Engine Fuel System - GMC 1977 motorhome Operating Manual

Gasoline Fuel Filler Compartment
Fuel Filter Components
Removing Engine Air Cleaner Element
84
1 . Allow engine to cool . While engine is cool-
ing, visually inspect radiator, engine, all cooling
system hoses for source of low coolant level, and
correct problem if possible.
2 . If leakage problem cannot be readily
corrected, do not run engine until vehicle is re-
paired and refilled by a qualified mechanic .
3. Refill cooling system by performing Steps
8-11 of "Draining and Refilling".
THERMOSTAT
The cooling system is protected and con-
trolled by a thermostat installed in the engine
coolant outlet to maintain a satisfactory operat-
ing temperature of the engine. This thermostat
is designed for continuous use through both
winter and summer and need not be changed
seasonally . When replacement is necessary,
Delco parts are recommended.
ENGINE FUEL SYSTEM
FUEL REQUIREMENTS
Your vehicle's engine is designed to operate
on unleaded gasoline which minimizes spark
plug fouling and emission control system de-
terioration . Regular grade leaded gasoline may
be used under normal operating conditions and
also to eliminate knock. Knock is a metallic
rapping noise generated during the combustion
process . If knocking persists, consult your
authorized dealer. Continuous or excessive
knocking may result in engine damage and con-
stitutes misuse of the engine for which GMC
Truck and Coach Division is not responsible
under the terms of the New Vehicle Warranty .
The engine does not require Premium grade
fuel . Therefore, its use would be an unnecessary
additional expense.
If an unleaded gasoline is used it must meet
the minimum octane specifications established
by the Federal government. In compliance with
Federal regulations, pumps dispensing such
gasoline are labeled with the word UN-
LEADED .
FUEL SYSTEM
The vehicle has two gasoline tanks of ap-
proximately 25 gallons each and a fuel switch-
ing device (see "FUEL SELECTOR" switch)