Fuel gauge NOT accurate: how to calibrate?

[Mariner]

Yesterday was an interesting day. I found out the hard way that the fuel gauge on our '03 36' ET is nowhere near remotely accurate. It had dropped to about 3/8 of tank when the generator and engine sputtered to a stop. Given the weather at the time, I was immensely fortunate that it chose to do so inside the harbor, mere minutes from the marina. Had it done so just five minutes earlier I would have been dead in the water in the middle of the treacherous Tacoma Narrows in the dark in driving rain and zero visibility with three commercial tug and barge combinations bearing down on me.

Any idea how you calibrate a fuel gauge? I'm not at the boat right now, so I don't know the brand or anything about it, other than that it's electronic and there is a switch that allows you to read the level on each tank from one gauge. It's an analog needle.

[Tuxedo]

The sender is probably a lever arm type. You can shorten the lever so it goes all the way to the bottom of the tank, but it will likely fail sooner than later.

If I was going to that trouble, I'd replace it with this.

http://www.wemausa.com/tank_sensors/tan ... ensors.htm

(Actually, I have).

BTW, the one time I ran out of fuel, I was able to limp home at slow speed because the fuel pickup is at the front of the tank, so with the boat off plane, it was able to pick-up some fuel.

[tomcat rio]

couldn't hurt.
...
http://www.floscan.com/html/blue/generators.php
..
it computes fuel burned in addition to actual fuel flow. independent of the level gage/sender.

[Mariner]

Those are both very good suggestions. I'm curious to find out what kind of senders are in the tanks currently. The boat has a fuel flow gauge built into the electronic engine display which is programable. I will have to see if it can be programed to tell you how much fuel has been burned so far on a given trip or fill-up.

I'm very concerned by the fact that BOTH tanks were so inaccurate. I can only assume that it's either a problem with how the senders were originally installed in each tank, or with the calibration or function of the gauge itself.

I consider running out of fuel to be a very rookie mistake; the kind that an experienced guy like me doesn't make. But here I have gone and done it. Perhaps I shouldn't trust my instrumentation quite so blindly.

[jcollins]

Mariner,
Don't beat yourself up. Even I <smile> have run out of fuel. Like you I was close to home. I called a friend and he brought out 10 gallons.
But, that was gas, not diesel. When I purchased this boat the previous owner told me "change your filters and never run out of fuel". So, how hard is it to restart?

John

[Denis]

Just currious, are you sure that you ran out of fuel and it was not something wrong with your fuel pump?

[DougSea]

I'll be interested in hearing how you handle the calibration. On our maiden voyage I was VERY impressed with how slowly the boat burned fuel - until I was headed into New York Harbor, with no fuel docks around, and the gauge plunged! Made for some serious 'pucker' time!

I have a Navman chartplotter on my outboard (which I still own - call me Fleet Admiral Doug ) that I added the fuel flow transducer to. It is so much more accurate than the tank gauge. Adding a Navman or Flowscan to the Albin is high on my list of things to do - but I'd still like the tank gauge to be more accurate - just like I have a compass even though I have a GPS it's always good to have a backup!

[AlMar]

I had a Navman on my last boat, but haven't been able to find one that monitors Diesel. Have you seen one? The Floscan is sweet (7000 series) but the best I've found so far is about $800 bucks. My bamboo stick is working pretty well in lieu of that much cash
AlMAr

[Veebyes2]

I've been victim of more than one or two fuel sender failures. How come marine ones are so unreliable? In almost 40 years of vehicle ownership I've only had one failure. In 20 years of boat ownership there have been 5 failures.

The adjustment is most likely through the movement of the float on the arm. If setup properly the genny pickup is higher in the tank than the propulsion engine. This is so you can't suck the tank dry with the genny & have no way of getting home. How high above the engine intake is the question.

The failsafe method of not running out of fuel is to keek a written log of engine hours & fuel purchase. The average will most likely be very consistent from year to year.

An even more basic method is being aware of how the boat floats on its lines with various known amounts of fuel & water aboard. I have a difference of almost 2" between tanks 1/4 full & full at the transom. Full is right up to the transom boot stripe.

Wish I had access to the top of the tanks to get a dip stick in them. A stick does not lie.

[AlMar]

Veebyes2, I think we have the same model. If you open those little doors in the cockpit where the rod holders are, you have a clean access to the vent hose. We just pop them off, and put our precalculated dipsticks in (provided by the previous owner), and have a pretty accurate site gauge. We still leave the vent lines snug, but they've never come off.
AlMar

[SpaceCoaster]

Have any of you ever considered installing a sight gauge? That's the route I might take one day assuming I have the space for one. I had two installed on a 36' trawler that didn't have any sort of fuel gauge.

Basic configuration is two valves aligned vertically on the side of the fuel tank with a clear (polycarbonate?) tube running between them. With the valves open the fuel enters the tube and you can see how much fuel is in the tank. My diesel engine mechanic installed them for me.

You can't go wrong with these.

Jorge

[Veebyes2]

Almar, I'm not a fisherman so I seldom open those doors. In fact I think the latches are siezed both sides. I'll try to have a look this weekend.

[jcollins]

I had a Navman on my last boat, but haven't been able to find one that monitors Diesel. Have you seen one? The Floscan is sweet (7000 series) but the best I've found so far is about $800 bucks. My bamboo stick is working pretty well in lieu of that much cash
AlMAr

Almar,
I was looking at boatfix.com last night.
http://www.boatfix.com/cart2/Scripts/pr ... duct=10008

Should be around 400.00

John

[AlMar]

At that price I'd buy one today BUT, since it's for I/IO/OB, I'm guessing it's for a gas engine. Haven't seen many OB diesels yet. But tks, and keep on looking.
AlMar

[DougSea]

Here's a write-up of the Navman diesel flow gauge from a New Zealand site:

http://www.discount-marine.co.nz/catalo ... ts_id=3029

I did find it at this US site:

http://www.northeastmarineelectronics.c ... rodID=1013

but their price seems a bit high. Didn't have time this morning to check with my usual guys. I've had good luck with ByOwnerElectronics, located down in John's neck of the woods. They've always given me good prices and deals on shipping.