Hey guys, I hate to bring this up again. I remember talking about what to do if you have pressure in your fuel system when u take the cap off to fill up and I cant find it. Does anyone have the link or info on what to do because today when filling up i noticed it went ppssssssshhhhhhhhhh again and I'm wondering if that is whats causing my 12.5 mpg mileage? Thanks

 

If you are thinking of the vent cap they forgot to take off, look on top of your tank. It is kind of hard to see, you might just feel around. You will know when you feel it. Hope this helps.

 

Here ya go Dude....

http://www.dodgeram.org/tech/dsl/ISB/low_power.htm

Hope this helps.

 

If I over fill my tank and put fuel up into the filler tube, it will leak out of the top of my tank. I thot that the fuel system was supposed to be a sealed up system do to the EPA. Whats the reason to have a sealed up or air tight cap, if the tank has got a air vent on the top of it. If air can get in the top of the tank, I would think dust and dirt could get in also. Unless Dodge installed a one way check valve. Told my dealer about leak on top of my tank and he said it should not do that. But maybe they don't know about the vent, if their is really suppose to be one. On older cars if they did not have a vent some place, the fuel pump would suck the tank flat. I,ve had to have mine blowen back out a few times untill I drilled a small hole in the filler cap. I do have a aux. tank in my truck box, piped into my filler pipe. When aux. tank is empty I leave all the valves open and it seems like I get better milage, this is due to more air going into the tank, I think. Waam Holland, Mich.

 

The little vent down at the sending unit was designed to allow some air in to keep the tank from collapsing. On some 98.5s and 99s, they factory left the red vent cap on and the ended up replacing some fuel tanks.

Any aftermarket mods could easily change this data...

 

I also had the cap still on. Inside of this vent is a rollover valve. I read about some folks having problems with plugged valves, so I put a lenght of fuel line on the vent and finished it with a lamwnmower fuel filter pointing downwards right beside the filler neck. Air can get in and out, water will drip out of the filter. Works nice for me for the last 75000 miles.

AlpineRAM

 

Mine just recently started developing a vacuum in the tank as it empties. ???????????

 

[quote author=Dieseldude4x4 link=board=5;threadid=22912;start=0#msg215014 date=1069976350]
Mine just recently started developing a vacuum in the tank as it empties. ???????????
[/quote]

Vent could have got clogged with something.
Dirt, mud, small animals.


phox

 

[quote author=phox_mulder link=board=5;threadid=22912;start=0#msg215023 date=1069979440]
[quote author=Dieseldude4x4 link=board=5;threadid=22912;start=0#msg215014 date=1069976350]
Mine just recently started developing a vacuum in the tank as it empties. ???????????
[/quote]

Vent could have got clogged with something.
small animals.


phox
[/quote]

 

The vent better discribed as the rollover valve has two functions. It has a plastic diaphram that seals if you roll over and liquid hits it. It also has a spring loaded diaphram of solid plastic that when working properly holds some vacuum in the tank. I wrestled with mine for a while and then took it out, drive the valves up through the top of the vent, put the roll over valve back in, glued the cover back on. Never had a problem since then. And no, the cap does not have a valve in it, it seals almost good.