Floscan 9000-20B-1 GPS Interface System - Manual (Page 24)

8/30/2004 7000-044-00D
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
2. Verify that wiring connections are tight, clean and dry. Check continuity while shaking the wires. Ohm readings should be
near zero and remain steady.
3. Verify that the tachometer signal wires are connected at the correct signal output point.
VII. 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.
VIII. 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.
If the problem persists, temporarily install a clear piece of fuel resistant hose downstream of the forward flow sensor. Run the
engine and watch for a stream of small bubbles in the clear hose, or an occasional larger bubble. Sometimes shining a light through
the hose makes bubbles easier to see.
Observe the clear hose while shaking the fuel lines. If the bubble stream continually increases or decreases you’ve found the leak
area. Repair or replace as needed. If this occurs one-time, you probably dislodged some trapped air.
If the leak hasn’t been found, the last step is to inspect each pipe joint. Thread sealant should be visiable around each joint. If not,
that joint is suspect and must be resealed. After resealing run the engine for a few minutes to purge any remaining air. There should
now be bubble free fuel running through the clear hose. If bubbles are still present a leak was missed. Recheck your work. After all
the leaks are stopped, remove the clear hose.
IX. FUEL FILTERS
A dirty fuel filter, or one that is too fine (1-25 micron) will draw vapor bubbles out of the fuel, causing fluctuations and high
readings. Replace it with a new 30-micron or coarser filter.
X. FLOW SENSOR ORIENTATION
Sensor orientation is critical for proper operation. All Sensors have their inlet and outlet ports clearly marked (IN / OUT or Î Î).
This identifies fuel flow direction. The Sensor must be, “Plumbed” correctly for it to operate properly. There is an additional single
arrow on the Sensor body. It is crucial that this single arrow points up Ï.
XI. LOW RPM OPERATION
At idle, under a no load condition, it is common for GPH readings to fluctuate slightly.