Hi,

my 4.6L 2004 Heritage recently threw codes P0174 and P2198 which caused me to first clean the MAF then check the fuel pressure. The pressure was 27-28 psi at cold idle and did not change when I removed the vacuum line from the fuel pressure regulator (the line registered 20 inches of vacuum when checked).

1. Does 27-28 psi indicate I must put in a new fuel pump?
2. Since the fuel pressure did not change when I removed the vacuum line, does this necessarily indicate the fuel pressure regulator is bad? (Please say it ain't so -- mine is incorporated as part of the fuel rail rather than being a separate piece.)
3. What other tests should I do next?

p.s. the truck is running great except for the check engine light

Thanks,

JD

 

Change the front O2 on the driver's side.

 

Thanks for your reply GLC.

Since I first posted, P2196 has shown up. Both O2 sensors have less than 4K miles on them. Is it likely they both have gone bad? Perhaps instead they are open trying to respond to the lean condition indicated by P0174?

In any case, would bad O2 sensors cause the fuel pressure regulator problems that I described?

 

Okay - that changes things a bit. You do need to correct the lean condition before condemning the sensors.

I'm afraid it looks to me like the regulator may be bad. However, when was the last time you changed the fuel filter?