I'd try adjusting them before thinking about a rebuild. Get the Ztherapy video or find some of the great directions available on this site. It may be that the mixture is off on one or both carbs. You said you already checked the choke cables but I'd verify that both are moving the same amount and using the full length of travel.

[beandip]

At first start up pull the choke to full on. As soon as the engine fires you can move the choke lever forward to maybe 50% , depending on the temp out side. Also when you first pull away from a stop if the engine is still cold it might , as you said buck. This is simply because the engine is not up to driving temp. So just add some more choke until it drives correctly. As the engine continues to warm up to the proper temp. you can move the choke lever forward. It takes about 10 min. for the engine to be up to temp. Even on a warm day. I think from your description that you simply have been using too much choke and then too little as the engine is still not up to temp. The temp gage will show the water is warming a long time before the engine is actually warmed to driving temp. Hope this helps . Gary:rambo: Some times drivers coming from computerized injected cars have this same problem until they become accustomed to this old way of doing things.

[xray]

Hi Randy,

If it runs like crapola without the choke, and fine with it, do you think the fuel is set too lean? Or possibly a vacuum leak?

So it only happens after 10-15 minutes of driving? Are you driving the whole time with the choke on? Your temp gauge is coming up within 5-10 minutes? Thermostat is working correctly (maybe it's stuck open and never gets to operating temp...)?

Good luck!

[mally002]

Hey guys,

Thanks for the info....I can be driving the car for 30-45 minutes and still have the same problem. Last night my wife and I took the Z to a cook out near the tail of the Dragon...easily 45 minutes one way and at various times I would try and ease the choke in and everytime it would run rough and "buck".......pull back on the choke and runs normal.

I'm going to try and tinker with it again today.....so if anyone has any suggestions let me know.