Service Manual

3-3
Table of Contents
Two Barrel Carb./Fuel
Twin Cylinder Engine Service Manual
February 2017 - Digital Edition
TWO BARREL CARBURETOR AND FUEL SYSTEM
Components
Fuel Pump and Hoses: The fuel pump is a pulse diaphragm style pump, located on the #1 cylinder shroud. The
pulse line connects to the intake manifold above the #1 cylinder head. The change in vacuum at the #1 cylinder
intake pulses the diaphragm of the fuel pump. The vacuum supplied is a pulse, less than two psi, not a constant
vacuum that is measurable.
Fuel Filter: The fuel lter is in-line, located between the fuel tank and the fuel pump. The fuel lter has a clear
design for visibility of any potential debris or moisture. If contaminants are observed, replace the lter.
Fuel Supply and Vent Hoses: A low permeation fuel hose must be installed to maintain EPA and CARB
compliance. The fuel tank vent hose connects to the air lter manifold.
Fuel Pump Test
1. Inspection (Figure 2)
- Remove pulse line and inspect for fuel. Pulse line should not contain liquid fuel at fuel pump. Replace fuel
pump if found.
- Inspect fuel pump vent for debris blockage. Replace fuel pump if blocked.
2. Connect hand pressure tester to either inlet or outlet tting of fuel pump; block other tting.
3. Apply pressure, up to 5 psi
- Pressure should not drop.
- If pressure drops, spray soapy water mix on fuel pump to determine where air is leaking.
4. Replace fuel pump if testing failed, as it is not serviceable.
NOTE: Pulse port and vent are not pressure tested.
Figure 2
A
B
C
D
A. Fuel Inlet
B. Pulse Line
C. Vent
D. Fuel Outlet