I had a buddy of mine take a look at my 83 z28 yesterday becuase It has been running very badley. The car would hesitate until about 15 mph and then just take off. We took the air cleaner off and took a look at the carb ( regular stock q-jet) and he said when I hit it real fast it was injecting way to much fuel into the carb and almost choking itself out. I have been reading on the forums and it looks like my problem is my accelerator pump. Is there a way to adjust these or might I just have a bad pump. I am planning on rebuilding the carb this weekend just wanted to figure out my problem before. Any input is appreciated.......

 

Is this hesitation under all conditions, or only going WOT from a stop?

 

It seems to just be WOT from a stop at a light or something. If I ease on the gas it will go pretty good but hammer on it and it falls on its face. The car does not feel like it is going to die or anything but just no power at all it seems until I hit that 15mph mark and then she takes off.....

 

If the car is mostly stock it is most likely not your carb that's the problem. It is more likely timing or some other operating condition of the engine itself. You can not easily adjust a Q jet accelerator pump -- you can solder and drill the pump shooter orifice inside the carb with tiny numbered drills, but that is probably way beyond what you need to do here. Usually even with modified setups the Qjet pump shot is close enough. An engine not taking fuel is probably retarded timing. You have to set the timing on these engines w/ the set timing wire disconnected on the dist, and then use the appropriate base timing setting (6 BTDC for an 83 Z28)

 

Well, I agree that you need to make sure the ignition is up to snuff.

But, it sounds like classic "Quadra-bog" - where the secondary air valve opens too quickly. Go to the tech article linked on the thirdgen.org homepage (also linked in the "read first" sticky above) about adjusting the air valve tension. Also understand that the choke pull-off plays a part in this, and if it is leaking, you'll get the same thing - bog when going to WOT.

 

What would be causing to much fuel to shoot into the carb...

 

That's not happening.

 

Also when I am at an idle stop I only Idle at like 4,000 rpm most of the time sometimes 5 does that seem to low....

 

you mean 400 or 500 rpm? It sounds like you should take this car to someone who works with carbureted vehicles. Seriously.

 

yeah sorry 400-500

 

500 RPM idle in drive is the stock factory setting.

 

i had the same problem..it was the seconary air valve...and five7kid showed me the article and it works perfect now

 

haha, that's a good sig line xgtharo

But yea, "quadrabog", ie, too quickly opening secondary air valve is the single most common form of a bog.

Besides, if I figured you were getting too much fuel from the pumpshot, i'd try to lean out the primaries instead. It's a little strange for the pumpshot to all of a sudden be too big. Anyway, I really doubt the pumpshot is the problem. Try setting up the A/V tension to 3/4 turn, and make sure your vacuum break doesn't leak.

 

Thanks for all the help guys I got the AV tension set to 0 and i worked with my idle screws on my carb a bit and the car seems to be running alot better now...

 

0? That can cause a decent bog, you want a bit of tension there.

Idle screwS? Plural? Well hey, can't argue, if it runs good enough for you I guess you're done.