We spent quite a bit of time testing different lighter fluid combinations. We found that the amount of flame you get is related to the amount of surface area that you have coated with lighter fluid. Putting crumpled up paper in a pie plate and then soaking it worked really well.
The picture above is just a pan full of lighter fluid. Those flames just weren't adequate for our needs. We needed more surface area for lighter fluid to work.
See the Pyro Techniques page for more information on ways to get bigger and more visible flames for your pumpkin.
When I am not carving pumpkins, I run a bulletproof vest company. BulletSafe Bulletproof Vests are the value leader in body armor. We are very popular with people like armored car operators and ATM repairmen.