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Fuel Tank Venting

Yahoo Message Number: 55836
Right after I took factory delivery, and the second time I filled it, I had only 25 gallons to put in before a long run, when I opened the fuel cap , I got sprayed with diesel fuel. The next time I did it and the tank was near empty, it did not do it. When I went back to the factory for a check on this and a few other items , they said that the " roll over " valve or vent was plugged , with tar from the factory corrosion sealant they put on the bottom plugged that vent. The Rollover Vent has a check valve in it to prevent fuel spillage, in case of a rollover. The other reason for it venting, is when there is a large fuel return to the tank, such as when you are operating on high Jake and high RPM , as the engine is flowing a lot of fuel that has to go back to the tank when not being consumed by the engine. When the fuel is returning it causes a pressure build up in the tank and you need to vent the air. On units with the ISX 650 HP these rollover vents are not large enough and the engine " check engine " light comes on. The fault reading comes as " high fuel tank pressure " I believe. It is not a big problem , but CC was to add another Rollover vent but , it obviously never got done because of the bankruptcy.
I am not sure I will add one as , again , it is not a big deal as long as you know about it. The check engine light goes off on a restart

Ron Baran 09 Magna 7025 ISX 650
 

Re: Fuel Tank Venting

Reply #1 –
Yahoo Message Number: 55875
Very interesting information, Ron. My metal tank vent tube was stopped up and I would get a rush of air when I removed the feul cap. Mine was stopped up with dirt - maybe from an insect. I could only go so far with a coat hanger wire to clear it. I guess that is because I now know from your post that there is a check valve in there. So, I removed the metal pipe and replaced it with some plastic hose. Now my fuel tank is no longer pressurized. BTW, Cummins says the tank is not supposed to be pressurized. I guess I will be spillng some fuel if I roll.

George Harper
04 Allure
31093