SolarYellow05

I have a 94 12 valve auto. From idle to 2000 it maintains a steady 20 psi fuel pressure, but as soon as it hits 2000 rpms, the pressure starts dropping. Anybody have any input on this? I haven't started troubleshooting this yet. Just wondering if anyone has had the same problem so I'd know the best place to start.

Dartmouth 12V

There are three normal causes of low fuel pressure on a 12V. The first thing to check is to make sure that your fuel filter(both the prefilter and cannister filter) isn't clogged. Another is the lift pump which only rarely dies. The other is that the overflow valve isn't working right. To check the overflow valve, try pinching off the fuel return line some and seeing whether the pressure stays up. If so, the valve is bad. If it isn't the overflow valve and it isn't the filter, it is probably the lift pump. In rare cases, there can be a bad enough air leak that it causes these symptoms but you usually will have serious starting issues first.

SolarYellow05

Ok. I've installed both filters and it didn't help. There is no trouble starting the truck, so I'm not thinking there's an air leak. I'm thinking either lift pump or overflow valve.