That spring under the fuel tank isn't the only one that you're pushing against on those. There's a compression spring up under the dash. That thing's wound like an 8 day clock. You might be able to make it easier to push if you took it out and cut some coils off of it,but I'll warn you,that thing is TIGHT and it's a pistol to get back in there. Mine flew out when I took the pedal off to put a new pivot bushing in it last summer. It took my son and I quite a while to get it back in. If there were some coils cut off it would be easier to get back up in there for sure.
You have to take that square edged panel off that you see right next to the pedal when you open the door. There's a rod that runs straight up and goes through a hole higher up. That spring is on that rod.
I'd try unhooking the linkage under the tank first and see how hard the pedal alone pushes.