E N G IN E FUEL
6 M - 4 3
ROCHESTER CARBURETOR DIAGNOSIS
MODELS M , M V - 2 G , 2 G V - 4 M , 4 M V .
NOTE: These problems can be caused by many things other than carburetor. Check the follow ing engine tune-up items
before proceeding w ith carburetor items.
Engine compression, spark plugs, ignition point gap and condition, ignition tim ing, fuel pump pressure and volume,
plugged fuel filters or fuel lines and intake manifold for vacumn ieaks. Make sure all emission control parts are installed and
operating properly. This includes all emission systems solenoids and hoses where used.
Problems o f roughness slight hesitation, surge or poor fuel economy should not be diagnosed before an allowable engine
break in period.
_____________________________________________________________________________
ALL MODELS M , M V - SINGLE BARREL
Problem:
E N G I N E C R A N K S ( T U R N S O V E R ) W I L L N O T S T A R T O R S T A R T S H A R D W H E N C O L D .
POSSIBLE CAUSE
Improper starting procedure used.
Check w ith the customer to determine if proper starting
procedure is used, as outlined in the owner's manual.
No fuel in gas tank
Add fuel. Check fuel gauge for prosper operation.
Choke valve not closing sufficiently when cold.
Adjust the choke thermostatic coil. Use procedure H or I.
Choke valve or linkage binding or sticking.
Realign the choke valve or linkage as necessary. If caused
by d irt and gum, clean w ith automatic choke cleaner.
Do not oil choke linkage.
If parts are replaced, check
adjustments using procedure D, E or F.
No fuel in carburetor.
1. Remove fuel line at carburetor. Connect hose to fuel
line and run into metal container.
Remove the high
tension coil wire from center tower on distributor cap
and ground.
Crank over engine — if there is no fuel
discharge from the fuel line, check fo r kinked or bent
lines. Disconnect fuel line at tank and blow out w ith
air hose, reconnect line and check again for fuel dis
charge.
If none, replace fuel pump.
Check pump for
adequate flow, as outlined in service manual.
2. If fuel supply is o.k., check the following:
a. Inspect fuel filters. If plugged replace.
b. If filters are o.k., remove air horn and check fo r a
bind in the float mechanism or a sticking float
needle. If o.k., adjust float as specified. Use proce
dure A.
Engine Flooded.
NOTE:
To check for flooding, remove the air cleaner,
w ith the engine off, and look into the carburetor bores.
Fuel w ill be dripping o ff nozzles and/or the carburetor
w ill be very wet.
Check to determine if customer is using proper carbu
retor unloading procedure. Depress the accelerator to
the floor and check the carburetor to determine if the
choke valve is opening. If not, adjust the th ro ttle link
age and unloader, as specified. Use procedure G.
Carburetor flooding
NOTE:
Before removing the carburetor air horn, use the
follow ing procedure which may eliminate the flooding.
1. Remove the fuel line at the carburetor and plug. Crank
and run the engine until the fuel bowl runs dry. Turn
o ff the engine and connect fuel line. Then re-start and
run engine. This w ill usually flush d irt past the carbu
retor float needle and seat.
2. If d irt is in fuel system, clean the system and replace
fuel filters as necessary.
If excessive d irt is found, re
move the carburetor unit. Disassemble and clean.
1
LIGHT DUTY TRUCK SERVICE MANUAL
Summary of Contents for Light Duty Truck 1973
Page 1: ......
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Page 53: ...HEATER AND AIR CONDITIONING 1A 27 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 115: ...LIGHT DUTY TRUCK SERVICE M A N U A L HEATER AND AIR CONDITIONING 1A 89...
Page 123: ...BODY 1B 3 Fig 6 Typical 06 Van LIGHT DUTY TRUCK SERVICE MANUAL...
Page 149: ...BODY 1B 29 Fig 84 Body Mounting 06 Fig 85 Body Mounting 14 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 171: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 2 Frame Horizontal Checking Typical FRAME 2 3...
Page 173: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 4 10 30 Series Truck Frame FRAME 2 5...
Page 174: ...2 6 FRAME LIGHT DUTY TRUCK SERVICE MANUAL Fig 5 Underbody Reference Points G Van...
Page 185: ...FRONT SUSPENSION 3 11 Fig 16 Toe out on Turns LIGHT DUTY TRUCK SERVICE MANUAL...
Page 224: ......
Page 266: ......
Page 351: ...ENGINE 6 15 Fig ID Sectional View of Eight Cylinder Engine LIGHT DUTY TRUCK SERVICE MANUAL...
Page 375: ...EN G IN E 6 39 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 376: ...6 4 0 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Page 377: ...ENG IN E 6 41 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 378: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 37L K Series Engine Front Mount 6 42 ENG INE...
Page 400: ...6 6 4 ENG INE LIGHT DUTY TRUCK SERVICE MANUAL...
Page 401: ...ENG IN E 6 65 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 402: ...6 6 6 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Page 403: ...E NG IN E 6 67 Fig 36V C Series Engine Mounts LIGHT DUTY TRUCK SERVICE MANUAL...
Page 410: ......
Page 423: ...EN G IN E C OOLING 6K 13 Fig 16 Overheating Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Page 424: ...6 K 1 4 ENG INE COOLING Fig 17 Coolant Loss Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Page 456: ...6M 32 ENGINE FUEL Fig K15 Accelerator Controls G Van L 6 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 492: ......
Page 512: ...Fig 18e Vacuum Advance Diagram V8 Engine...
Page 516: ...6 T 2 4 E M IS S IO N CONTROL SYSTEMS LIGHT DUTY TRUCK SERVICE MANUAL...
Page 528: ......
Page 590: ......
Page 593: ...CLUTCHES MANUAL TRANSMISSIONS 7M 3 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 598: ...7M 8 CLUTCHES MANUAL TRANSMISSIONS LIGHT DUTY TRUCK SERVICE MANUAL...
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Page 654: ......
Page 743: ...FUEL TANKS AND EXHAUST 8 13 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 744: ...8 14 FUEL TANKS AND EXHAUST LIGHT DUTY TRUCK SERVICE MANUAL...
Page 760: ...8 30 FUEL TANKS AND EXHAUST Fig 40 Exhaust Pipe P Models LIGHT DUTY TRUCK SERVICE MANUAL...
Page 761: ...FUEL TANKS AND EXHAUST 8 31 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 763: ...FUEL TANKS AND EXHAUST 8 33 LIGHT DUTY TRUCK SERVICE MANUAL...
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Page 832: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 106 Power Steering Pump Mounting Typical 9 66 STEERING...
Page 833: ...PUMP ASSEMBLY STEERING GEAR TYPICAL SMALL V8 TYPICAL LARGE V8 STEERING 9 67...
Page 861: ...STEERING 9 95 Fig 134 Power Steering Pump Leakage LIGHT DUTY TRUCK SERVICE MANUAL...
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Page 876: ......
Page 886: ...11 10 CHASSIS SHEET METAL LIGHT DUTY TRUCK SERVICE MANUAL...
Page 891: ...ELECTRICAL BODY AND CHASSIS 12 5 LIGHT DUTY TRUCK SERVICE MANUAL...
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