Fuel Systems

Appendix A — Fuel System Standard

15.0 — Lab Examination No. 11
Fuel System Static Pressure Test cont'd

15.5 Test

15.5.1 This procedure shall be used to perform a pressure test of the fuel system after the entire system has been installed in a boat. It is in addition to any pre-installation component leak tests that may have already been accomplished.

15.5.2 Visually inspect the entire fuel system up to and including the inlet fitting in the carburetor.

Known discrepancies, which may be corrected without invalidating the test, should be completed at this time. Verify that the system has been at a reasonably constant ambient temperature for two hours prior to the start of the test and will remain so during the performance of the test. To accomplish this, it is highly desirable, although not mandatory, for the system to be in a controlled atmosphere, such as in a building, rather than outside where the temperature may vary quite rapidly depending on the time of day, sunshine, etc.

Note:
When accomplishing the following test, it is highly desirable to break into the fuel system in as few places as possible. It is recognized, however, that due to the location or a particular type of fill and vent fitting used, it may be impossible or unreasonably difficult to test the system without breaking the system at the upper end of the fill and/or vent hoses. Therefore, the test has been written with the assumption that these hoses have been disconnected at the boat connect end (not at the fuel tank end). If for a particular boat or installation the test can reasonably be accomplished without breaking the system at one or both of these points, the test should be run in the same manner.

15.5.3 Disconnect the fuel feed line at the engine fuel inlet, engine installed fuel pump or filter and install a pressure gauge or a suitable manometer.

15.5.4 Disconnect the fuel tank vent line at the deck fitting the plug the vent hose (the preferred method is to plug the external vent fitting).

15.5.5 Disconnect the fuel tank fill line at the deck fitting and connect the pressure supply adapter assembly to the fill hose (the preferred method is to use a modified fill cap for the adapter).

Note:
If it is more convenient to connect the pressure supply adapter assembly to the vent line and plug the fill line, it is permissible to do so.

15.5.6 If an auxiliary fuel tank is installed in addition to the main tank, the fill and vent lines on it should be capped or plugged, similar to the main tank, and a pressure gauge installed.

15.5.7 The pressure required for this test shall be the greater of the two pressures as called out below:

a. Three (3) psig
b. One and one-half (1-1/2) times the static head pressure as determined in this manner:
measure the vertical height (H) in inches from the lowest point in the fuel system to the top of the fill or the vent line, whichever is lower. If the calculated pressure (0.04 x H in.) is greater than the tank labeled pressure, stop the test. If H is 75 in. (1.9 m) or less, use 3-psig for the test pressure as called out in part (a) above and record this pressure on Data Form No. 2, Part A-3. If H is greater than 75 in. (1.9 m), the test pressure shall equal 0.04 (H) psig.

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