GMC 1976 ZEO 6083 Maintenance Manual page 354

6M- 12
ENGINE FUEL SYSTEM
ENGINE STARTS HARD WHEN HOT
ENGINE RUNS UNEVEN OR SURGES .
Possible Cause
Corrective Action
Float level too low.
Check and reset float level .
Float not dropping far enough in
Check for bind in float hanger and float arm,
bowl .
float alignment in bowl and needle pull clip for
sufficient clearance on float arm .
Main metering jets or metering
1 . If the main metering jets are plugged or dirty
rods dirty, plugged or incorrect
or excessive dirt is in fuel bowl, the carburetor
part .
should be completely disassembled and cleaned.
2. If the jets or rods are incorrect size, consult
the parts list for proper usage. The last two
digits stamped on the primary rods and jets are
the last two digits of the part number.
Possible Cause
Corrective Action
Choke valve not opening com-
1 . Check for binding choke valve and/or linkage.
pletely .
Clean and/or replace as necessary.
Do not oil choke linkage.
2. Check and adjust choke thermostatic coil .
Engine flooded, carburetor
See procedure under "Engine cranks, will not
flooding .
start engine flooded."
No fuel in carburetor .
1 . Check fuel pump . Run pressure and volume test .
2. Check float needle for sticking in seat, or
binding float.
3. Check and adjust float level.
Leaking float bowl .
Fill bowl with fuel and look for leaks.
- Possible Cause
Corrective Action
Fuel restriction .
Check all hoses and fuel lines for bends, kinks
or leaks. Straighten and secure in position .
Check all fuel filters, if plugged or dirty -
replace.
Dirt or water in fuel system .
Clean fuel tank, lines and filters.
Remove and clean carburetor .
Fuel level.
Adjust float.
Check for free float and float needle valve opera-
tion . Free up or replace as necessary.
Metering rods bent or incorrect
Clean or replace as necessary.
part . Main metering jets dirty,
defective, loose or incorrect part