TM 55-1930-209-14&P-21
(3)
Valve Holding Pressure Test. This test determines if body-to-bushing mating surfaces in injector are
sealing properly and indicates proper plunger- to-bushing fit.
(a)
Clamp injector properly and purge air from system.
(b)
Close thru-flow valve, but do not overtighten.
(c)
Move lever 2 to rear, horizontal position.
(d)
Operate pump lever 1 until gage 1 reads approximately 500 psi.
(e)
Move lever 4 to UP position.
(f)
Time pressure drop between 450 to 250 psi. If pressure drop occurs In less than 15 seconds,
leakage is excessive.
(4)
High Pressure Test. This test checks for leaks at Injector filter cap gaskets, body plugs, and nut seal
ring.
(a)
Clamp injector properly and purge air from system.
(b)
Close thru-flow valve, but do not overtighten.
CAUTION
Be sure lever 4 is down position before operating pump lever 1.
(c)
Move lever 2 to forward, horizontal position.
(d)
Operate pump lever 1 to build up to 1600-2000 psi on gage 1 and check for leakage at filter cap
gaskets, body plugs, and nut seal ring.
(5)
Spray Pattern Test. This test determines spray pattern uniformity and relative pressure at which
injector valve opens and fuel injection begins.
(a)
Clamp injector properly and purge air from system.
(b)
Close thru-flow valve to allow pressure to build In gage 1.
CAUTION
Do not overtighten or nut on seal will be damaged.
(c)
With fuel rack in FULL FUEL position, operate pump lever 1 rapidly until valve opening pressure
of 450 to 850 psi is reached and spray pattern occurs.
(6)
Visual Inspection of Plunger. An injector which passes test must have plunger checked visually, under
a magnifying glass, for excessive wear or for a possible chip in bottom helix. There is a small area on bottom helix and
lower portion of upper helix that, If chipped, will not be indicated in any of tests.
(7)
Fuel Output Test
(a)
When injectors are removed from an engine for output testing, and If satisfactory, reinstalled
without disassembly, extreme care must be taken to avoid reversing fuel flow. When fuel flow is reversed, dirt trapped
by filter is back-flushed Into Injector components.
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