Where did my gauge fluid go

[V8guy]

One of last winters projects was the hydrostatic fuel gauge on our 35. I removed the gauge cleaned with acid water then isopropyl alcohol. Removed the sending unit blew cleaned it and blew out al the tubes with compressed air. I also blew out the gauge line while it was disconnected from the tank unit. Filled the gauge with new gauge fluid let it stand over night re checked still on the empty line. reinstalled every thing add 10 gal of fuel gauge was at about 3/4 looks good. worked ok for a few days then the fluid disappeared. Removed the gauge no fluid in it took it apart again looks like the flub burped over the glass tube into the gauge. IDEAS

[FrankWest]

I think it evaporates, anyway this gas gauge is hokey at best.
10 years ago I purchased a new fuel line from Ray Nachize Spelling incorrect. But the fuel line was perfect, installed it and installed the fuel gauge line which was attached to the mail fuel line. Worked perfectly for several months then the fluid vanished. Either the fluid evaporates or back pressure causes it to drop back into the fuel tank?
Many people forget it and insert a red pip cleaner in the viewing tube.
I find it amazing that such a hokey device was actually part of the ford automobile.
I wonder what type of fuel gauge Packard and other high-end autos used during the same time frame.

[T Scott]

The vent in the sender may have become plugged. If that's the case, any pressure in the fuel tank will push the red fluid out of the gauge. This is a simple manometer, and still used today in many applications but must be kept clean. Any crud in your tank could foul the vent. A vented gas cap could help but then you run the risk of fuel seepage when the tank is full. Also, as a side note, blowing the line out with compressed air could introduce water in the line which would have a negative effect.

[deuce_roadster]

My 32 and 33 with stock fuel gauges that I restored (as well as senders) over 10 years ago still work perfectly. After the car sits for an extended period, you have to drive it around and let the gas slosh around for the indicator level to come back up. You can accomplish the same thing by rocking the car from side to side. I believe the airline pressure eventually bleeds back to the tank.

[JimG]

I have experienced the same thing. I thoroughly rebuilt the gauge last year following instructions from deuce lover and it seemed to be functioning OK with the tank fairly low. When I filled it up at the gas station, the minute I pulled away from the pump the pressure in the tank blew the red fluid out of the gauge. I saw the air bubble push the fluid out. I have screwed around with it some more this year, with the same results. When the tank is less an 1/3 full it works OK. If I fill it more than this it blows the gauge. I have not had time to investigate further. I have never tried to look at the unit inside the tank. I suspect that is where the issue is. I had it working better a few years ago before I rebuilt everything completely. At that time, it functioned but only went up to about half when the tank was full.

[FrankWest]

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thar she blows. That guage is a pain in the ass, buy a meter stick to measure the gas level.

[glennpm]

As mentioned don't blow into the airline with your damp breath.

[Terry,OH]

The only way the fluid could come out of the gauge through the glass sight tube is excessive pressure in the gas tank. Check the fuel tank hydrostatic sending unit. It has a vent tubes that have a small holes that can become plugged also small holes at the bottom of the sender. I clean the brass with liquid toilet bowl cleaner (the blue stuff) clean well with lots of water and blow all the passages out with low pressure compressed air. Make sure none of the solder joints are cracked If so they can be resoldered.
Suggest before reinstalling your gauge or the sender blow very low pressure air from the gauge end through the tubing just to clear the tube of any fuel that may be in there.