JMUBullnose Posted October 25, 2018 Share Posted October 25, 2018 Alright - I decided to wait and see if I was imagining things but I am fairly positive that I've somehow got a siphon between the rear and front fuel tanks on my truck. I filled up the rear tank all the way, front tank was empty - day or two later I get in and the rear tank is down 1/4 and the front is up to 3/4. What on earth?? What do I need replace or fix here - thoughts? Suggestions? Therapy? Cheers. Link to comment Share on other sites More sharing options...
Gary Lewis Posted October 25, 2018 Share Posted October 25, 2018 Interesting. The way I read the Fuel Systems/Fuel System Part #'s/Fuel Tank Selector Valves page, your truck should have a 3-port valve and a mechanical fuel pump. If that is the case then the only way the transfer can be happening is if the valve is bad and there is either siphoning or at least a transfer due to gravity going on. So the first thing to do is to ascertain what kind of fuel system you have. Does it have a mechanical pump on the engine and a 3-port valve, meaning there are only 3 lines to the valve on the frame under the driver's seat? I ask because the normal way this happens is with the notorious 6-port valve, which is known to return fuel to the other tank from which fuel is being drawn. (As Ray Cecil about that.) But if you have a 3-port valve then there's no return. Link to comment Share on other sites More sharing options...
BuggTruck Posted October 30, 2018 Share Posted October 30, 2018 Going to keep an eye on this thread. My tanks also siphons, largely influenced by gravity. Hasnt happened since i stopped using the rear tank though. My rear tank has issues i dont feel like fixing right now. I assumed it was because the filler hose was worn and causes an air leak into the tank. Link to comment Share on other sites More sharing options...
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