I think I know the answer here, but would like some opinions....

My '83 GS runs really well, for the most part...starts easy enough...pulls all the way to redline.
I have one issue, while at idle (let's say at a red light) once I try to "blip" the throttle to get ready to engage the clutch, the engine sort of stumbles? I have to sort of lightly pump the throttle to bring the rev's up. This doesn't happen when the car is cold and the choke is pulled all the way out. I originally thought my car was idling too low (500 rpm) so I raised the idle up to 700....still the same thing.

My guess is the accelerator pump is beginning to fail (or already has) and a carb rebuild is inorder?
What do you think?

 

Accel pump is a real possibility (maybe not the diaphragm, but a gummed up checkball), but so is a clogged primary transition circuit.

Or the accel pump linkage may be out of whack.

 

accel pump was my first thought as well.

 

check everything associated with the acc pump. work the throttle slowly with ur hand and watch how things move. things can be out of adjustment, too much wear in the throttle shaft or linkages.

 

Make sure your basic tune up is good. Timing is good. No vacuum leaks. Idle is at the proper level as is your mixture screw. Then play with the pump shot cam.

I fought this for a long time and found the coils weren't getting full battery/alternator power. Once I remedied that, no more stumble.

 

I just dealt with this, and it was goofy idle settings. I had to turn my idle speed screw in 3 full turns and my idle mixture screw in 2 full turns to get her to idle correctly. No more stumble.

Here is a question: when you sit still in the car for a short period of time (<60 seconds) do your eyes start to burn? If so, your idle settings may be too rich.

 

Thanks Whitey (and everyone else)

But, no, no real symptoms of running overly rich....replaced plugs a couple of months ago and they were very clean...no indication of running rich. (BTW, my car has this problem since I got it over a year ago...it's my dd)

The tune seems pretty good too....timing is spot on, and I don't think I have any vac leaks...will check the Accel pump this weekend....I'll also check out the connection to the coils. Thanks.

 

if you wanna play with the carb, there are a couple of things to check

1. if the idle mixture is way off one way or the other

2. if the idle SPEED screw is off too war one way or the other it can do it too. idle speed is kind of the wrong description, since the placement of the throttle plates controls the idle and transition circuit.

3. the accelerator pump linkage should start moving right when the throttle linkage does