Hesitation, Sag, Stumble

Definition: Momentary lack of response as the accelerator is pushed down. Can occur at all vehicle speeds. Usually most severe when first trying to make vehicle move, as from a stop sign. May cause the engine to stall if severe enough.

^ Perform "Diagnostic Circuit Check - Calif"

^ Perform "System Performance Check - Calif."

^ Visual (Physical) Check:

- Vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label.

- Ignition wires for cracking, hardness, and proper connections, at both distributor and spark plugs.

- Wiring for proper connections, pinches and cuts.

^ Make sure hot air tube is connected to air cleaner.

^ Check proper operation of THERMAC.

^ Note: Cold engine only - check the following for sticking or faulty operation:

- Carburetor choke, including vacuum break, throttle linkage and fast idle cam.

- Check choke TVS if used.


- Check all choke adjustments, including vacuum breaks.


^ Check float level using external float gage.


^ Check carburetor accelerator pump operation.


^ Check vacuum hose to vacuum sensor for leaks, restrictions, and proper connections (should be manifold vacuum).


^ Check EGR valve operation, Chart C-7.


^ Check TPS adjustment. Use ALCL tool if available.


^ Check canister purge system for proper operation


^ Check for open ignition coil ground and for intermittent ECM ground.

^ Check engine timing. See Vehicle Emission Control Information label.

^ Poor or contaminated gasoline, suggest owner try different brand.