Hello , this is my first , couldn`t find any info ... I have a 1994 Jeep Cherokee Sport 2wd, with the 4.0 inline 6 . I was checking trouble codes and got a 39 which doesn`t appear in the service manual . There were several other codes , all valid ( 51,21 , 27, 55 ) . Does this mean the ECU or the ignition module r bad ? if not , what does it mean ? Thanks in advance !

 

Hows it run?

 

Hello , thanks for the reply . Well, the fuel pump , when I turn the key , runs for 8 seconds instead of three , it takes several tries to start up ( it turns over well () , and it runs very rough for about 25 seconds . After that , it runs fine except that it bogs down somewhat on acceleration .
I know I`ll have to replace the O2 sensor , but I suspect , from reading the manual , that I`ll have to replace one or more of the following : pressure regulator , fuel filter or fuel pump . I`ll know more when I`ve donrwe a fuel pressure test .
Meanwhile , any insights into what I need to do ? I`m not familiar with Jeeps lol ! Thanks in advance !