Floscan TwinScan GPH/LPH Meter - Manual (Page 20)

8/30/2004 1000-204-00C
FloScan Instrument Company, Inc. Tel: (206) 524-6625 Fax: (206) 523-4961
3016 NE Blakeley Street, Seattle, WA 98105 Email: [email protected] Http://www.floscan.com
• The Sensor(s) may be defective if voltage readings in steps 3 & 5 remain constant.
• If signal voltages in steps 3 & 5 are ok, go to the backside of the Instrument. With engine(s) running, measure and record voltage
readings across the Red/White & White, (Port Sensor) and Red & Brown, (Starboard Sensor) signal wires. These voltage readings
should match the Sensor’ readings. This verifies that the Sensors’ signal output is reaching the Instrument. If not there is a wiring
problem.
V. CONTINUITY TEST
1. Continuity testing requires access to the back of the Instrument and an Ohmmeter. It verifies that wires are not broken, shorted
to ground, another wire, or to power. Before starting, secure all power. You will be testing the WHITE, BROWN, and BLACK
wires.
2. Disconnect the WHITE and BLACK wire harness conductors from the WHITE and BLACK Port Sensor
& Instrument wires. Connect a jumper from the WHITE wiring harness conductor to a known good ground.
At the Instrument, connect an Ohmmeter lead to its’ WHITE wiring harness conductor. Connect the other ____________
Ohmmeter Lead to a known, good ground. The Ohmmeter should read approximately 0.1 to 3
Ω.
(Ohm Reading)
Connect a jumper from the Black wiring harness conductor to a known good ground. At the Instrument
connect an Ohmmeter lead to its’ Black wiring harness conductor. Connect the other Ohmmeter Lead to
____________
a known, good ground. The Ohmmeter should read approximately 0.1 to 3
Ω. (Ohm
Reading)
3. Disconnect the Brown and BLACK wire harness conductors from the WHITE and BLACK Starboard Sensor
& Instrument wires. Connect a jumper from the BROWN wiring harness conductor to a known good ground.
At the Instrument, connect an Ohmmeter lead to its’ BROWN wiring harness conductor. Connect the other ____________
Ohmmeter Lead to a known, good ground. The Ohmmeter should read approximately 0.1 to 3
Ω.
(Ohm Reading)
Connect a jumper from the Black wiring harness conductor to a known good ground. At the Instrument
connect an Ohmmeter lead to its’ Black wiring harness conductor. Connect the other Ohmmeter Lead to
____________
a known, good ground. The Ohmmeter should read approximately 0.1 to 3
Ω. (Ohm
Reading)
VI. PULSATION PROBLEMS
A stiff anti-siphon valve, sticking carburetor float or miss-plumbed Pulsation Damper(s) can cause fluctuating GPH readings. These are
most pronounced at low Rpm’s and tend to disappear around mid throttle. They are annoying, but won’t affect totalizer accuracy. To
eliminate, repair or replace any defective parts, or re-plumb dampers according to the Fuel Flow Schematic Instructions.
VII. FINDING FUEL SYSTEM VACUUM LEAKS
Fluctuating GPH and High Totalizer Readings are usually caused by a small vacuum leak between the fuel tank and fuel pump inlet.
Fluctuations tend to be between 2 and 4 GPH. These vacuum leaks also affect totalizer accuracy, causing it to read 15 to 100% high.
Larger leaks produce greater fluctuations and higher readings. They generally do not affect engine performance.
Finding suction leaks can be time-consuming. When approached properly, they can usually be found and repaired quickly. Two
common places for suction leaks to occur are at the primary fuel filter - water separator, and/or a loose valve stem packing nut.
Remove the filter housing and coat all o-rings, gaskets and sealing surfaces with a medium to heavy grease, (Do not use oil) and
reassemble. Grease all valve stem packings and gently tighten gland nuts. Don’t over tighten, valve handles should turn freely.
Tighten all hose clamps and compression fittings. Don’t over tighten. Run the engine for 5 to 10 minutes observing GPH readings. If
you’ve found the problem, fluctuations should be reduced to less than ½ GPH.