DIAGNOSIS
POSSIBLE CAUSE
CORRECTION
COMPLAINT: Rough Idle (Cont)
Idle is erratic or insensitive to adjustment.
Loose or damaged idle tubes, clogged air bleeds, and restricted idle fuel passages.
Check and clean idle air bleeds. Remove and clean idle tubes. Inspect idle tubes and replace damaged or distorted idle tubes with authorized Holley replacement parts. Tighten idle tubes securely when installing.
Idle is erratic and unable to adjust properly to low idle speed.
Improper stretched diaphragm.
Remove governor diaphragm cover see "Reassembly" for correct method on installation of diaphragm.
COMPLAINT: Poor Low Speed Operation (off-idle)
Engine idles satisfactorily but falters at low speeds just above idle rpm.
Idle adjusting needles unequally set.
Readjust idle adjusting needles as outlined in "Adjustments" section of this manual. Be sure both needles are set an equal distance off their seats.
Poor low speed performance regardless of idle adjusting needle setting.
Idle transfer holes clogged or damaged.
Remove carburetor. Inspect idle transfer holes visually for cleanliness. Check with wire gage for specified size.
COMPLAINT: Faulty Acceleration
Sluggish engine response. Little or no fuel discharged at pump discharge nozzles upon acceleration.
Inoperative pump inlet check valve.
With airhorn removed, hold finger lightly over pump discharge needle, and pump throttle repeatedly. If inlet check ball does not seat, fuel will bubble back into float chamber from pump inlet passage. Replace pump inlet ball check valve with authorized Holley replacement parts.
Continual discharge from pump discharge nozzles at higher speeds. Economy complaint usually accompanies this.
Inoperative pump discharge needle valve.
Check pump discharge needle and its seat for damage or foreign matter which would prevent needle from seating properly. Replace damaged or worn needle with authorized Holley replacement part. Stake needle as desscribed in "Reassembly" section of this manual.
Weak fuel discharge from pump discharge nozzles upon acceleration. Fuel leaks over top of piston in well when throttle is pumped.
Worn, distorted, or damaged pump piston.
Replace pump piston with authorized Holley replacement part
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