1964-1974 [Subscribe to Daily Digest] |
Having better information from you would make it easier to give you some direction here, so I'll ask a few questions then give you some quick tips on misfire diagnosis.
When did this problem start? Did it come on gradually or all at once? Does it occur at idle, under acceleration, at steady speed, always? Hot, cold, both? Have you adjusted the valves? When it happens, describe what happens. "Misfire" takes many forms and has many causes. Misfire from various causes may feel similar or produce very different symptoms.
Misfire on an engine in good mechanical condition (not irrelevant to repeat that part IN GOOD MECHANICAL CONDITION) is usually due to problems with spark or problems with fuel delivery or fuel mixture.
Spark: If you position the distributor cap end of the coil wire 1/2" from a ground point (fasten it in place somehow to avoid shock risk) and watch while someone cranks the engine, and you have a very consistent periodic spark, and new components as indicated, basic ignition is probably OK. Ignition timing still needs to be checked.
Fuel delivery: Remove the air cleaner, prop the throttle plate open, and watch down the carburetor throat with a flashlight while exercising the throttle linkage. A steady stream of fuel from the accelerator pump nozzle each time the throttle is opened suggests that fuel is getting to the carb. A weak erratic dribble may indicate low fuel delivery to the carb, or a failed accelerator pump. Either can cause "misfire."
Fuel mixture: If misfire is present at idle, you can learn some by spraying a short burst of spray carb cleaner into the carb throat. If idle quality improves you may have a fuel mixture problem. Idle mixture adjustment still needs to be checked.
These are very general and basic techniques that may point you in a useful direction. More precise information about how you experience the problem will facilitate more precise help.
posted by 208.53.81...
, Mon, 12 Sep 2005 00:01:34
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
