Gas tank screen

mightymanx · Post by **mightymanx** » Sat Mar 22, 2008 5:17 pm

I was wondering if the screen inside the tank is really needed. I have been having problems with what seems to be running out of gas but I still have about 2 gallons left in the tank. I looked in the tank and the screen that is in the tank seems to be bent over and almost flush with the fitting in the tank and my thought is that the open area of the screen is reduced and there is not enough to allow adequate fuel flow when the tank gets low. I have changed the fuel filter and pump and the only thing that I can see is the screen. When the problem occurs, the engine is only running on 2 cylinders which are the cylinders that are fed from the first carb. I have also checked the float level in both carbs and they are perfect.

manxdavid · Post by **manxdavid** » Sat Mar 22, 2008 7:10 pm

I've run without one and had trouble with dirt from the tank building up and blocking the bend in the outlet tube. I'd just wash the tank out and fit a new screen. You should be able to get a little kit with the screen, the tube, the nut and the fiber washer.

Ed-Chenal · Post by **Ed-Chenal** » Sun Mar 23, 2008 4:56 am

The problem may not be your screen. In most buggies, Manx and clones, the gas tank is not mounted level in the buggy. They are mounted on a forward angle that does not allow all of the gasoline to drain from the tank. A portion of the tank is lower than the drain. Poor design.

newmanx59 · Post by **newmanx59** » Sun Mar 23, 2008 12:44 pm

If I am correct, the stock VW tank has a 10 gal. capacity. I did a test with my buggy last summer and I was able to use 9.2 gallons of fuel from the tank in my Manx. I'm not running a "sock" in my tank and haven't had a problem yet. It will probably come back and bite me.

MojaveMel · Post by **MojaveMel** » Sun Mar 23, 2008 6:48 pm

Usually the screen or some sort of in-line filter is a good idea. Idle jets especially tend to be sensitive to dirt. Sounds like the pickup tube in the tank could be starting to suck air. Like Ed said, the tanks are often turned around for a buggy and depending on the angle at which the tank is mounted sometimes it is impossible to get the last gallon or two because the pickup tube is now higher than low point/sump of the tank. If those look ok, gravity adds a little pressure, but not much. So a full tank of gas does help provide a little pressure on the outflow. It could be that the screen is partially plugged and when the gas level gets low the little bit of pressure from the upper gas in the tank is gone. Sort of like when a fuel filter in a car starts to plug. But usually it will idle and run normally and partially starve for gas when accelerating or climbing, at least at first. If you suspect that you can try putting a few feet of gas hose on the output tube of the tank and blow air backward into the tank. If there is a temporary obstruction that will sometimes clear the problem for a while, at least that might help you troubleshoot whether it is a screen obstruction. Depending on the tank, if it is an early style tank, there should be a big nut on the outlet at the bottom which comes off and gives access to the screen and pickup. It sounds like that is the tank you have. You have to make sure the tank is empty before you remove the big nut. I've seen the same problem ManxDavid describes with crud settling in the bend of the output tube. Hope that helps a little.

Lee · Post by **Lee** » Mon Mar 24, 2008 6:34 pm

Regarding the angle of the gas tank, it is annoying that we aren't able to use that last gallon or so. I had some success by cutting down the portion of the pickup tube that sticks up into the tank. It sticks up to get it out of the muck, but cutting it down gives access to quite a bit more gas. I run a screen, but I am unable to get it into the tank because there isn't enough room between the tank and the top of the frame head. So I cut it down, fold the edges over the top. I run an inline fuel filter under the tank. I am also only able to get 8 or so gallons into the tank because of the angle and where my fuel filler is. There's a large pocket of air that keeps more gas from getting in. Still, with the extra 5 gallons I carry on long trips, I am able to go about 230-250 miles before I run out of gas.

mightymanx · Post by **mightymanx** » Mon Mar 24, 2008 11:48 pm

Thanks to all who replied. I took the screen out and straightened it and put it back in. I then put the gas back in that I had drained out and checked the flow which was very slow when draining the tank. This time it came out quite a bit faster. I will also not run it so low from now on. Thanks again