x91j

hey guy been getting reallly bad mpgs in my 95 zj 4.0 latley and ive already in the last month replaced plugs, wires, cap and rotor, ccv elbow and hoses, air filter and fuel filter and shes running rich my plugs are already black. what could be the problem?

x91j

so i think i just found that my car has no pressure regulator on it. how is it running???

trucker

See if the injector cleaner will work. Any codes?. The O2 sensor will make the engine run rich. The MAP sensor will do it too.

ol"blue

On the '97 ZJ the fuel pressure regulator is an integral part of the fuel pump module and can't be replaced separately.
Dan

x91j

thanks guys. there was no light but i checked the codes and it was code 21 or something like that and it said that my 02 sensor was staying at 4.5 to 5 volts

tiwvr1

that o2 sensor reading that voltage will cause it to run super rich

x91j

ok so thats my problem. ill be putting a new one in in the morning

trucker

Disconnect the negative before replacing and reconnect after repair.. That will reset the computer code.

x91j

ya was going to do that. i just find it wierd theres a code but no light