Tune-Up - 4.9l 6-cyl Ford Cab & Chassis Ranger

ENGINE IDENTIFICATION

Engine can be identified by the eighth character of the Vehicle Identification Number. Number is located on Safety Compliance label on left front door pillar. It also is located on metal plate, riveted to the driver's side of dash and visible through windshield.

VIN ENGINE CODE

TUNE-UP NOTES

Note. When performing tune-up procedures described in this article, the following notes and precautions must be followed

1. For tune-up purposes, "Light Duty" refers to vehicles up to 8500 lbs. GVW. "Heavy Duty" refers to vehicles exceeding 8500 lbs. GVW.
2. Due to late changes and corrections, always refer to Engine Tune-Up Decal in engine compartment before attempting tune-up. If manual and decal differ, always use specifications on Engine Tune-Up Decal.
3. Do not allow or create a condition of engine misfire in one or more cylinders for an extended time. Damage to converter may occur due to loading converter with unburned air/fuel mixture.
4. If Dura-Spark 2-piece distributor cap must be removed, first remove top portion, then rotor, then bottom portion (adapter). If any spark plug wire is disconnected with this system, connection must be first greased with silicone grease before it is reattached.
5. When connecting a tachometer to Dura-Spark ignition coil, install the alligator clip on tachometer into the "DEC" (Tach Testing) cavity.

ENGINE COMPRESSION

Test compression with spark plugs removed, engine at normal operating temperature and throttle wide open. Crank engine through at least 5 compression strokes before recording reading.

COMPRESSION SPECIFICATIONS

FUEL PUMP

Check fuel pump at idle RPM with engine at normal operating temperature.

FUEL PUMP SPECIFICATIONS

SPARK PLUGS

SPARK PLUG TYPE

SPARK PLUG SPECIFICATIONS

HIGH TENSION WIRE RESISTANCE

1. Loosen wires from spark plugs by twisting spark plug boot carefully to loosen seal on spark plug. Remove wires by pulling on plug boot. Remove distributor cap from distributor, leaving wires connected to cap.
2. Using an ohmmeter, check resistance of each wire. Connect one ohmmeter lead to coil wire or spark plug wire terminal and other lead to distributor cap insert.
3. Replace any wire with over 5000 ohms resistance per INCH. New wires should have a resistance of 7000 ohms per FOOT.

HIGH TENSION WIRE RESISTANCE (OHMS)

Note. Whenever a high tension wire is disconnected, spark plug terminal boot interior must be coated with dielectric silicone grease before reconnecting.

VALVE ARRANGEMENT

E-I-E-I-E-I-E-I-E-I-E-I (Front-to-rear).

VALVE CLEARANCE

VALVE CLEARANCE SPECIFICATIONS

DISTRIBUTOR

All Light Duty models are equipped with TFI-IV (Thick Film Integrated) ignition system. All Heavy Duty models are equipped with Dura-Spark II ignition system. No adjustments are required.

Timing Mark & Firing Order (Receptacle For Magnetic Pick-Up Timing Light Is Located At 135° ATDC). Scheme 7

IGNITION TIMING

1. Place transmission in Neutral (man. trans.) or "P" (auto. trans.). Turn A/C and heater off. Remove vacuum hose from distributor vacuum advance connection, and plug hose.
2. Place mark on proper degree line of damper (or of pointer and damper notch). Connect timing light using inductive pick-up or adapter. Do not puncture spark plug leads.
3. Connect an accurate tachometer. On EEC-IV equipped models, disconnect single Black lead connector near distributor. Start engine and warm engine to normal operating temperature. With engine idling in Neutral, check timing.
4. If timing is not correct, loosen distributor hold-down bolt and rotate distributor to set timing. Recheck after tightening bolt.

IGNITION TIMING SPECIFICATIONS (Degrees BTDC @ RPM)

Light Duty

1. Place transmission in Neutral (man. trans.) or "D" (auto. trans.) with engine to normal operating temperature. Turn off all accessories. Remove air cleaner. Disconnect and plug vacuum line at bottom of air cleaner. Allow engine speed to stabilize and measure curb idle speed.
2. With engine off, disconnect Engine Coolant Temperature (ECT) sensor connector. Start engine and open throttle momentarily 3 times. Adjust the maximum Idle Speed Control (ISC) extension screw. (Scheme 8)
3. Place transmission in Neutral. Reconnect ECT sensor wire connector. Increase RPM momentarily. Allow ISC to adjust idle speed, then recheck idle RPM.
4. Turn engine off. Connect a jumper wire between STI connector and single pin return pin on self-test input connector. (Scheme 9) Turn ignition key to run position, but do not start engine. Allow ISC motor to retract.
5. Disconnect jumper wire and ISC motor connector. Start engine. Check anti-diesel RPM with ISC off. If necessary, adjust anti-diesel RPM to 500-550 RPM. If the idle speed or ISC motor does not operate correctly, see the EEC-IV article in the EXHAUST EMISSION SECTION.

Adjustment Points For YFA 1-Bbl. Carburetor On Light Duty Engines (Use Allen Wrench To Adjust Idle Speeds). Scheme 8

Jumper STI & Self-Test Connectors. Scheme 9

LIGHT DUTY IDLE SPEED (RPM)

Heavy Duty

1. Place transmission in Neutral (man. trans.) or "P" (auto trans.) with engine at normal operating temperature. Turn A/C heat selector off.
2. Turn engine on to activate Throttle Speed Positioner (TSP). Set curb idle to specification by turning solenoid in or out. (Scheme 10)
3. With transmission selector in Neutral (man. trans.) or "P" (auto. trans.), increase engine speed momentarily, letting it return to normal curb idle. Check RPM and readjust if necessary.
4. If final curb idle speed adjustment is required, bowl vent setting must be checked. Stop engine and turn ignition key "ON". Secure choke plate in wide open position.
5. Open throttle so that throttle vent lever does not touch fuel bowl vent rod. Close throttle and measure travel of fuel bowl vent rod at point "A" from open position. (Scheme 11)
6. Travel should be within.10-.15" (2.5-3.8 mm). If out of specification, bend vent lever to obtain required travel. To set TSP-Off RPM, run engine to normal operating temperature. Turn A/C heat selector to "OFF". Disconnect TSP wire. Place transmission in Neutral. Using TSP-Off adjusting screw, set TSP-Off RPM to specifications. Reconnect TSP wire to terminal.

Adjustment Points For YFA 1-Bbl. Carburetor On Heavy Duty Engines (A/C Heat Selector Must Be "OFF"). Scheme 10

Setting Fuel Bowl Vent. Scheme 11

HEAVY DUTY IDLE SPEED (RPM)

IDLE MIXTURE ADJUSTMENT

Note. This procedure is not part of normal tune-up procedure. Idle mixture should be adjusted only during carburetor repair or when necessary as a result of government inspection laws.

Mixture Screw Cap Removal

1. Remove carburetor from engine. Drain fuel from carburetor. Using a hacksaw, carefully cut a lengthwise slot through metal cup around mixture screw. Do not cut throttle body.
2. Insert a screwdriver into hacksaw slot and twist screwdriver to spread cap. Spread cap just enough to remove inner cap. Count number of turns needed to lightly seat mixture screw needle. Remove mixture screw and cup.
3. When adjustment is complete, install idle mixture screw and spring. Install new tamper-resistant cup. Turn screw in until it lightly seats. Turn screw out same number of turns noted during disassembly. Reinstall carburetor in engine.

Note. Propane enrichment procedure is for Light Duty Vehicles only.

Propane Enrichment Procedure

1. Leave all vacuum signal hoses attached to air cleaner assembly when relocating air cleaner for carburetor adjustments. Air cleaner must be installed for engine speed checks.
2. Apply parking brake and block wheels. Disconnect automatic brake release, and plug vacuum connection, if equipped. Connect tachometer.
3. Disconnect and plug fuel evaporative purge valve signal hose at engine. Disconnect purge hose at air cleaner and plug nipple.
4. Disconnect flexible fresh air tube from air cleaner duct or adapter. Insert hose from propane enrichment tool (Rotunda T75L 9600 A) about 3/4 of the way into duct or fresh air tube. Disconnect PCV valve from grommet, and allow valve to draw underhood air during adjustment.
5. For vehicles equipped with thermactor, disconnect and plug hoses of dump valves equipped with 2 fittings. If valves have one fitting, remove and plug hose at valve. Connect slave hose to dump valve and intake manifold vacuum source.
6. Verify ignition timing is set to specification and adjust if necessary. With engine at normal operating temperature, check curb idle speed or A/C-Off RPM. Adjust as necessary. Run engine at 2500 RPM for 15 seconds before each mixture check.
7. With engine idling in Neutral, gradually open propane tool valve and watch for engine speed gain on tachometer. When speed reaches maximum and begins to drop off, note amount of speed gain. NOTE: Propane cartridge must be in vertical position. If engine speed will not drop off, check bottle gas supply. If necessary, repeat test with new bottle.
8. Compare measured speed gain with specifications. If mixture adjustment is necessary, adjust so gain is within "Reset RPM" specifications. If propane enrichment speed gain is within "RPM Gain" specifications, proceed to step 11).
9. If measured speed gain is greater than specification, turn mixture screw counterclockwise, and recheck until measured speed rise is within "Reset RPM" specifications. Proceed to step 11).
10. If measured speed gain is less than specification, turn mixture screw clockwise, and recheck until measured speed rise is within "Reset RPM" specifications. Proceed to step 11).
11. Check curb idle, and remove all test equipment. Reconnect hoses in original positions, and connect PCV valve.

PROPANE MIXTURE ADJUSTMENT (RPM)

1. Place transmission in Neutral (man. trans.) or "P" (auto. trans.). Bring engine to normal operating temperature. Disconnect vacuum hoses at EGR, purge valve or purge solenoid valve, and plug hoses.
2. Disconnect and plug vacuum hose from cold start vacuum switch (Orange vacuum switch on valve cover). Using a slave vacuum hose, connect manifold vacuum to cold start vacuum switch.
3. Place fast idle screw on 2nd step (kickdown) of fast idle cam. Adjust fast idle speed to specifications. (Scheme 8) Remove plugs from vacuum hoses, and restore all hoses to their original locations.

LIGHT DUTY FAST IDLE SPEED (RPM)

AUTOMATIC CHOKE

Note. Some models may have tamper-proof choke assemblies.

Drill heads from 2 rivets, and remove. Loosen retaining screw, and turn choke cover in direction indicated on cover to specified setting. Install new rivets and tighten screw.

AUTOMATIC CHOKE SPECIFICATIONS

All Light Duty models are equipped with TFI-IV (Thick Film Integrated) ignition system. All Heavy Duty models are equipped with Dura-Spark II Ignition system. Both systems required no outside adjustments.

DISTRIBUTOR PICK-UP COIL RESISTANCE

TOTAL SPARK ADVANCE @ 2500 RPM

IGNITION COIL

IGNITION COIL RESISTANCE - OHMS @ 75°F (24°C)

FUEL SYSTEMS

CARBURETORS

BATTERY

BATTERY SPECIFICATIONS

STARTER

All models use Motor craft positive engagement type starters with either a 4" or 4 1/2" armature.

STARTER SPECIFICATIONS

ALTERNATOR

All models use Motorcraft alternators.

ALTERNATOR SPECIFICATIONS

ALTERNATOR REGULATOR

Two models of Motorcraft electronic voltage regulators are used. Although they look alike, they are not interchangeable.

REGULATOR IDENTIFICATION

BELT ADJUSTMENT

BELT ADJUSTMENT (TENSION IN LBS. (KG) USING STRAND TENSION GAUGE)

SERVICE INTERVALS

REPLACEMENT INTERVALS

CAPACITIES

FLUID CAPACITIES (EXCEPT FUEL & COOLING)

FUEL TANK CAPACITIES

COOLING CAPACITIES

SYSTEM REFRIGERANT CAPACITIES