The pedals interface via an A-Pac. If I go into the Game Controller control panel in windows I can make the crosshairs go up and down and side to side in the test mode.
When I tab into a game's control mappings and try and set analog pedal it sets just fine as J1 X Axis, or J1 Y Axis depending on which pedal I hit.
But when I start the game I have no pedal input.
Question: In the windows control panel, does the pedal start in the the center, or to one side and top or bottom? And are you using the current mame? These will make a difference on remapping. Assuming you're using a current mame...
Make sure you're remapping "pedal analog", NOT the inc or dec. The latter two are for digital inputs (buttons, keys, etc) pretending to be analog (digital in -> analog out); since you have the real thing, use the analog (analog in -> analog out). Also, remove the the same axes from the inc & dec.
Next, if your pedals start in the center in the Game Cotroller control panel, you'll want to map the correct half. After remapping like normal, press enter again and move the pedal again. You'll see "J1 X Axis" change to "J1 + X Axis" or "J1 - X Axis" depending which half of the axis the pedal covers.
OTOH, if your pedals start on one side, after remapping you may need to set mame's pedal to reverse in the analog controls UI menu.
Also, check that both mame's and windows' dead zone are small (or zero).
On a personal note, I hate digial pedals even if I "pedal to the metal" 95% of the time. That 5% of the time makes a huge difference.