Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1982SUBURBAN K2500, 5.7L ENG VIN M, STANDARD TRANSREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE MECHANICALFUEL SYSTEMROCHESTER MODELS M4MC & M4ME 4-BARRELADJUSTMENTSECONDARY VACUUM BREAK
1982 GMC Suburban K2500, 5.7L Eng VIN M, Standard Trans
Secondary Vacuum Break
1982 GMC Suburban K2500, 5.7L Eng VIN M, Standard TransSECTION Secondary Vacuum Break
NOTE:
Choke coil lever adjustment must be correct before performing this adjustment. This adjustment is performed using the choke angle gauge, see procedure at beginning of Adjustment.
- Using an outside vacuum source of at least 15 in. Hg, seat secondary vacuum break diaphragm. Plug purge bleed hole (if equipped) with masking tape. Hole is found in end of diaphragm.
- On vacuum delay models with air bleed, plug end cover with an accelerator pump plunger cap (2G carburetor type). Remove pump plunger cap after adjustment.
- Air valve rod must not keep vacuum unit from fully retracting. If necessary, bend air valve rod at air valve lever to provide clearance for proper adjustment. Adjust final air rod clearance after setting secondary vacuum break adjustment.
- Lightly close choke valve by pushing up on choke coil lever or vacuum break lever tang. Hold in position with a rubber band. Make sure bucking spring on diaphragm plunger (if equipped) is compressed and seated. Bubble on choke valve angle gauge should be centered with specified degree mark opposite pointer. See Fig 1.
Lightly hold choke in closed position.
- To adjust, turn screw at end of vacuum diaphragm until bubble in angle gauge is centered. Remove gauge.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.