Mechanical Diaphragm Fuel Pump For Model 490000; Volumetric Test - Briggs & Stratton VANGUARD M490000 Repair Manual

MECHANICAL DIAPHRAGM FUEL PUMP FOR MODEL 490000

Volumetric Test

Perform a volumetric test to verify that the proper
amount of fuel is being delivered to the engine. See A
of Figure 32 for a typical fuel flow diagram for Model
490000. Proceed as follows:
1. Relieve fuel system pressure. See CHECK/RELIEVE
FUEL SYSTEM PRESSURE in this section.
2. Remove battery negative cable (black) from battery
negative (-) terminal.
3. Squeeze clip at fuel outlet port and remove hose to
fuel pump module.
NOTE: Wrap shop towel around fitting to catch any
fuel leakage.
4. Obtain a stop watch and a graduated cylinder.
5. Attach suitable hose to fuel outlet port and direct free
end into graduated cylinder. See B of Figure 32.
6. Install battery negative cable (black) to battery
negative (-) terminal.
7. Start engine and watch for fuel discharge from outlet
port hose. Start the stopwatch as soon as fuel flow is
observed.
8. Run engine for 30 seconds at 2200 RPM.
9. After the time has elapsed, turn off the engine and
stop the watch.
10. Measure the volume of fuel discharged into
the graduated cylinder. See the table below for
the approximate amount of fuel that should be
discharged.
Pump Fuel for 30 Seconds
Approximate Fuel Amount
NOTES:
• Position the fuel tank so that it is near level
with the fuel pump. Do not place the graduated
cylinder BELOW the fuel pump or gravity feed will
produce false results.
• The engine will run longer than the 30 second
test interval using fuel trapped in the fuel pump
module.
• View the graduated cylinder with your eyes
directly level with the fuel. Note that the fuel
curves up the sides of the graduated cylinder.
This curve is called a meniscus. For the most
accurate reading, read the measurement from the
bottom of the meniscus.
237 m
0.5 pint
0.25 quart
1.0 cup
• The volumetric measurement is only
approximate. The fuel pump is likely functioning
properly if the test results are within 10% of the
approximate fuel amount.
Engine Cranks But Will Not Start
Use the starter to turn the engine over for 10
seconds. See the table below for the approximate
amount of fuel that should be discharged.
Crank Engine for 10 Seconds
Approximate Fuel Amount 65 ml
0.13 pint
5
0.06 quart
0.27 cup
135