Attention: TDR Forum Junkies Maybe one of you can help me sort out this issue. What should the reading be on the FASS 95 pump? How steady should that reading be?
Background: I have the FASS 95 (16 psi transfer pump) installed on my truck. The pressure reading started getting flaky awhile back (needle bouncing all over the place at steady rate of speed / throttle). Took it in to the shop and an external fuel pressure gauge indicated that the pump was only putting out about 3-5 psi at idle. The Westach gauge was reading 8-10 psi at the time. The FASS was still under warranty, so in it went and FASS sent one back (not sure whether they replaced it entirely or just R&R'd the old one). While I was at it, I changed out the old Westach gauge for an ISSPRO gauge, something that I'd been meaning to do for some time.
All OK -- the new gauge was reading about 16-18psi at idle, and only pulling down a few psi uppon acceleration. The needle moved smoothly. All was good with the world.
For about a week... ... . #@$%!
Now it still reads 16-18psi at idle, but the needle seems to jerk around a bit. Goes down to 12psi or so on heavy acceleration. Most significantly, while driving (no load) at steady throttle, the needle jumps all over the place; from 12-15-16-18psi and back again.
For the record, the new fuel gauge is the ISSPRO electric fuel pressure gauge, remoted by a hose from the Schrader valve on the VP-44 and with the sensor mounted on the sheet metal just above the driver's side wheelwell. So I don't THINK it's inducing excess vibration to the sending unit, but...
Any ideas on what might be causing this? Do I have two bad gauges in a row, from two different manufacturers? Or is the FASS bad? Is there something that I may have overlooked here?
Just not sure how "steady" the pressure from the FASS is supposed to be, so that I can figure out what "normal" should look like and troubleshoot the problem from there.
Ideas?
Background: I have the FASS 95 (16 psi transfer pump) installed on my truck. The pressure reading started getting flaky awhile back (needle bouncing all over the place at steady rate of speed / throttle). Took it in to the shop and an external fuel pressure gauge indicated that the pump was only putting out about 3-5 psi at idle. The Westach gauge was reading 8-10 psi at the time. The FASS was still under warranty, so in it went and FASS sent one back (not sure whether they replaced it entirely or just R&R'd the old one). While I was at it, I changed out the old Westach gauge for an ISSPRO gauge, something that I'd been meaning to do for some time.
All OK -- the new gauge was reading about 16-18psi at idle, and only pulling down a few psi uppon acceleration. The needle moved smoothly. All was good with the world.
For about a week... ... . #@$%!Now it still reads 16-18psi at idle, but the needle seems to jerk around a bit. Goes down to 12psi or so on heavy acceleration. Most significantly, while driving (no load) at steady throttle, the needle jumps all over the place; from 12-15-16-18psi and back again.
For the record, the new fuel gauge is the ISSPRO electric fuel pressure gauge, remoted by a hose from the Schrader valve on the VP-44 and with the sensor mounted on the sheet metal just above the driver's side wheelwell. So I don't THINK it's inducing excess vibration to the sending unit, but...
Any ideas on what might be causing this? Do I have two bad gauges in a row, from two different manufacturers? Or is the FASS bad? Is there something that I may have overlooked here?
Just not sure how "steady" the pressure from the FASS is supposed to be, so that I can figure out what "normal" should look like and troubleshoot the problem from there.
Ideas?
