Pinging, Run-on and Hesitation

[bf2knight]

I need some advise. I have a 75 LeSabre with a 350 and about 110M miles. I've been very busy this spring and early summer so I haven't really had time to get the old beast out too much. The few times that I have had it out the engine has run terribly. When I first start it (and it fires right up) it runs fine. After just a few minutes, it runs like garbage. I'm going to assume the culprits are the gas and the carb. First of all, when I step on the accelerator, it nearly quits. I have to pump it to get it moving. Once moving, as soon as I hit second gear, it pings like mad and when I get back home and shut it down, it runs on for 30-60 seconds. But it starts right up again whether hot or cold. I had the carb rebuilt last summer. I assume the carb needs adjusting and I'm pretty sure that the gas is getting old. I tried to siphon it out, but can't and I have nearly 1/2 tank (and that's about 12 gallons). I'm not good with carbs and need to try to find a good mechanic in the southern Twin Cities, but it's hard to find someone whose willing to work on carbs. Any suggestions would be helpful.

 

[theoldguy]

I would suggest that the simplest way to remove the old fuel, and make it run properly is to " Drive the thing" 12 gallons will take you 150-200 miles and when you get home the car will probably run better than it has in a long time. It will take that many miles just to limber the old car up!

 

[Syndicated]

Your number one problem it sounds like it bad gas.
Most people think that gasoline will last a year before going "bad".
This isn't true. Gasloline looses most of it's volatily within 3 months without a stabilizing agent. This leads to knocking and hard starting conditions because the octane evaporates.
Either take your car on a long trip or siphon all that gas out. There isn't too many options there.
As for the can running for up to a minute after you shut it off, this is called dieseling. The biggest cause of this is ignition timing. Check and adjust your timing to what the manufacturer calls for. If the problem persists, then you need to start playing with your timing so that it's either advanced enough or retarded enough that this problem goes away.