Hesitation

[moliva1568]

When car is stopped and I hit the gas to take off, the car hesitates like it's gonna cut off and then picks up and goes. This happens when i'm taking off from light and pulling out of driveway. It even happens when the car is in park and i hit the gas pedal to rev the engine (not that i have a habit of doing that, just FYI). Any idea what may be causing this?

[j cAT]

Originally Posted by moliva1568

When car is stopped and I hit the gas to take off, the car hesitates like it's gonna cut off and then picks up and goes. This happens when i'm taking off from light and pulling out of driveway. It even happens when the car is in park and i hit the gas pedal to rev the engine (not that i have a habit of doing that, just FYI). Any idea what may be causing this?

could be timing is incorrect,,,,could be a vacuum leak...
what engine / year is it ?

[moliva1568]

it's a 1984 caprice with the 305 motor. thanks

[j cAT]

Originally Posted by moliva1568

it's a 1984 caprice with the 305 motor. thanks

that set up has many feet of vac. hose...also the pcv hoses and the PCV should be replaced....then when the vac system is not leaking and the vac guage reads about 19-21 inches ...the egr may be the problem....opening too much, weak spring from age/heat...

re-torque the carb screws/bolts but not too tight...
replace the fuel carb filter as well..

[NOVAZ27]

You have a Q-jet Carb. More than likely the accelerator pump is worn out. Or the hot air warm up tube,(flexible pipe from exhaust manifold to air breather snout), has become dislodged/missing. These items will cause the engine to stumble during cold weather. After the engine warms up it is not as noticeable. My *84" has done the same thing as yours. The PCV valve can be cleaned up with some carb cleaner spray. They usually gunk up in the winter time. After cleaning check the spring/ball valve in PCV. If it rattles it is usually ok. It is a cheap item if you want to replace it however.
Like the other responders wrote snug the carb down, check the vac. hoses, fuel filter etc. If you have some carb cleaner left over you might spray the carb linkages + choke & throttle plates of the carb. Black gunk will form on the backside of the plates. Be carful when spraying. use adequate ventilation on a cold engine. If your car runs all right after it warms up your timing is probably OK. You might consider a cap/rotor/sparkplug & wire change. A weak coil will cause problems also. I had one that was slowly going bad. It caused hesitation under load but would idle fine.
Hope to have helped you here.
I have had my CAPRICE since "89" learning a lot in those last 20

[Blt2Lst]

I agree with the accelerator pump.
Time for a carb rebuild, also replace all the vacuum tubing while you are at it.

[tyriekfv]

My car has recently started doing this as well. Mine is a 92 caprice with a 305 5L. Could the fuel filter also cause this?

[silicon212]

To the OP - does the hesitation sometimes result in a backfire? If so, check the vacuum on the engine - you may well have a worn camshaft. Vacuum in the normal range on these engines, is around 15-17 inches Hg, at 900 RPM. If the vacuum gauge pulses (as opposed to holding steady), there might be a couple of causes, one of which is a worn camshaft. If you hear a click-click-click in rhythm with the engine RPM from the top of the engine, aka valve noise, this is another argument in favor of the worn camshaft theory.