Guest Zpeed Posted July 28, 2001 Share Posted July 28, 2001 last week it was running pefect, noww.. is a different story, once it hits about 2000rpm.. it pops, the engine has no power, i'm suspecting its got something to do with the SU's, but i'm not sure i've checked the alternator, all electrics seem fine, when i have the choke on its completly fine, so i think its a full problem, i tried to richen the mixture with the SU's but the same thing is happening, i've tried alot of things... but to no prevail... this happened to anyone else stock L26, with 240z Su's everything stock.. engine close to seeing its last legs, but it was working all fine this week... so i wouldn't think its the engine... ahh i really do not know what is goin on.. Quote Link to comment Share on other sites More sharing options...
Guest lambsr Posted July 28, 2001 Share Posted July 28, 2001 'Sounds' like a classic lean running condition - the popping is probably spit-back through the carbs. Manifold air leaks are the most likely cause but another possibility is low fuel pressure or low float-bowl fuel height. Of course this assumes everything else is spot-on (eg ign timing, valve clearances, etc). Try to avoid making 'random' adjustments to the carbs in response to something like this as it's unlikely that they'd suddenly go out of adjustment so drastically of their own accord. Quote Link to comment Share on other sites More sharing options...
Guest Zpeed Posted July 28, 2001 Share Posted July 28, 2001 so what should i do, tighten up everything make sure there is no air leaks??? Quote Link to comment Share on other sites More sharing options...
Guest lambsr Posted July 28, 2001 Share Posted July 28, 2001 In the first instance certainly check all bolts for tightness. If the manifold gasket is old that's another possibility. You should also check the plugs for signs of wide mixture variations between cylinders (eg one plug markedly different from the rest may indicate a bad plug lead). Quote Link to comment Share on other sites More sharing options...
Guest Zpeed Posted July 31, 2001 Share Posted July 31, 2001 i got a 260z with a 240z carbs, still can't find the problem out, the carbs both lift the same.... i'll try some of the things you said and see how it works i've checked the alternator, the spark plugs showed that it was running rich, because they were quite dark, and i only changed them about 3 months ago, and i hardly drive the car, could be the coil, but i think its a fuel problem... [ July 30, 2001: Message edited by: Zpeed ] Quote Link to comment Share on other sites More sharing options...
DAW Posted July 31, 2001 Share Posted July 31, 2001 At the risk of sounding oversimplistic, I'll offer some possibilities. The sudden onset narrows the troubleshooting scope some. A arb linkage problem could have put the two SUs way out of sync, including the fast idle/jet retractor linkage stuck on one carb; a suction piston could be stuck down in one carb due to varnish build-up; you may have a bad tank of gasoline; you may have a carb float stuck partially shut or a gummy restriction in the fuel supply line to one carb, you may have an ignition system problem (which shows up under load and throttle blips, idles but won't accelerate). To crudely narrow this list down some, you could remove a plug wire, put a phillips srewdriver tip in its end and hold it 1/4" from a ground with the car running, spark should be blue and stout, if it's feeble and orange or won't jump the gap, you may need ignition system work. Pull the air cleaner and lift an SU piston with your index finger: same effort to lift each? Do they drop about the same if you let them go from top of travel? Check the linkage for missing screws, etc, and work the choke: do you have full travel at the carbs for each carb? Push off choke: are both jets returning to the off position? You may have to run the car and individually to each carb, apply some choke (...wait a minute, did you say 260Z? If it's stock, then you'd have HIF squaretop SU/Hitachis and have a choke plate, not a mobile mainjet...oops) DAW Quote Link to comment Share on other sites More sharing options...
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