SPARK PLUG FOULING CORRECTION REPLACE PLUGS AND VACUUM BRAKE

Spark plug fouling can occur on early production vehicles subjected to repeated short trips. This could then result in a possible no start, rough idle or poor performance condition.

The following actions will reduce the possibility of spark plug fouling and are recommended for vehicles that exhibit this condition.

(1) Replace carbon fouled spark plugs with the following:

VEHICLE ENGINE RPO SPARK PLUGS

"A" AND "X" LE2 R43CTS "F" LC1 R43CTS "X" HI OUTPUT LH7 R42CTS "S" TRUCK LR2 R43CTS

(2) Reset primary vacuum break to revised settings listed below by turning adjusting screw counter-clockwise.

When making primary vacuum break adjustment, it may become necessary to adjust (lengthen) the air valve rod to obtain revised setting. See service manual for instructions.

VACUUM BREAK SPECIFICATION

ENGINE TRANSMISSION REVISED SETTING

LE2 Automatic 300 LE2 Manual 320

LCl Automatic 300 LCl Manual 320

LH7 Automatic 320 LH7 Manual 320

LR2 Automatic 300 LR2 Manual 300

After making these adjustments, the vacuum can should be painted with a black stripe.

(3) Adjust the air valve rod as shown in the service manual and set to specification (10).

(4) Adjust choke unloader to 45 DEG on all engines except the LR2 "S" truck. Adjust "S" trucks to specification listed in service manual.

In addition to following the procedures outlined above, assure that the engine timing and fast idle adjustments are per vehicle emission label specifications and that engine oil is not fuel contaminated.

Labor Operation: T0065

Labor Time .9 Hours

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.