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HOMESERVICE MANUALSJEEP1986WAGONEER BASE, 2.5 H, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCEADJUSTMENTTUNE-UP - V6ADJUSTMENTSIDLE MIXTURE ADJUSTMENTCALIFORNIA MODELS
1986 Jeep Wagoneer Base, 2.5 H, Standard

California Models

1986 Jeep Wagoneer Base, 2.5 H, StandardSECTION California Models
  1. Modify Carburetor Adjuster (J-29030-B), by grinding off 1/8" from rear and 1/4" from front of adjuster. Remove carburetor from engine, and remove idle mixture screw plug. Turn mixture screw in until lightly seated and back out 4 turns. If plug in air horn (covering idle air bleed) has been removed, replace air horn.
  2. Remove vent stack screen assembly to gain access to lean mixture screw. Turn lean mixture screw until lightly bottomed and back out 2 1/2 turns. Some resistance should be felt. If there is no resistance, remove screw and check for spring.
  3. Install carburetor on engine, with modified Carburetor Adjuster (J-29030-B), installed on mixture adjustment screw. Do not install air cleaner. Disconnect bowl vent line at carburetor. Disconnect EGR valve and canister purge hoses at carburetor. Plug carburetor ports.
  4. Disconnect carburetor-to-temperature sensor hose on air cleaner and plug open hose. Connect a dwell meter lead to the mixture control solenoid dwell test lead (Green connector).
  5. Set dwell meter to 6-cylinder position. Connect a tachometer to distributor lead (Brown connector). Set parking brake and block wheels. Transmission should be in Park (auto. trans.) or Neutral (man. trans.). Start engine and bring to normal operating temperature.
  6. Run engine at 3000 RPM for at least 3 minutes with fast idle screw on high step of cam, and until engine is in closed loop operation. With engine at 3000 RPM, adjust lean mixture screw slowly, allowing time for dwell to stabilize.
  7. It is normal for dwell to vary over a narrow range (approximately 5°). Turn screw to obtain an average dwell of 35°. If unable to adjust, inspect main metering circuit for leaks or restrictions. Return engine to idle.
  8. Adjust idle mixture screw to obtain an average dwell of 25°. Adjustment is very sensitive. Make final check with carburetor adjuster removed. If unable to adjust, inspect idle system for leaks or restrictions. Disconnect mixture control solenoid.
  9. Check for an RPM change of at least 50 RPM. If RPM does not change, check idle air bleed circuit. Run engine at 3000 RPM for a few moments and note dwell reading. Dwell should show an average of 35°. If not, reset lean mixture screw. Then reset idle mixture screw to obtain 25° dwell.
  10. When dwell readings have been set, remove carburetor. Remove mixture adjuster. Seal idle mixture screw access hole with RTV sealant. Reinstall carburetor. Reconnect all hoses and install vent screen and air cleaner. Set idle speed to specification.
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.