Need Help with car/ not running good

[kustumizer]

Ok, my comet has been acting really weird the past few days. I think i have down to a fuel problem.This problem just started a few days ago. When you first take off , the car will studder and when you give it more gas it just studders worse, then i shift to second and it goes good for about a sec or two, the i shift to third and you can cruise but cant make it over 60 miles per hour or it will start to studder. The car was doing yesterday morning then i got the car home and it sat for a hour or so then i went outside to back it out of the garage and it drove fine for the rest of the night. Then this morning it acted up again?? I changed the fuel filter, clean and tuned the carb to the best i know of?? I dont know what else it might be?? Fuel pump maybe?? I know the car has had a little bit of a rusty tank and i have a really good fuel filter on it. What do you guys think that it might be?? Thanks Nate

[McGrath]

Make sure the accelerator pump on the carb is pumping. Without it, you have to ease the engine up to speed. Any sudden acceleration will make it lean out and fall on its face.

[kustumizer]

OK ill check it out! Thanks Nate

[McGrath]

Just remember that the accelerator pump can squirt a little even with a small hole or crack in it. You didn't say what carb you are running. Qjets and Edelbrocks(I think) use a plunger, Holleys and several other Factory Carbs use a flat Diaphram. The flat diaphrams are easy to change, Qjets have to be partially dis-assembled.

I had a qjet a while back that acted similar to what you are describing. Accelerator pump was squirting, so I decided the carb needed rebuilt. When I took it apart to put a Kit in it, I found that the accelerator pump plunger had a chunk missing. It was pumping, but not as much as it was supposed too. Same thing can happen with a diaphram. A small crack can allow part of the fuel to bypass, but it usually shows as a visible leak on the outside of the carb.

[kustumizer]

OK thanks for the info. The carb im running is a 1 barrel motorcraft on a 170 cubic inch 6 cylinder. The only time the car studders is when its in gear, yo can out in neutral and rev it and its fine then when you take off in gear is when it acts up?? Thanks for your help. nate

[McGrath]

Check all your vacuum ports and hoses too. Sometimes a vacuum leak will only cause problems when the engine is under a load.

It could also be ignition. A weak coil can let the engine fire, but under a load such as accelerating in gear, the spark can be weak enough to not fire the added fuel. Look at the points in the distributer and make sure they are clean, in good shape, and have the proper gap. Make sure your plugs and wires are all in good shape.

[TINGLER]

Double check for vacum leaks. I had a vehicle that I drove with similar problems. I rebuilt the carb, etc. etc. etc.... Finally I found the problem. It was a vacum leak on the back of the intake.

However, my vehicle acted the same way all the time. It was constant....
So maybe yours is another problem. Check for vacum leaks anyhow.

If I am not mistaken, you recently overheated that engine. Could it be that these are some symptoms caused by that event? Maybe by chance the intake has developed a leak? Again check for vacum leaks. Overheating an engine does funny things to it. I recently experienced an overheated engine and afterwards it ran fine. It was however puking antifreeze out the radiator overflow like crazy. When I tore it all down, I found that I popped the head off of a head bolt which allowed the head gasket to leak.

Also, the rusty tank is not good in any situation. I always try and make that a priority to have a clean tank. I've heard many stories about lots of funky stuff happening when rust finds its way into the carb.

Keep plugging away at it. Old cars are a pain in the ass! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

VT.

[TINGLER]

Ahhh, bftwcs beat me to it....

[McGrath]

Ahhh, bftwcs beat me to it....

Not really. It was an afterthought for me, you thought of it right off the bat. http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[2tall2beahotrodder]

Its probably is the fuel system..
but my cutlass was doing that a while ago.. It would stuttered, then act up some more, and just stall out, when its in 3rd gear at 50-60 mph...
After a week of putting up with that bull shit, i changed all the sparkplugs, new oil filter, and switched oil to penzoil.. car ran fine untill a few days ago.. It needs a new carb, but im too lazy.. http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif


steve-

[kustumizer]

well i went outside and checked it. I checked the vaccum on the fuel pump and that was fine the i checked the vaccum from the distributor to the carb and i cleaned it out then i started it up and and it drove like a charm down the street. Im going to go take another ride and tell you how it went!! Thanks Nate

[recycler]

If none of that helps check the rubber lines between tank and steel line, steel line and pump, and pull the sending unit/pickup tube. The runbber lines can fall apart on the inside allowing flaps of rubber to hang inside the hose. Oh,also, look over the steel line and make sure it isn't pinched anywhere. Brad

[DrJ]

Check if all your plug wires are on tight, and in good condition, (look at them for spark arcs while running at night.)
I had a car doing that once and it ws because one of the Distributor cap clamps wan't fastened down and the cap was bouncing up and down like a loose lid. I don't know why it ran at all!
Could also be a choke coming off too soon, and running lean while still cold.

[34Hupmobile]

I'd suspect a clogged fuel sock in the tank. When you move the car around ie acceleration, the crud in the tank migrates toward the pickup tube helped along by the pump vacuum effect. Since the pump is sucking from the tube the sock gets wrapped up with crud, rust etc. Fuel delivery can't meet demand. When you turn the car off and let it sit for a bit the crud falls off the sock so it will start right up again and usually run fine for a short while. Or it may be the carb.

[McGrath]

"I checked the vaccum on the fuel pump "

Just in case you don't know, Accelerator Pump and Fuel pump are two different things. The Accelerator Pump is on the Carb itself and gives the carb an extra "Squirt" as the throttle opens. If you look down inside the Carb and open the throttle(with the engine off) you should see a strong stream of Gas squirt into the Bore of the Carb.

Under steady operation, the Downdraft of air through the Carb draws gas out on its own. During acceleration, the draft does not change the fuel ratio fast enough on its own to keep from leaning out. That is what the acclerator pump is for. Anytime you accelerate, even slightly, the accelerator pump gives an added shot of fuel to the Carb.

[kustumizer]

no i didnt mean the accelerator pump, their a vaccum on the fuel pump and i checked how the vaccum was on it! I drove the car 3 towns over and it ran fine all the way their then i went into the shop to pick up my paint and some body stuff, the car wasnt shut off for 5 minutes and i came back out and started it up and it acted up again, so i got it to the next store which was a burger king so i went in to get something to eat to let it cool down, then i came back out in a half hour and it studdered a tiny bit at first then drove good the rest of the way home. I think its what hupmobile said because what he said is pretty much what happens. Well since im doing the body work on the car right now and painting i decided im going to take the car off the road for a few weeks and pull the motor and do it over and clean everything up and get a new tank for it. Thanks For all the help guys!!! Nate