Pressurized Fuel Tank...........OK?

[Frankdozer]

My 1984 John Deere 455D track loader runs great and starts up immediately. It starts up almost as quick as my 2010 Dodge Ram 1500. I don't know if this is a problem or not or it could be normal But: The fuel tank cap is the factory cap. It is not vented nor was it ever vented. After normal use of about 4-5 hours, until I know what the fuel consumption is, I top off the tank. When I remove the fuel cap the tank is pressurized so I turn the fuel cap slowly to let the air escape before topping it off. Is this normal operation? By the way, it's a diesel. Thanks, Frank

[77 Ford]

There is more than likely a vent pipe that goes thru the tank and drops out the bottom. Mine was plugged and caused the same problem. I had to put a coat hanger on a cordless drill to get thru the crud and open it up.

From the top it just looks like a hole that comes in right at the top of the filler neck.

[Frankdozer]

77 Ford you were right on the money!!!!!!!!!!!! I saw the vent tube just under the fuel cap and traced it to the bottom of the tank. On the bottom of the tank it appeared as a 3/4" welded on bosement with a 1/8" hole in it. I stuck a 1/16" drill bit up into the bosement and about a teaspoon of diesel fluid and a little mud came out. I then got a coat hanger and pushed and turned it down thru the vent pipe where it then came out the bottom bosement. Now it's all clear. I think a mud packing bug or bee was the culprit. Again, Thanks 77 Ford !!!!!!!!!!! Frank