drain fuel tank without droping

The best is to drop the fuel tank, you will also need to drain or vacuum out your fuel lines and system, best bet is to take it to a qualified repair technician and do this.

ONE GREAT WAY TO DRAIN A FUEL TANK WITHOUT A SYPHON HOSE IS WITH COMPRESSED AIR...If you have an air compressor, you can purge the fuel tank with compressed air which in turn would pump the remaining fuel out through the fuel return line. This technique worked great on my 94 Chevy S10. Because the fuel tank had a one way valve in the filler tube which blocked the siphon hose from getting to the fuel at the bottom of the tank, I had to find an alternative method. Siphoning is a joke anyway, either your sucking on a tube full of gasoline or jacking the hose off all day, and it's dangerous. To drain the fuel, first I blocked off the two lines going into the tank from above, out of the four, that I wasn't going to be using. For my truck these lines were the vent hose going into the charcoal canister, and the fuel line going into the fuel filter. This can be done by screwing in a bolt into the hose opening or keeping the fuel line connected to the fuel filter (since this line is purged with fuel all the way to the injectors it won't be an escape route for the pressurized fuel). Next I used the fuel return line as the drain line and the filler hose that returns to the filler tube as the line that would be pressurized with compressed air. With a drain hose connected to the disconnected fuel line draining into a gas can and the filler tube hose connected to the end of a compressed air nozzle with plumbers tape and a hose clamp, I was able to pump the fuel out of the tank with air. I also blocked off the nipple on the filler tube that I left exposed and kept the gas cap on to keep the fuel tank sealed. This method worked great on my S10 because the return fuel line from the fuel injectors although entering the tank from the top, went all the way to the bottom of the tank where it could suck the fuel out like a straw. I also connected the compressed air to the filler tube rather than the vent hose because it was bigger and it didn’t have a rollover valve that could be damaged. This might not work on all cars and you might even be able to pump the fuel out using the fuel pump by only disconnecting that line and running the pump. That might be dangerous however because the first step to removing a fuel tank is to disconnect the battery. Also be careful NOT to fill the pressurize the tank with too much air for this might damage the tank. Hope this was helpful! -DragonSurfer29