Spectrum 3.0L GM, Parts & Service Manual

Page: 43 / 327

43
HESITATION, SAG, STUMBLE
Checks Action
DEFINITION: The engine has a momentary lack of response when accelerating the engine. The condi-
tion can occur at any engine speed. The condition may cause the engine to stall if it’s severe enough.
Preliminary Checks None.
Fuel System Checks

Check the fuel pressure. Refer to
Fuel System Diagnosis
.

Check for low fuel pressure during a moderate or full throttle accelera-
tion. If the fuel pressure drops below speci fi cation, there is possibly a
faulty low pressure regulator or a restriction in the fuel system.

Check the TMAP sensor response and accuracy.

Check Shut-Off electrical connections.

Check the Regulator, Venturi and Throttle body for proper installation
and leakage.
Ignition System Checks
NOTE: Natural Gas and Propane require higher secondary ignition system
voltages for the equivalent gasoline operating conditions.

Check for the proper ignition voltage output with
J 26792
or the equiva-
lent. Verify that the spark plugs are the correct type and properly gapped.

Check for faulty spark plug wires.

Check for oil fouled spark plugs.
Additional Check

Check for manifold vacuum or air induction system leaks.

Check the alternator output voltage.