My `77 had been running superbly. Then suddenly yesterday she started running rough and within ten minutes would not take throttle at all.
She starts and idles roughly, but that's it.
I changed the two fuel filters. No change. (Heard there is a 3rd for return but don't know where it is)
She has fuel flow to the carb.
Tried pulling out the spark wires one by one to see if there was a single bad cylinder. Made little difference. At one point I had two out and she still had the identical rough idle!
Any thoughts where/what I, a non-mechanic, can check? Any and all help will be appreciated!
-Don
Italian motorcycles. An Italian car. An Italian wife. What more could a man desire?
Did you check for spark at the coil, at the plug wires, at the plugs? Perhaps the point gap or condition of the points is questionable. Same comment for cap, rotor. Condensor could be bad. Coil maybe? If the key electrical parts haven't been replaced in a while, I change them all out (points, condensor, cap, rotor, plug wires, plugs). You could selectively change them out one at a time to find the main problem (assuming that the problem is electrical), but I'd refresh everything if it were me.
If everything electrical looks good (spark at coil, at wires, at plugs), I'd suspect carburetion issues as the next culprit. Float level? Plugged jets?
if you pulled 2 plug wires and made no difference, then those cyls aren't firing. If they are side by side, you could have a vacuum leak or blown head gasket. If they are side by side in the firing order you could have a cracked dist cap. Ace's suggestion to check the point gap is a good one
If you pulled two wires and no change, you need to check into that. You obviously have spark from the coil of would not run. By same token, points are probably OK, or it would not run. No reason to change all the parts, find the culprit and fix it.
Just pulling plug wire off is NOT a good way to kill cylinders. The spark, thousands of volts, is still gonna go somewhere, which means it often finds it's way to the next cylinder in the dist cap or into the rest of the iignition primary. Simple way to kill cylinders, get some fine wire (speaker wire etc) , and put small hunks (2") into the dist cap under each spark plug wire boot, with an end hanging out. Now when you want to kill a cylinder, simply short a grounded piece of wire to the wire sticking out of that cylinders wire at the cap. Just takes a few minutes to rig up.
Rull coil wire and ground it so no sparky. Then crank engine and listen to rythm. A good engine will have a nice rythmetic sound....RRRRRRRRRRRRRRRRRRRRRRRRRRRR and engine with compression issues will go RRRuhRRRuhRRRuhRRRuh or worse. Takes but a few seconds. OR, you can check compression.
If indeed you have two cylinders that do not make a diff when shorted, now pull those two wires off plugs and put other plugs in wires and lay on engine. Start car. If plugs are firing nothing wrong with ignition.
Now you need to start looking for vacuum leaks or carb issue. With engine running and air cleaner off, put hand slowly over carb and see if running improves.
All this takes but a few minutess and costs nothing. Or you can support your local parts store.
Keith
