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 MANUALSGMC1983VALUE VAN P2500, 6.2 J, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMCARBURETOR - ROCHESTER E4ME 4-BBLADJUSTMENTSSECONDARY (REAR) VACUUM BREAK
1983 GMC Value Van P2500, 6.2 J, Standard
Secondary (Rear) Vacuum Break
1983 GMC Value Van P2500, 6.2 J, StandardSECTION Secondary (Rear) Vacuum Break
NOTE:
Choke coil lever and choke rod (fast idle cam) adjustments must be correct before performing this adjustment. Adjustment is performed with choke valve angle gauge. See procedure at beginning of Adjustments. DO NOT
remove rivets and choke cover to perform this adjustment.
- Attach rubber band to Green tang of intermediate choke shaft. Open throttle to allow choke valve to close. Set up angle gauge.
- Using an outside vacuum source of at least 18 in. Hg, seat secondary (rear) vacuum break diaphragm. If air valve rod restricts vacuum break plunger from being seated, bend rod to allow full plunger travel. Be sure leaf bucking spring is compressed, if equipped. See Fig 1.NOTE: On models equipped with air bleed, remove rubber cover from filter and plug vacuum tube with a piece of tape. If bleed hole is in end of diaphragm, plug hole in end of diaphragm with tape. On delay models with air bleed, plug end cover with an accelerator pump plunger cup. Remove tape or cup after completion of adjustment.
- Close choke by pushing up on choke coil lever or vacuum break lever tang. Hold choke closed with a rubber band.
- Bubble on choke valve angle gauge should be centered with specified degree mark opposite pointer.
- To adjust on models equipped with hex adjustment, use a 1/8" hex wrench to turn adjustment screw in rear cover of vacuum break with vacuum still applied.
- To adjust on models without hex adjustment, support rod at "S" and bend vacuum break rod with vacuum still applied. Adjustment is correct when bubble of choke valve angle gauge is centered.
RENDER: 1.0x
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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.