Hey Guys,
My little brother is having a problem with his car. Its not a Chevelle but it is a 1985 Chevy Impala. The car has less than 50K on the 305 4bbl. The problem is that he has been driving the car trouble free until he put half a tank of Amaco (87) in it the other day. Since then it starts fine but doesnt want to keep running, he has to keep giving it gas at stop lights and signs. I told him to top off the rest of the tank with 93 octance and a couple bottles of heat. The problem continued. The carberator was remanufactured in 2005. Today I checked the fuel filter (only 4 months old) and made sure that the fuel pump was pumping adaquately. Still the problem continued. I took a look at the cap, rotor, and plugs all of which were the originals (the wires were newer) and still have the problem. Now I realize that the only variable to change was the fuel from Amaco, but i figured that the bigger names had more reliable fuel than the Citgo's and whatnot. Anybody have any ideas? Or know of any other forums I can check? Somebody I know mentioned maybe it would be an idle positioning sensor? Should we siphon out the entire tank? Please help guys :confused::confused::confused:

It's a 22 year old car. I'd change the plugs, cap, rotor, belts, and filters all just for good measure, as well as clean the carb. And if one of those fixes it, you're good to go! If it still runs rough, then dive deeper. And don't worry about th money on the other stuff- you'd need to change them eventually, and you can rest easy knowing the normal wear parts are new.

Hello ! Problems like this are so hard to pin point without seeing the car in person and being able to poke around to make sure evrything is working properly . But if I had to guess , I would say that the fuel has nothing to do with the problem . It sounds to me like maybe the choke is not working properly . Will the car idle on its own after it warms up to normal temperture ? or is it okay untill it warms up ? I'm thinking maybe the choke is stucking in an almost closed or wide open position . Pop the air cleaner off when its been sitting ( maybe overnight or at least a couple hours ) , and see what positing the choke is in . And what happens after the car warms up to normal operating temp . And make adjustments as nessary .
As I said , its very hard to trouble shoot these types of problems when the car is not infront of me . Keep us posted and maybe we can help narrow it down .

I forgot to post that we changed the plugs, cap, rotor, and fuel filter today and although it sounds a little healthier. The car starts fine when cool and you can hear the choke cause the idle to raise. And it seems, I have even kicked the idle down and let it sit idleing for a few minutes. Then we backed it out of the driveway and as soon as he stopped to put it in drive it died. I also died at the next stop sign, seemed to bog a little when he got on the gas a little.

Is the check engine light on? Another area to look at is the catalytic convertor. These can plug and cause idling problems at first and then get to a point of the engine not running at all. Feel the exhaust flow if it seems weak the convertor may be restricted. A muffler shop can check it with a pyrometer to see if it needs replaced.

The converter could be clogged, the TPS switch in the carb could have gone bad, the module in the distributor could be going bad, clogged EGR valve, O2 sensor. There are quite a few variables on that car that can cause that type of condition.

Anybody know a site where they might show pictures of the location of tps switch, egr valve, and o2 sensor on this engine?

does it have a lockup convertor, Had one in a camaro that the switch went bad. everytime you stopped the car would chug and stall. easy to check if it has it, just unplugg the wire to the trans. if thats it it will run fine

The TPS switch is the blue thing sticking out of the top left front of the carburetor. The EGR valve is mounted on the right side of the intake manifold and the O2 sensor is drilled into the left side exhaust head pipe. I forgot about the lockup switch at the trans. The plug for that is on the left side of the transmission.

Thanks for your help guys, do you think that autozone napa or advanced would carry these parts?

No chance he got a little water with his gas is there? Sounds like a problem I had years ago, big pain in the gas to get rid of too. Drain the tank, flush the lines, change the filters, add some white gas, then she was good to go. Then again it could be something else...
Bruce

Thanks for your help guys, do you think that autozone napa or advanced would carry these parts?

They all should have them in stock.

Edit: One other thing to check for are vacuum leaks. Check all the vacuum lines (there are about a million of them on that car) for dry rot, splits, and make sure they are all connected to where they are supposed to be.

I'd recommend NOT replacing the EGR valve unless it is totally shot. Replacement EGR valves often don't work as the engine requires and may even make the thing run worse. I'd suggest you remove the original EGR and gently clean the carbon off of it and reinstall it. If it's really shot, get a new one from a GM dealer as the generic parts store ones will not function correctly for your engine.

No chance he got a little water with his gas is there? Sounds like a problem I had years ago, big pain in the gas to get rid of too. Drain the tank, flush the lines, change the filters, add some white gas, then she was good to go. Then again it could be something else...
Bruce

I was thinking the same thing.
If all he did was put gas in it and it started running bad.