Lost, MAD, Confused

[airforce guy]

dont know where to begin and may ramble sorry in advance...
55 Buick Super, having issues keeping it started some time back had gas tank cooked and cleaned seemed to run fine off and on, time passed and could not keep car started and if it did stay started would not drive far. Looked at fuel pump and found fine sandy substance believed to be rust, cleaned fuel pump, cleaned tank again, replaced fuel line from tank to K member area changed rubber fuel hose from fuel pump to carb, and had carb cleaned again. Now car will run after its warmed up great at idle, put load on car
(drive) it shuts off not smart with carbs seems to be carb/vacuum issue not many vacuum lines, and carb guys says carb is good to go, lost MAD confused!!!

[66electrafied]

If the fuel pump is still the original one, I'd look at it first. Get the pressure checked. If the fuel pump checks out, then look at the carb, check for vacuum leaks. Chances are if it's idling okay then that isn't going to be a problem. A fast way to check for potential vacuum leaks (to see if it's an issue) is to idle up the car and close off the air intake on the carb with your hands. (carefull though, it could backfire resulting in burns) If the car wants to die with the throat closed off, -no vacuum leaks. If the engine speeds up with the throat closed off, - there are vacuum leaks. Get a vacuum gauge, and see what it is actually registering. Low vacuum, (less than 10) usually means vacuum leaks, but could also mean a valve or a timing issue is present. Read up on how to decipher vacuum gauge readings.

Another problem could be the ignition, - the timing could be off a couple of degrees. If the points are older than dirt, get them changed. Any changes or deterioration in the ignition system will result in a lack of power. Dwell should be between 25-32 degrees, point gap .016 -.019; any deviation from that could result in lack of power. Any leaks on the vacuum advance system will also result in the engine not getting enough advance, - and lack of power. When doing ignition checks, be sure to check out the coil as well, if it's old, consider replacing it.

Basically it'll all be a slow process of elimination; start with ignition, once you're sure that's properly set, proceed to the fuel side, check for fuel pump pressure, and then vacuum leaks. These cars are very simple; it needs only air, gas and spark to run. You've got it running, so it should just be a matter of tweaking it.

To tune a stock vintage Buick I usually only use a timing light, dwell meter, and a vacuum gauge. These are usually all a person needs to keep an old engine alive, and to diagnose general engine health. A compression gauge is also nice to have, and helps with potential trouble shooting.

Hope this helps...