| Tweet |
Custom Search
|
|
|
||
 TM 55-1905-217-34
WARNING
The injector must always be in proper position in relation to the spray deflector before it
is tested, in order to prevent the fuel spray from penetrating the skin. Fuel entering a
persons blood stream may cause serious infection.
(b) Connect the fuel injector to fuel line by rotating inlet clamp handle to move fuel inlet socket against the fuel
injector inlet filler cap. Purge injector of air by stroking the operating handle until clear fuel flows from the outlet cap.
(c) Connect the outlet line to fuel injector by rotating outlet clamp handle to seal socket against fuel injector outlet
filter cap. Operate the tester to build up slight pressure in system and stroke the popping handle two or three times.
(d) With the injector rack in FULL FUEL position, pump handle of test fixture with smooth even strokes. Check
fixture gage and record the injector valve opening (pop) pressure, indicated with the injector sprays fuel. The pop pressure
should be 450 to 850 pounds per square inch. If the pop pressure does not fall within the above range, repair or replace
the injector.
(3) Valve holding pressure test.
(a) Operate the pump handle (fig. 3-6) to bring the fuel injector pressure up to a point just below the injector pop
pressure (450 psi).
(b) Close the fuel shutoff valve and note the pressure drop. The time for a pressure drop from 450 pounds per
square inch to 250 pounds per square inch should not be less than 40 seconds.
(c) If the injector pressure drops from 450 pounds per square inch to 250 pounds per square inch in less than 40
seconds, perform the following:
1. Thoroughly dry the injector with compressed air. Open the test fixture fuel valve and operate the pump handle
to maintain the testing pressure of 450 pounds per square inch.
2. Observe for leaks at the injector rack opening. If this occurs a poor bushing to body fit is indicated.
3. A leak around the spray tip or seal ring usually is caused by a loose injector nut, damaged seal ring or a
hardened surface on the injector nut or spray tip.
4. A leak at filter cap indicates loose filter cap or damaged filter cap gasket.
5. A "dribble" at the spray tip orifices indicates a leaky valve assembly due to damaged surface or dirt. Leakage
at this tip will cause pre-ignition in the engine.
NOTE
A drop or two of fuel at the spray tip is only an indication of the fuel trapped in the
spray tip at the beginning of the test and is not detrimental as long as the pressure
drop specified (para (c) above) is not less than 40 seconds.
(4) High pressure test.
(a) The high pressure test is necessary to detect any fuel leaks at the injector filter caps, body plugs, nut seal ring
and internal lapped surfaces which did not appear during the valve holding pressure test (para (3) above). It also indicates
whether or not the plunger and bushing clearances are satisfactory.
(b) Thoroughly dry the injector with compressed air. Check all fuel connections for leaks and tighten if
necessary. If leaks have occurred, dry the injector again.
(c) With the injector rack in FULL FUEL position and the popping handle locked in position by means of a handle
lock (fig. 3-7) stroke pump operating handle to build up and maintain pressure.
3-8
|
||
|
||
