stalling problem

[alecmcmahon]

car: 1984 Pontiac Trans Am


i just bought this car about 2 weeks ago, i was told the carberator had a " flat spot ", ( i dont know much about cars ) and when i start the car up and leave it, about 10 seconds later, the engine dies down and stalls, maybe its the idle? ( how do i just idle ? ) any ideas?

[FAPhoenix]

i just bought this car about 2 weeks ago, i was told the carberator had a " flat spot ", ( i dont know much about cars )

A flat spot I believe is a higher RPM problem/setting which you'll start revving up then flatten off before continuing.



Kinda like that.

and when i start the car up and leave it, about 10 seconds later, the engine dies down and stalls, maybe its the idle? ( how do i just idle ? ) any ideas?

Going to need more information as it sounds like two possible things, one is too little gas and the other is flooding.

When it stalls do you need to floor it to restart it?

[alecmcmahon]

no, i dont have to floor it to start it back, up, ... it starts up just like ussual.



how do i fix a flat spot?

[FAPhoenix]

1) Does it stall when you try to accelerate or just when the car is sitting there?

2) Is it when the engine is hot or cold or all the time?

3) Does it do it in gear or neutral or both?

4) Is it stock carb?

5) If aftermarket what brand of carb is it?

6) 4bbl or 4bbl HO engine trim?

[alecmcmahon]

Originally Posted by FAPhoenix

1) Does it stall when you try to accelerate or just when the car is sitting there?

2) Is it when the engine is hot or cold or all the time?

3) Does it do it in gear or neutral or both?

4) Is it stock carb?

5) If aftermarket what brand of carb is it?

6) 4bbl or 4bbl HO engine trim?

1- no, it doesnt stall when accelerating, ... i have to keep my foot on the gas, reving the engine, to keep it alive- When i let it sit, it stalls

2- it happens all the time

3- it does it in gear, netural, etc.... and in park

4- i do belive it is the stock carb.

5- ( see above )

6 - uhh, dont really know what that means, but HO doesnt sound familar with anything about the engine




hope that helps, if i brought the car for a " tune up " would it fix the problem, or would i need a new carb?

[FAPhoenix]

Sounds like your engine is idling too low. Below are some reasons it might be low:

o Timing is Out
o Advance Mechanisms (Vacuum or Mechanical)
o Choke (Ruled out by non flooding condition)
o Plugged Air Cleaner (Ruled out by non flooding condition)
o Not Firing on all cylinders (Check your plugs and wires)
o Idle Mixture Adjustment (One screw on each side)
o Idle Speed Adjusment (Pictured Below)

Either way here is how to set your idle on a Rochester Quadrajet. This is a picture of a 68 Pontiacs so your might differ slightly. You're looking for something like this:



Screw the bolt in and out to adjust the idle speed. It will probably adjust between 500-750RPM I believe.

I would set it as high as possible for idle speed and if that doesn't work we'll look at the others.

[alecmcmahon]

Originally Posted by FAPhoenix

Sounds like your engine is idling too low. Below are some reasons it might be low:

o Timing is Out
o Advance Mechanisms (Vacuum or Mechanical)
o Choke (Ruled out by non flooding condition)
o Plugged Air Cleaner (Ruled out by non flooding condition)
o Not Firing on all cylinders (Check your plugs and wires)
o Idle Mixture Adjustment (One screw on each side)
o Idle Speed Adjusment (Pictured Below)

Either way here is how to set your idle on a Rochester Quadrajet. This is a picture of a 68 Pontiacs so your might differ slightly. You're looking for something like this:



Screw the bolt in and out to adjust the idle speed. It will probably adjust between 500-750RPM I believe.

I would set it as high as possible for idle speed and if that doesn't work we'll look at the others.

the picture looks almost exact..... but how exactly am i adjusting that thing.... screw driver? wheres the screw? do i just un-screw it to the left so it comes out more?

[FAPhoenix]

Use a small wrench to unscrew it slowly while it is idling, but if it doesn't idle guess and check by changing it then turning on the car, if it stalls change again and test.

Remember that is just the idle speed (RPM's your car will idle at). Check out those other possible stalling causes.

[alecmcmahon]

Originally Posted by FAPhoenix

Use a small wrench to unscrew it slowly while it is idling, but if it doesn't idle guess and check by changing it then turning on the car, if it stalls change again and test.

Remember that is just the idle speed (RPM's your car will idle at). Check out those other possible stalling causes.

alright, so let me get this strait before i attempt to play with it myself...



i want that little bolt thing to come out so it is touching, holding the other peice up with some pressure, so the idle is higher? my bolt looks almost like that, there is alot of space between the 2 peices..... do i want them to touch ?

[FAPhoenix]

i want that little bolt thing to come out so it is touching, holding the other peice up with some pressure, so the idle is higher? my bolt looks almost like that, there is alot of space between the 2 peices..... do i want them to touch?

If there is a lot of space that means your choke is on, take it off.

If there is a little space like mine don't worry because when it turns on it will move to hold the throttle linkage higher which will mean more gas at idle which means higher idle RPM's. Only move the bolt a little bit out.

Have you checked your plugs/wires and timing yet?

[alecmcmahon]

Originally Posted by FAPhoenix

If there is a lot of space that means your choke is on, take it off.

If there is a little space like mine don't worry because when it turns on it will move to hold the throttle linkage higher which will mean more gas at idle which means higher RPM's. Only move the bolt a little bit out.

Sorry for such general terms etc. as I'm not an expert just a hobbiest.

PS Have you checked your plugs and wires yet?

alright, i as i understand, that little arm that pushes in and out is called a plunger,i think... and it moves to hold the throttle, to keep the car alive while idleing right? ... well... you told me to turn it to the left, it doesnt move? it moves up and down , as i can push and pull it with my finger

i dont know where this adjustment idle screw is..... and is there suppused to be a wire connecting to the back of the plunger? ... as i was looking at it before, it looks like there is a wire right near it thats not connected to anything, the tip is threaded, but i cant see if it goes in to the back of the plunger thing

[FAPhoenix]

Hmmm, do you have a picture of this?

Remember it could also be plugs and wires or timing, have you checked that out yet?

The idle mixture we will worry about last.

Try putting in all new spark plugs and wires that might help and won't hurt as long as you buy the correct ones.

Timing, you'll need a timing gun for or a friend with one to help with.

[FAPhoenix]

There should be a wire going to it that is alive when the ignition is on and dead when the car is off. (Look at mine, black wire into it).

This solenoid is used to allow the carburator butterfly valves to close more than the regular idle setting to prevent dieseling/run-on when you turn the ignition off.

Try hooking up the wire before adjusting it.

Remember before when I stated that if there was a lot of space the choke was on, well this is how to take it off:

While the car isn't running

1) Hold the choke flap open with your finger (front most flap)
2) Blip the throttle
3) Choke should disengage

Now you can work on the solenoid.

When you turn the ignition on you should see the solenoid move.

[FAPhoenix]

Any updates?

[FAPhoenix]

C'mon, I wanna know if I helped you fix it dammit!