When you're driving your car or truck, it's second nature to keep an eye on the fuel gauge and fill up when necessary. For those who drive their vehicle until it actually runs out of fuel, it's probably best if you don't read any further as none of this applies to you! Sometimes the gauges weren't terribly accurate, but at least you had a feel for how much traveling time you had left. Modern gauges leave even less to chance, many having a digital readout which tells you how many miles you've got left in the tank before it's essential to find a gas station.
So, how about on the old engines with no modern technology to help out? Some are quite easy to judge, having an external or accessible fuel tank which can be agitated and listened to, or have the filler cap removed and the level squinted at, trying to catch a glimmer of light on the surface of the liquid to enable an accurate guess at the quantity inside. But not all engines are so easy .

Can anyone figure out an easy way to check fuel level on a 5HP Economy?

A simple, straight-forward question on the surface, but very often, in the dark winter months, cabin fever strikes, and the most basic query can result in a flurry of mails to the Stationary Engine list with suggestions ranging from the obvious to the obscure. I'll leave it to you to decide when the writers have their tongues firmly in cheek.

Here's a good tip we use out in the bush.
Carry a length of small diameter rubber hose, maybe even garden hose. Poke that down into the tank ( it should be flexible enough to go round the bends) then blow into it. If you hear bubbles, then there's plenty of fuel. This is not definitive as if the fuel level is low you may not get many bubbles. In this case the idea is to suck on the hose. Obviously if you don't get a mouth full of fuel, then the tank's empty and should be refilled.
Oh, it helps to have a willing mate, plied with booze, to do these tests. That way he won't notice the afte- taste.

* A variation on this may be to use small diameter clear plastic tube, put it into the tank to the bottom, THEN COVER THE OPEN END WITH YOUR FINGER and draw the tube out . The fuel level in the tube should be the fuel level in your tank.

First you need a Hercules or Economy engine. The filler tube has TWO 90 degree turns in it.
Simply put, the first step in starting one of these engines is to grab a can of gas and fill the tank. I learned that lesson well during my New Year's Crank-up!

* I'm thinking of a device modeled after a tympanometer, that's used to determine whether there's overpressure, or vacuum, or fluid behind the eardrum. This'll be simpler than the tympanometer, because all we have to do is measure the air volume in a closed space. Put a port in the tank closed off by a small speaker driven by an amp of known,
constant power. It'll be putting out a very low frequency at fairly high volume so there's a lot of excursion of the speaker cone/diaphragm. Next to it in a branch port is a pressure
transducer/microphone that measures the pressure fluctuations in the enclosed space produced by the known air displacement of the speaker cone which is acting like a piston in a cylinder bore. This acoustic impedance is directly related to the air space in the tank, which gets smaller as the tank fills. (Can't fill it to the transducers!)
You can do lots of calculations to predict the results at different volume levels, or better, just calibrate it by running it with different known volumes of gas poured into an empty tank.
Another workable alternative is to affix a simple whistle to a port in the tank, with the whistle bore opening into the tank. When the whistle is blown, the frequency produced will be a function of the air space remaining in the tank, which is a Helmholtz resonator.

* You certainly have laid out some nice technical solutions to the gas tank problem.

A solution that came to mind as I read yours is to use a piece of clear vinyl tube, insert it into the gas tank with a loop outside hanging below the tank and with the end higher than the tank. Suck on the tube until gas appears and is lower than the tank. Then, watch as the gas climbs to the level of that in the tank. IF a depth marker with volume equivalents is affixed to the outside of the engine, the volume of gas in the tank can be easily determined. The calibration of said marker is simple. Put in a known amount of gas into an empty tank, enough to start the syphon level process, then, without removing the syphon, keep adding known quantities of fuel and placing corresponding marks on your depth marker.

* This is getting pretty serious. Why not just weigh the engine periodically? Then add fuel till the weight is back up to where it should be.

* Four methods checking fuel level come to mind:

1) Use a sight gauge. That's what I've got on the Hoyt-Clagwell.

2) Put a petcock close to the top of the tank. When filling the tank, open the petcock. When fuel comes out, the tank is full. That's what I've got on the Fairbanks Morse "T".

3) Take off the fill cap and tip the engine over. Angle of tip is inversely proportional to the amount of fuel in tank.

4) Fill it up every time you look at it. If it doesn't start, fill it up. If it rains, fill it up. After taking out the garbage, fill it up. If you sneeze, fill it up. If your wife hollers at you to quit fooling around with that infernal dadblasted dirty old junk and come in to dinner, fill it up.

* My Hercules S has the same type of filler tube with two 90° bends. I was SURE there was plenty fuel in the tank when I wanted to fire it up yesterday. Here are my comments concerning your suggestions for checking fuel levels.

1) My Hercules wasn't designed with a fuel gauge, and none of the previous owners added one. I won't either.

2.) see #1

3.) Tried that but water spilled out of the hopper and almost hit the filler tube. Bad idea.

4.) Great idea, but I really wanted to check out that check valve anyway. Clean the plug, remove and replace the needle valve, then back it way out and try to flood the engine. WHAT???? There WAS some gas in the line above the check valve. Still it wouldn't hurt to top off the tank just to be sure. The sound of gas dropping to the bottom of a tin tank told me I had just been playing with my Hercules for the last half hour not really trying to start it.

Amazing, just a little gas in the tank and she fired right up.
At least my Cushman X has a straight pipe that I can use to check the fuel level.
I reckon I will just ALWAYS top off the tank on the Hercules before I fire it up.

* How about long strips of cardboard? Or an old metal, flexible dip stick with something on the end to show liquid level? Maybe some paint or something semi-absorbent that will show the liquid level but that can dry out quickly to do other checks.

* Don't think it'd work on a Hercules. The first 90 is very sharp and then it would
have to fall down into the tank.

* How about a leather thong with a nut or large split shot on the wet end?

* Here's an interesting approach which worked for an acquaintance of mine down in West Virginia.
He drilled a series of 1/8" holes ½" apart in the side of the fuel tank casting starting near the bottom. He would be able to tell the level in the tank by determining the topmost hole that had fuel running out.
Hope that helps .... someone

* I've got it!!

A small round cork like is used for fishing. Tie a non-destructible string(?) to it and let the string hang out the filler hole. As the fuel level goes down the string gets pulled into the tank ... calibrate the string accordingly.

I should head for the shed.

* Seeing as how this is an enclosed tank, possibly we could design a little hammer that would go up and down the tank, tapping it. Or I could blow across the filler and listen to the sound ... like the little brown jug.
You think maybe I should get a tank FIRST??

With a bit of luck, by the time you read this, groundhogs around the United States will have emerged, failed to see a shadow and therefore spring will be on its way, meaning warmer sheds and an approaching engine season. Here in England, where we don't have the luxury of groundhogs, we'll just have to keep checking outside!


Site Index


Articles Index



©FBI 2003