Z-drive Posted January 14, 2009 Share Posted January 14, 2009 I have a 280 with a 3.1L stroker and triple mikuni's. It started misfiring about two days ago on my way home from work. When i get into higher rpm's, it will stop missing for a few seconds and start again. to me this sounds like my carbs are way out of sync ,. does anyone else agree? my spark plugs look good, fuel filter is clean, distributor looks great. thanks in advance for any info. Quote Link to comment Share on other sites More sharing options...
sorealsosurreal Posted February 9, 2009 Share Posted February 9, 2009 hows the timing, and or intake manifold gasket. otherwise id say your right on the carbs. Quote Link to comment Share on other sites More sharing options...
Lazeum Posted February 9, 2009 Share Posted February 9, 2009 If missfiring happens when trottle is opened, I would believe issue is not coming from carb sync (it does not mean sync is ok though) I would check timing as suggested by sorealsosurreal, distributor might have moved. I would also agree you might have an air leak somewhere. I believe you would also experience idle issue if leak is big enough to create missfire at high rpm. A fuel line sticked to your ear you help you to spot the leak. Have you checked fuel pressure, it could also be a bad fuel pump or a bad regulator if you have one. Do you notice any smell or smoke? Any detonation noise or loss of power? Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted February 9, 2009 Share Posted February 9, 2009 Could be spark leads breaking down (crossfire) too. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted February 9, 2009 Share Posted February 9, 2009 When i get into higher rpm's, it will stop missing for a few seconds and start again. to me this sounds like my carbs are way out of sync ,. does anyone else agree? From what you write, it sounds like the misfiring is intermittent? I doubt out of sync carbs would give you an intermittent misfire. Also, from your comments, it sounds like this problem came on suddenly? I'd put my focus on the ignition system and make sure it's not the culprit before I went after the carbs themselves. BTW, if you are sure the ignition is ok, how about the electric fuel pump, filter back by the tank, and condition of the tank itself? Could any of those things be causing problems with fuel getting to the carbs? My own experience with triples was with webers, but once set, they were pretty reliable. I imagine mikunis are about the same. Unless you see something obviously wrong with them, as I said above, I wouldn't start tearing into the carbs until I had eliminated the easier stuff. Quote Link to comment Share on other sites More sharing options...
capt_furious Posted February 13, 2009 Share Posted February 13, 2009 Check your plugs. I had mine start giving me hell last week, new plugs cleaned it right up. While you're at it, check the wires, cap, rotor, and slop / play in the distributor shaft. Low fuel pressure could also be a culprit. Check your filters. Quote Link to comment Share on other sites More sharing options...
Z-drive Posted February 19, 2009 Author Share Posted February 19, 2009 well my fuel tank is a bit rusty,. i change my filter every month or so. I have an electric fuel pump, pressure regulator set to 4 psi. i don't believe my problem is electrical. I had no idea there is a filter back by the tank. ill have to check that out,.. maybe replace the pump. I cleaned the jets on the carbs,. no change. i wish i knew what was going on. it really doesn't slow the car down much. it actually runs better when i am on the gas. higher rpms are no problem as long as i am accelerating. but anything id say, under 3500 rpm will misfire. unless im maintaiing a speed. Quote Link to comment Share on other sites More sharing options...
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