I have a 1996 Buick Roadmaster Wagon with the 5.7l LT1. The car has a little over 130k miles and seems to run well. However, I took a look at the fuel trims and I think they tell a different story. Recently the in tank fuel line that goes from the pump to sending unit ruptured. After fixing it I decided to take a look at the fuel trims.
Bank 2 seems to have a lean condition. I'm thinking bank 1 may be ok for the time being?
Here's what they look like shortly after starting.
In case the links don't work. STFT B1= -0.78 LTFT B1=5.46 STFT B2=-0.78 LTFT B2= 20.28
i1254.photobucket.com/albums/hh605/haze5.../20190913_171313.jpg
And while revving up to about 2,200 rpm. STFT B1= 1.56 LTFT B1=8.58 STFT B2= 0.78 LTFT B2= 13.26
i1254.photobucket.com/albums/hh605/haze5.../20190913_171347.jpg
After running for a while bank 2 started coming down a little. So did bank 1 but bank 2 seemed more significant.
STFT B1= -0.78 LTFT B1=3.12 STFT B2=-0.78 LTFT B2= 14.82
i1254.photobucket.com/albums/hh605/haze5.../20190913_172355.jpg
Here's what the upstream o2 sensors were doing.
i1254.photobucket.com/albums/hh605/haze5.../20190913_171532.jpg
After fixing the ruptured fuel line I tested fuel pressure at the test port. I have 44 psi on prime. After prime it drops to about 40 psi and holds steady. I let it sit for a few minutes to make sure it would hold. I'm getting 34 psi while running. Disconnect the fuel pressure regulator vacuum line and I'm back to 44 psi. The manual states that pressure should drop by 3-10 psi when engine is running. So I'm at the upper threshold of 10 psi.
I'm not sure where to go next and could use a little guidance. Should I be looking for un-metered air getting into the system? Vacuum leak? Intake gasket?
Thanks.
