Floscan 5A20-20A-1 AccuTroll & CruiseMaster - Manual (Page 22)

08/20/2004 4001-102-00I
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
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 packing 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 visible 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.
VIII. 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.
IX. 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.
X. LOW RPM OPERATION
At idle, under a no load condition, it is common for GPH readings to fluctuate slightly. These fluctuations are caused by the engine
governor regulating fuel flow to maintain a steady engine RPM.
This concludes Instrument and Sensor testing. If problems persist, contact FloScan Technical Support.