My '73 240z has a 2.8L engine, a Clifford intake manifold, and an Eldelbrock 1406 4bbl carb. Up until last weekend, it ran like a dream. Then I had a very rough time getting it started (although it would start and run on ether). By enriching the idle needles, it would start and idle well but it doesn't want to run above about 2,000 RPM. It doesn't much like throttle blipping either. I changed the gas line filter (this had been a problem before) and this changed nothing. I checked the fuel pressure (Eldelbrock electric pump) and I was getting 6psi. Since the car is only run about once a month and its a long time between tankfulls, I'm fearful of bad gas or junk clogging the carb, but thought I'd check in for other ideas before draining the tank and rebuilding the carb.

Thanks in advance.

I recommend hybrids I think that there are several guys there running quads.

Thanks Beandip. I'll probably try them, but I was looking for things other than the carb that might be causing the problem. Sometimes I spend huge amounts of time fixing things that aren't broken because I don't check out other issues.

By the way, the previous owner put the system together and I would have preferred the twin SUs, but the 4bbl has been running for four years or so and has given me great service.

I would focus on the return fuel line.

zdisease

I'm not sure what did it, but the beast lives again. I checked all the ignition wire connections and removed the old condenser to inspect it and then put it back. I removed the fuel inlet fitting from the carb (thinking it might have a filter - it didn't) and sprayed carb cleaner directly into the inlet opening. Finally I adjusted the electric choke to specs. I hit the ignition and it fired up like a new car. I leaned out the idle mixture screws and reset the idle speed and then took it out. After a 20 mile test drive I can honestly say that it has never run better. I previously had a transitional stumble at about 2000RPM and that is gone -- just nice smooth power over the entire range.

I have somewhat of a simialar problem also, mine I think is in the fuel tank, just runs about a mile then dies, and then have to leave set or it wont start, after a while it does but the longer you leave it set the better it runs and longer it runs? what could cause that, would it be the fuel return line as you said biddljj

I recently have the same problem on my 77 280z (stock) today. car does not go past 2000rpm. it idles fine but after reving it past 2000, the engine hesitates and jerks when I drive it. I can't figure out what was the problem. Here is a video that I took. Thanks

http://www.youtube.com/watch?v=0O301Dl6WwA

draztik, your car is possessed!!

With fuel injection you really need to check everything. Make sure you do not have any vacuum lines lose. Also ensure your Fuel Injectors are clean.

i checked the vacuum lines, they are all intact. I did not check the fuel injectors yet. I went to the gas station to fill some gas and hopefully will clear out the problem. I bought a fuel filter and I will install it tomorrow. and il probably go buy seafoam to clean the injectors. I will post again if this solves the problem.

Thanks