So first things first. I have a 2005 350z 6MT Base edition. So far i have done JWT Flywheel and Exedy Stage 1 Clutch, Berk Test Pipes and Invidia N1 replica also have a new air filter setup but still same hosing.
Most recently I've been having constant running of my radiator fans, once up to operating temp the fans kick on and wont stop until the car is turned off. Im replacing the coolant temp sensor tomorrow in hopes of fixing this issue. I am also receiving code P1273 which doesn't seem to have a fix anywhere. Could this problem be associated with my fans not turning off now? When installing the test pipes we got the code so changed out all new O2 Sensors, still got the code i bought extenders for the 02 sensors and still no fix. We searched the car top to bottom and unable to find a vacuum or exhaust leak. The spark plugs were changed about 10-15k ago but were new at the time of getting this code. I've have this code for about 2+ years and haven't had any issues with drive-ability just a little bit of lower fuel mileage. Next i just got a code today saying to fix my fuel pump immediately if affecting affecting drive-ability which it isnt. Overall im really lost on where to begin on the code P1273 and if my fuel pump is actually bad. Any help would be greatly appreciated!

 

You don't say how many miles you have but I'll try to help with your 3 problems.
1) radiator fans- go ahead and change the temp sender, hope that helps. Also any time the a/c is on they will run so make sure a/c is off. Since they run only after engine warms up it's possible you have a bad thermostat or even a slow/clogged radiator. An independent mechanic can diagnose in under 20 minutes.
2) P1273- When you installed test pipes you changed the air flow which is confusing your ecu. The easy and correct way to ck for vacuum leak is to connect a guage to the manifold and watch for fluctuations. If you have an exhaust leak you'll see white powder. Have you tried clearing the code with a OBD2?

https://www.google.com/search?source...ile-gws-wiz-hp

3) Not at all clear about your fuel pump comment based on your description. I do know it's not one of the more common complaints here.
gl!

edit- it is possible you may have a leak around the test pipe connections, I'd def inspect those before continuing with that code, look for white/gray powder residue at connections.