popping through quadrajet what causes this?

[Christopher R.]

I have a 1972 Corvette L48, automatic. When I took the car out for the first time for the season as i live in the northeast, the car starts and idles up on the choke and comes down once warm as it should. however, when i started to drive down the road, the car began to bog and pop through the quadrajet - never had that happen before. If you accelerate above a certain point, seems to go away but comes back again until the engine is really warmed up.

the car ran perfectly last year, car was stored properly with stabilizer so any ideas? I have seen posts about timing and adjusting the needles for lean/richness. So i will make a run at this weekend troubleshooting some common areas. thanks again.

[Edward J.]

Re: popping through quadrajet what causes this?

Chris, have checked to see if the accelerator pump is working, if you look down the throat of carb. You should see a steady shot of gas when you move the accelerator, if this does not work you can create a lean condition causing the backfire.

[Mark E.]

Re: popping through quadrajet what causes this?

If it ran perfectly before storage, let's begin with what the cause is probably NOT: it's probably not a timing issue and it's probably not a carb tuning issue (e.g. different jets, rods needed or air door adjustment). These things don't get worse during storage.

It could be many things; I suggest starting with the usual suspects that happen during storage and are easy to check: bad fuel, vacuum leak (maybe a vacuum hose dried out a bit more and is loose, or the carb/manifold gasket dried out and became loose), loose spark plug cable, dirt/trash in the carburetor and/or filter, poor fuel pressure (likely due to a dried out fuel pump diaphragm). Double check the choke to make sure the rod is connected on both ends, it does not bind and it stays open when hot.

[Duke W.]

Re: popping through quadrajet what causes this?

...agree with the above.

When was the last time the fuel filter was changed?

Duke