my friend gave me his old fc just for kicks...
its a 86
but it has wut i think is a fuel problem but not sure...

what is does it starts up fine but it will not go pass 4000 rpm it boggs
is it a fuel thing or what should i look for???

 

Possibly a secondary injector problem, but more likely a clogged cat.

 

its not the injectors i we replaced those
so it can be the cat???? how does it clogged??
but now that u say that it makes seens bcause it trowwing smoke back tru
where the manifold and the down pipe hooks up to....

 

try to pull all the exhaust (except header) off and see if it revs up.

 

What happens is the first precat fails and comes apart clogging the second.

More likely its a grounding issue, injector wiring grounding out will cause this. Pull off the ECU connector and ohm out each pin. Look for abnormal readings, refer to the FSM for help.

 

It sounds like the very common 3800 RPM hesitation. The most common cause is a bad ECU ground. See this writeup:

http://www.aaroncake.net/rx-7/grounding.htm

 

i pulled of da cat and what it does now it hesitation at 4 but now it keeps goings passed 4000..
before it would not go pass 4000 like if it hade a gorverner...at 4000

i check all ground they all look fine....

 

what condition are the injector wires in? if theyre cracked then they might need to be replaced. you can go to a junkyard and cut off the wires and plugs(leaving plenty of length) and splice them in.

 

Check injector wiring. Pull off the ECU connectors, figure out which are the injector wires from the FSM and ohm um out.