Can anyone help here just got my z running been 20 yrs since last time motor starts ands idles great but cant get the rpms up above 3000.rpms hit 3000 then drop to 2500 and back up to 3000 its not spark because i hooked up a tester and the sparks never stop even as the motor goes down to 2500 so i figure its fuel but where to i start?

ok i figured it out and figured all should know the problem was in the throttle positioning sensor had water in the connection

Another problem you may run into is low fuel pressure because of crud in the fuel tank. This caused the exact same problem with mine.

My Z is having the same symptoms. My engine is fairly good it only has around 84000 miles on it but today something weird started happening. First gear was good and so was second at 3rd gear my car wouldn't go over 2500 rpm i would literally have my foot down on the gas and it moves like i just downshifted or something and if i keep it on the gas for to long the muffler sputters like as if a cartoon car just broke down. So i drove home at low speed from the base i work to look in my engine. I found pieces of a belt but I'm not sure where it came from. Also my gas just start dropping like a rock in water idk if that's connected to do my problem. Can somebody point me in the right direction cause nobody in panama city knows how to work on my car and i would rather get what i need to fix my car and do it myself. My engine right now is the original L28E. So would it be both of these problems and something else or something different altogether?

You should get hold of the FSM before you do too much hunting. It could be a range of sensors making it run rough. Is the exhaust black and sooty and how are the spark plugs?

If you are handy with a multi-meter You can try these tests http://www.hiperformancestore.com/Ljetronic.htm and check the distributor pick-up using the steps in the FSM manual here http://www.xenons30.com/

Good luck. Chas

Thanks there is no black smoke that was the first thing i checked.

fuel filter blocked? do the test for fuel that are recommended in the FSM.

If the car still runs then it must have been the ac belt that tore loose. There's only 2 on my '77, the main water pump, fan and alternator belt then the ac compressor belt. If that belt came loose it could have knocked some vacuum lines off around the distributor advance or BCDD. That could cause a bad running motor.

If the car still runs then it must have been the ac belt that tore loose. There's only 2 on my '77, the main water pump, fan and alternator belt then the ac compressor belt. If that belt came loose it could have knocked some vacuum lines off around the distributor advance or BCDD. That could cause a bad running motor.

Or the water temp sensor, thermotime switch, etc.