I have a 1984 pontiac fiero when its cold it works bomb but once its warmed up its not all that whats wrong?

Cheeck the pich up modual in side the dist. It sounds like when it gets hot it cuts off the spark.

it could also be your distibutor whatever it is it sounds like as your engine gets warmer its causing somehting to expand. so something is cracked.

could be sump compression,have some1 look at the piston compression and oil rings.

Fuel pump, plain and simple. It's highly likely that your fuel pump motor has burned up. It works fine for a little while, then the motor gets hot and stops turning. It's an in-tank pump, which makes it difficult to change on your own. If you buy a new one, I recommend you use only AC delco. This is the most likely cause, but it could also be your Fuel Pressure regulator leaking vacuum. Or, it could really be a loss of vacuum anywhere. In fact, it could even be your thermostat. If the car over heats and the thermostat is bad, it won't cool the engine, nor will it tell you that your car is over-heating. Eventually the car will get so hot that it pre-burns the fuel and dies. But it will usually at least idle in this case. A CAT. converter will cause your car to gurgle to a stop before dying. A bad fuel pump will cause the engine to simply go BLANK when the gas is pressed. This is because it might still be pushing a small amount of fuel, but when you hit the "gas", you're actually opening the intake throttle butterfly valve, which allows so much air in, it's like turning off the car. There's not enough fuel to burn. It's kind of simple, really. I stick with my original decision about the fuel pump. This is a real punk to change, so I recommend just forking out the cash and taking it in, unless you just happen to have a hydraulic lift... They can check your fuel pressure in five minutes. A mechanic can also listen to sounds it makes, and gauge timing of failures, and make a sound judgment just based on that. It's alot easier to tell what's going wrong when you know what to look for. There are things you don't even know happen until someone turns you onto them. When it cuts out on you again, turn the key off, then turn it back to the ON position, not the START position, and listen very carefully for a quiet whining that lasts about one second. If you hear that sound, your fuel pump is at least slightly working. Oh, one more possibility, but highly unlikely. Your ignition coil could be burned up as well. Again, gut instinct, especially on a car that probably has somewhere around 200,000+ miles, go for the fuel delivery system.

i own a repair shop,and i think you may have a bad coil on it,,they will cause one to do that ,,also you need to check the wires that go in to the distributor on it they get dried out ,and cause fire to jump to ground on them when they get warm,,i been at this for 36 yrs,and i have worked on a few fieros ,but the distributors gave a lot of problems in these cars ,that and the coils was bad to get hot and short out,,i think if you,ll check these you might find your problem with it,,good luck,i hope this help,s.,,have a good x-mas.

A few things I would look at if I where you. Coil, although I have not seen a modern coil do this as the last guy said, I know it is possible, to check this, see if the engine is getting spark when it does not want to start again, you can either pick up a inline tester goes onto your plug and connects to your plug wire, or use an old working plug ground it to the engine and use one of your plug wires on it to see if there is spark, If there is no spark when it is hot, then check to see if there is power going to your primary side of coil, if there is, then check your coil wire going up to the distributer make sure there is power there, be careful though, this wire along with plug wires can give you a decent shock 20,000-50,000 volts, however very minimal current. If you have power going into the distributor, but its still not getting spark, check to make sure there are no cracks, remove the ECM little black \__/ almost U shapped part with a plug to it, and is held down by two small bolts in that car, bring it in and have it tested or replaced, they are $25-50. If all this checked out and you had spark to the engine, then check your fuel pressure, simple gauge that will plug into the fuel line, you can also do this step first being probably the easiest for a do it your self person. Cant remember if that one is carburated or Fuel injected, but carburated should run 8-13psi and fuel injected should be 40-48psi.