Hi, guys. My boyfriend bought a school bus a couple of years ago and, with the help of a diesel shop at a local tech school, converted it to run off of waste vegetable oil from restaurants. We had planned on using it this summer to go to a bunch of music festivals (for which we have been hired for volunteer work and have already sent in non-refundable deposits). In order for the system to work, we suck the oil into a bulk tank, then it is pulled from the bottom of that tank by way of a fuel transfer pump that should then (conceivably) send it through three progressively downsized (in terms of microns) filters and on to the day tank for heating. This system worked relatively well for his trip across country two summers ago, although he says that it would often have problems that would work themselves out if it was left alone for a few days. Now, however, we can’t get it to pump more than a couple of gallons through the filters. We’ve checked all the lines, tried three pumps, and done just about everything else that we could think of. We have tried cycling it from the bottom of the bulk tank, through the pump and then back into the top, and that works beautifully. It is only when it gets to the filters that the problem arises. If we change the filter cartridges, it will work very well, but it will taper off after those first couple of gallons. Change the cartridges again, works well for a couple of gallons, then nothing. This has happened with two different systems of filter housings! Obviously, we cannot afford to keep changing the filters this way (we might as well run on diesel.) Please, do you have any ideas?