Hopefully this sounds familiar to someone...

[SavannahZ]

Hey all,

My car is hesitating under low rpm acceleration(under 3000). All tune-up parts in good condition, valves, spark, fuel. What is happening is that the car hesitates and then goes normally when the rpms are higher. The really odd thing, is that it will do this all over town but after I come off the interstate after going a constant high speed the problem dissapears and the car runs great.

I was thinking that maybe air was getting into the fuel line somewhere? Is that possible without fuel coming out?

Maybe it's in the carbs? The float lines are plyable and the choke is in with the adjustments just where I want them.

Just wondering if somebody has experienced anything similiar to this before to point me in the right direction.

Thanks,

Jonathan

[MikeW]

I wonder if it's choke related? It may have nothing to do with running on the highway but rather just the fact that the engine gets fully warmed up.

[beandip]

I doubt the air in the line idea . Have you checked the spark plugs after the low RPM driving that you were referring to ? It could be that you could have a weak spark plug or a plug wire that is starting to fail. At freeway speeds it clears itself out but at the lower RPMs starts loading up. Make sure the chokes are not hanging up and are in good ajustment. On a side note , use some anti-seize on the spark plug threads . When removing a spark plug from a warmed up engine with a aluminum head you can damage the threads in the head. The anti- seiz will eliminate the possability . The problem you describe dosent sound like Carbs , other than choke . I think you are looking at a ignition weakness. Are you running points or electronic ignition ? You dont show what year Z this is .

[e_racer1999]

me thinks: maladjusted choke or dizzy... my grey car had that problem, replaced the dizzy and synched the carbs.... voila!

[EScanlon]

This is just a WAG, but have you checked the oil in the S.U.'s?

Enrique

[zztom]

Have you tried the old Carb-Clean spray on the throttle shaft trick? You might be sucking air. The engine should stumble if the carbclean is getting through the shafts. When I had my old carbs on, I thiught I had them balanced pretty good. The only problem was that they were running rich. After spraying the rear shaft, the engine cut out immediately. ZTHERAPY to the rescue !!!

[Brett240]

sounds like its running rich. plugs black after city driving. try winding some fuel out of the carbs. it would be ok highway crusing becouse the underbonnet temps are down and your air is denser, giving i leaner mixture.

[Zedrally]

This is just a WAG, but have you checked the oil in the S.U.'s?

Enrique

WAG ?

I agree with the oil.

Easy to check and easy to fix...

[Bambikiller240]

"Wild A$$ Guess"

[SavannahZ]

All sound like really good ideas. I have to work tomorrow and will go through the list tomorrow evening.

Thanks!!

[e_racer1999]

sounds like its running rich. plugs black after city driving. try winding some fuel out of the carbs. it would be ok highway crusing becouse the underbonnet temps are down and your air is denser, giving i leaner mixture.

i found the opposite to be true in my situation....