How to find fuel level in aluminum tanks?

Floscan is a fuel meter. The only processor it contains is to count the sensor pulses and remember how much fuel has been consumed.

Northstar is a fuel management computer which they bought from Navman. When plugged into a GPS it gives you a wide range of reading, calculations and display options.

Both serve their purposes pretty well. They key to their success is their data source which are sensors spliced into the fuel lines. The SmartCraft uses the ECM feeds which can also be read by automotive scanners. The problem of using just a scanner is that the really useful information such as mpg require a GPS feed to calculate.

-John
 
A little OT, but please keep the EFI and Fuel monitoring info comming.
I'm learning something!

The Smartcraft System w/system view is hooked to the GPS, but I don't know if it gets the distance info from that or the paddle wheel, and I doubt the pitot tube.

My version is probably 3-4 years old now and I wonder if they added more info and tools since then.

Ron, My mother named me William and only used it when she was mad. Freinds call me Bill!
I don't often write Bill Miller because I don't like the initials. :)

Great idea with tapping. I tried my knuckles a few times, but didn't think to use my wedding ring that's handy! The tank is 21" tall and I can get to enough area to tap. Although I'm not sure my hearing could tell the difference. Maybe a stethescope (I have one) would help amplify the tome difference.

I'm not sure a snake would show enough clarity at the fuel level line.
You did give me an idea. I use a water level to level floor pads to do alingments on my car.
I have a tiny valve on the tube (Also one of those pinch things used on an IV drip). If I can get a small tube down the fill, I'll push it to the bottom with the valve open, close the valve and draw the tube back out. The fuel left in the tube will show the tank level.
The stiff tube I stick in the dip stick hole to vacuum the oil is probably about the right stiffness.

Frank, welcome.
Come-on, we are still at the brain-storming stage. Your caution is welcome because although I don't want to take any big risks, others might. Your info on the tanks is very helpfull. Do you have ideas that might work? Jump on board and help solve the puzzle. (Safely!)

So, if I was to unscrew the fuel outlet fitting on the top of the tank, might I be able to stick something like a dipstick down the tube? I think there is enough acess at the top.
 
I'm heading down to the boat for the weekend. I'll try a few of the safer ideas and report back.

I have to cross the bay bridge. There has been so much hype about traffic jambs, but the last report said it was only backed up 1/2 mile. That's normal.
I hope everyone didn't take their suggestion to go down later this evening, like me.

Thanks for all the suggestions and ideas!
 
I happen to have a thermal gun, and also have some screwed up gas gauges after an hour and a half surprise micro burst storm put me and my helm into 6' waves a while back. I'll try shooting the sides of the tank tomorrow morning when it's "cool" (85 instead of 95). That could potentially be the safest thing mentioned. I have the Navman flow gauges, but they do not register well when running under 2000 RPM for extended periods, like all this summer...... There's just not enough fuel flow (did I just say that out loud!?)
And that is with 380 HP Mag MPIs.
 
I happen to have a thermal gun, and also have some screwed up gas gauges after an hour and a half surprise micro burst storm put me and my helm into 6' waves a while back. I'll try shooting the sides of the tank tomorrow morning when it's "cool" (85 instead of 95). That could potentially be the safest thing mentioned. I have the Navman flow gauges, but they do not register well when running under 2000 RPM for extended periods, like all this summer...... There's just not enough fuel flow (did I just say that out loud!?)
And that is with 380 HP Mag MPIs.

Thanks, so two of us are in the same boat...
I played with a few things yesterday.
I bought a IR thermometer at harbor freight $35+/- but left it at home. (Doh..)
I wanted one anyway for work on my car.

I learned a lot yesterday by messing around.
1st, my tanks have unused bungs on the rear top of the tanks that are accessible from the bilge. They have a tube that goes down to about 1/4" of the bottom of the tank. They have an aluminum plug with pipe threads. (opened with a 7/8" wrench) My guess is that it is 5/8 or 3/4" pipe fitting.

I was able to stick my small tape (aprox. 1/4" blade?) down the tube and hit the bottom in a straight shot. The hook on the end of the tape caught the end of the tube on the way up. It did come out after a little giggling.

With this extra bung easily accessible, I am considering draining my tanks this winter.

The tape was not the most telling thing to stick in the tank, but it allowed me to confirm that there was about 12-13" of fuel.

With that estimate, I marked a pencil line on the side of the tank.
Next, since I didn't forget my stethescope, I started playing with that.
(This is an automotive stethescope, not like the doctors use. The ear part is the same, but the other end has a thin rod which is used to help isolate noises such as bad bearings. I've used it on leakdown tests to determine where air is leaking out of combustion chambers.)
This amazingly simple tool amplifies sound and really helps you pinpoint where it is comming from.
My first attempt was bas-akwards. (I placed the tip of the stethescope in one spot and tapped the tank with a wrench up and down the side of the tank. The sound didn't change much if at all.

Second method, alomst an afterthought was to tap the tank in the same place and move the stethescope. What I found was pretty cool, and it makes perfect sence.
With the stethescope above the fuel level, you could hear an echo of the tap bouncing arround inside the tank, with the stethescope below the fuel level, the echo seemed attenuated by the fuel. (slightly lower pitch maybe and not as much echo).
Once I figured this out, I could move the stethescope up and down, narrowing it down to the level of the fuel. I think this works pretty good and feel comfortable withing 1/2-1".

I'm not sure if it would be harder or easier to hear at different fuel levels.
I recall (from when I was a kid) an old mechanic sticking the handle of a screwdriver to his ear and listining to different parts of an engine. So a screwdriver may be a great substitite since I keep tools on the boat. I wonder if a drinking or a shot glass might be better!

So this one works, cheap and simple. It's just that the change is sound is not extreemly easy to detect.
I think if the IR gun works it may be easier.

I went to the hardware store while running erands. I bought some 3/8" tube. Not the clear plastic tube, but its more translucent, white and stiffer, like the tubing used on refrigerators ice makers. I stuck this down the bung hole and put my thumb on the end and pulled it back out. I could clearly see the fuel in the tube. This helped me confirm my measurement with the tape. I'm going to make some marks (Don't know if a sharpie will wash off with the fuel) or notches on the tube for the next time and then I don't need the tape anymore. This is not exactly the easiest, or safest, but it is fairly precise.

More on the other ideas later.
 
I tried the IR gun this morning on 2 boats. One was diesel, that I had run yesterday for an hour or so. It was still warm in the engine room. The other is gas, and has not been run lately.

When I first started all I could get was a 1 degree change over the height of the tank, from 94 to 95 degrees. Over time, even that went away (I'm guessing the engine room was equalizing from having the hatch open. The 1 degree could have been from the lower half of the tank being closer to the engine. the port side showed no difference across the tank.

The gas boat showed no difference across the tank, and they were at about 84 degrees. It was a fairly humid day, and not much variation from the night to the day.

So, my conclusion is that this will not be a reliable way to check, unless perhaps there is a more significant difference during the winter, when I have more drastic temp changes. (You know, 10 degrees....)

An obvious word of caution for you is make sure you give your engine room time to rid itself of fumes from your open tank, and gas covered hose before running.

I may try the hot water bit to see if I get a sweat line.
 
Couldn't really hear a difference by tapping. Probably from standing in front of Marshall 8x12" stacks for years......
 
standing in front of Marshall 8x12" stacks for years.

ah, that explains the dolphin playing the red strat (pre CBS, i'm sure)!

Ron, My mother named me William and only used it when she was mad.

copy that. very few people call me RONALD.
 
On the same theme - no hijack intended - does anyone know what kind of senders I have on a '98 400DA with Cats?

One of mine failed recently. The guage is OK - I connected it to the other tank and it works. The port guage started showing below empty after a recent fill up??

I have located the sender port so now I will need to know what type I have and whether it can be repaired or not..

Does anyone know before I go to SR?
Thanks, Warren
 
My fuel gauge works but I no longer use it. The fuel flow meter uses your tank capacity and fuel used based on what was required to last refill the tank along with the distance traveled from a GPS sensor to calibrate your fuel line sensor. Thereafter it is very accurate as a fuel gauge showing gallons remaining or range at current speed. Trick is to always remember to tell it how much fuel you added at fill-ups.

But its best use is displaying real-time GPH and finding your most efficient cruise speed and trim settings.
 
ah, that explains the dolphin playing the red strat (pre CBS, i'm sure)!
Funny, I just saw this again after 11 years. Go find the thread on CSR about showing off your guitars. Pretty active right now. Candy Apple Red is the sweet spot for me, although the Avatar is clearly Chevy 350 block red. I've played a bit. Still do, when the old folks home gets out on the town, and cuts us loose.
 
HaHa. I saw the guitar thread and passed on it. But now you inspired me to go and post my "collection!"
 

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