1FSTMAX

iTrader: (29)

A couple days ago I noticed a little problem with my AFR. I was cruising on the street, and then I went to downshift 4-3 and went WOT. At that point I noticed my AFR was 16.7-17.0, which is obviously super lean. Before that day I would see my AFR at 11.6-12.0 at WOT.

Now I’m thinking maybe a problem with the fuel pump? Or perhaps a faulty FPR? The fuel pressure is set to 44PSI with the vac line off the fpr. If I hook up the vac line to the fpr, the FP goes to 34 PSI at idle. If i hit the gas the FP drops down to like 25-30PSI. Before it would go up to like 40+ PSI.

Any Ideas?

This is a 99 5spd
Y pipe, exhaust, Fed spec conversion, and intake.

JSutter

iTrader: (46)

could be an issue with vacuum on the regulator. if it didnt do it with the old reg then the pump should still be fine and must be the new reg.

1FSTMAX

iTrader: (29)

i did some more diagnosing with the help of jsutter... I was looking at the Fuel Pressure gauge, and with the ignition on there is 0 Fuel pressure. I have to crank the car for a few seconds for the pressure to build up. Also i used to be able to hear the fuel pump when it primed, now its hardly noticeable.

Would these symptoms be indicative of a bad fuel pump?