73 240z not running right!

[ramrod1283]

Well first of all I got a 2.5 inch msa header and complete exhaust system just installed. Before I blew it apart it ran good. Now I have trouble starting it, idle is not consistant, it stumbles when you go to rev it, and also when I go to take the #2 spark plug wire there is little change in the idle. When i go to take off the #3 spark plug wire there is no change. Also before I took it apart my electric fan and fuel pump worked fine and now when you turn on the key it does'nt come on at full power. I'm a newbie so any helpwould be greatly appreciated.

Thanks,

Chris P.

[Zed Head]

Well first of all I got a 2.5 inch msa header and complete exhaust system just installed. Before I blew it apart it ran good. Now I have trouble starting it, idle is not consistant, it stumbles when you go to rev it, and also when I go to take the #2 spark plug wire there is little change in the idle. When i go to take off the #3 spark plug wire there is no change. Also before I took it apart my electric fan and fuel pump worked fine and now when you turn on the key it does'nt come on at full power. I'm a newbie so any helpwould be greatly appreciated.

Thanks,

Chris P.

More clarity needed. "Before I blew it apart" - what does that mean? "before I took it apart" - is it apart now? You said that you "got a header etc. installed". That implies that someone else installed them. Do you mean that you installed it, blew it apart/took it apart, and when you put it back together these problems appeared? "before I took it apart my electric fan and fuel pump worked fine and now when you turn on the key it does'nt come on at full power". The fan or the pump or both? "It" is singular.

If you took it apart and put it back together, describe what you took off to get the header on and any problems you had putting it back together. There might be some clues there.

Just trying to help you describe the issue...

[Kurbycar32]

I dont see how the electric fan and fuel pump are related, except maybe you bumped something during the header installation. Did you adjust your carbs to compensate for the new header? Installing a header increases the breathing ability of the motor. Your motor is now sucking in more air and it needs to be compensated with by adding more fuel, if you haven't accounted for this your motor is likely running way too lean and running poorly. Lean conditions make for hard starting, excessive engine heat, backfiring on deceleration and a few other things. You did the right thing by checking the spark plugs but if you dont have a bunch of mileage after you changed the pipe the plugs may not read white or light grey yet, a symptom of lean conditions.