My fuel pressure is normally 45 - 50 psi, but now it's 34-40 psi. It runs 35 at 4000 rpm and and stutters. I replaced the fuel filter, but it didn't help. I get 13.41v at the fuel pump connection at the fuel pump relay. I also have been gettting codes for the MAF 33,34,36. It have a broken connector and I have had the low signal from the MAF intermitently since I bought the car. The too high and burn off codes are recent. I think the problem is a bad fuel pump, but I hope you can tell me it's something else. How can I be sure it's the fuel pump?

 

there are many variables at the issue. I just say that cause it makes me look smart. A weak pressure regulator is a possibility.

 

The pressure regulator is adjustable. I can back it out until it gets to 40 psi and then the psi goes down with further turns out. I think this is because 40 is all the pump can put out.

 

To see if it is the regulator, clamp off the fuel return line and check pressure. If it is still low, it is the pump. I just had to replace my pump. It actually isn't that bad of a job. Just take your time.

 

The pressure shot up so I only have change the regulator. Thanks for the feedback.