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78 L48 Slight hesitation



Purchased this 78 (27,000 mi) from California in late November, I live in Oklahoma City and haven't driven it much do to poor weather. On the few occassions I have driven there is slight hesitation (not stalling) when initially pressing on the gas. I checked the obvious stuff ie: plugs, air cleaner, wires etc...I'm not a mechanic but a friend had mentioned the carburator might need adjustment because of the change in climate and elevation? Any truth to that and without really screwing it up, how do you do it? Thanks for the help in advance.
Sounds like the accelerator pump in the carb may not be quite up to par . . .
Hi, I have the same setup as you do. I have had the same problems with hesitation. I changed the filter in the carb and completely removed the fuel line inline filter. I bought a carb tuneup kit and got it professionally done. My steel fuel line going into the carb had a slight bend in it and upon replacement I noticed some change. I found that the cleaning of the carb made the most difference. . It was fine for about a week. BUT, I still get some hesitation. I know this probably isn't going to help much, but I just wanted to let you know that you are not alone. :)
I have wondered about the fuel sending unit. I have yet to check to see what the fuel pressure is at the carb. I have always wondered: I am getting enough fuel, or too much fuel and therefore flooding out the carb?
This has always been something that ****es me off about my car. SO, if you hear anyhting from one of the other members, let me know. :)
Sorry I couldn't be more help.
Scott :w
Its very easy to check the accelerator pump in the carb. With the engine warm and off, simply remove the air cleaner lid, and while looking straight down into the primary barrels, snap open the throttle. You should see a good squirt of gas going into the carb. No squirt = bad accel pump = hesitation. Could also be really low float setting, or not enough gas getting to the carb due to clogged filter, but I think that is unlikely.

Don't be afraid of pulling off the carb and tearing it down yourself. If you have the Chevy service manual, they have excellent pictures and instructions. There are only a couple of tricks, and one of them is getting the accel pump lever off.

A carb rebuild kit can be had for 35 dollars or so and will include everything you need. Just a little cleaning and a new accel pump, needle/seat and float adjustment may solve your problem.

If you need any tips, just holler.

Hope this helps.
If you find that your accelerator pump is functioning properly, the next place to check is timing. Make certain that your timing is set correct for your engine and that your vacuum advance is working. Incorrect timing or an inoperable vacuum/mechanical advance will also cause hesitation.
All of the above things are good to check. If the hesitation is only slight, just as you touch the throttle you may also want to check the idle mixture screws. The basic setting for a Quadrajet is 4 full turns out. I find that I get a slight hesitation at that setting. My car seems to like about 2 3/4 turns.
I'll be working on it this weekend, with all these posts in hand......I'll let you all know how it goes thanks for the help, and pray I don't screwwwwwwww it up. :L

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