Fuel System - Yamaha MM700A Manual

48
heavy duty jumper cable (Figure 19). Interpret the results
as follows:
a. If the starter motor ran, test the main switch and en-
gine stop switch as described in Chapter Six.
b. If the starter motor did not run, the starter relay is
faulty. Replace the starter relay.
Starter Testing
However, the starter motor must be disassembled to per-
form the tests. Refer to Chapter Six.

FUEL SYSTEM

Many snowmobile owners automatically assume that
the carburetor is at fault when the engine does not run
properly. While fuel system problems are not uncommon,
carburetor adjustment is seldom the answer. In many
cases, adjusting the carburetor only compounds the prob-
lem by making the engine run worse.
Start fuel system troubleshooting at the gas tank and
work through the system. reserving the carburetor as the
final point. Most fuel system problems result from an
empty fuel tank, a plugged fuel filter, malfunctioning fuel
pump or sour fuel. Figure 20 provides a series of syrnp-
toms and causes that can be useful in localizing fuel sys-
tern problems.
Carburetor starting enrichment valves can also present
problems. A starter enrichment valve that fails to open
eauses hard starting problems. Check carburetor starter
valve operation and adjustment (Chapter Three).
Positive lead
Starter
motor
Identifying Carburetor Conditions
Refer to the following list when trying to determine rich
and lean carburetor conditions.
Rich
I. The spark plug(s) are fouled.
2. Rough idle.
3. Blubbering under acceleration or load because the en-
gine does not fire on each stroke.
5. Black, sooty appearance of exhaust pipe.
Lean
appearance.
2. The engine overheats.
3. Acceleration is slower.
CHAPTER TWO