GMC T Series 1994 Repair Manual page 347

Valve. If the valve is stuck, soak the pump
housing in carburetor cleaning solvent.
Inspect
• For foreign material, if found, determine the
source.
^ Clean
• All parts of sludge, oil and varnish.
• Varnish may be removed by soaking in carburetor
or cleaning solvent.
CAUTION: Avoid breathing of fumes,
or exposure of the skin to the
cleaning solvent, as bodily injury may
result.
Pump housing and cover for:
- Cracks.
- Scoring.
- Casting imperfections.
- Damaged threads.
- Do not attempt to repair the pump housing.
- If in doubt, replace the housing.
Pressure regulator valve for:
- Scoring.
- Sticking.
- Burrs, may be removed with a fine oil stone.
Pressure regulator valve spring for:
- Loss of tension.
- Bending.
- If in doubt, replace the spring.
Suction pipe and screen assembly for:
- Looseness.
- If the pipe is loose or has been removed, the
pump cover and pickup tube must be replaced.
- Broken wire mesh or screen.
Gears for:
- Chipping.
- Galling.
- Wear.
Measure
m
• Refer to " Oil Pump Specifications" in this
section.
• Gear lash. Install gears and measure in several
places, refer to Figure 41.
• Pump housing gear pocket, refer to Figure 42.
• Gears, refer to Figure 43.
• Gear side clearance, refer to Figure 44.
• Gear end clearance, refer to Figure 45.
[T ] Important
• When deciding pump serviceability based on end
clearance, consider depth of wear pattern in the
pump cover.