Fuel Gauge Sender Unit & Tank Weirdness

HydroCanis

So the last thing I noticed wrong last year was the that fuel gauge stayed on F even after burning probably 10-12 gallons (of 64). I took it out the first time this year and probably burned another 6-8 gallons, and it still read F. Yesterday I pulled the send unit out of the tank. It has a pivot at the top which presumably controls a variable resistor, and a thin steel rod onto which is a rounded-end rectangular float. I tried moving it along it's range of pivot and the gauge registered somewhat appropriately. It could have been stuck and me removing it freed it. Or maybe it was working correctly. The weird thing is that I reckon the tank should have been down at least 15 gallons, but it was full to the top of the sender unit hole. So I'm thinking that 1) maybe when I filled it it was full almost to the filler cap (this is before all the emissions hosing), 2) the fuel expanded a little while the boat sat in the sun, and 3) the bottom of the tank sagged a little when full, allowing more fuel to go in, but unsagged as some fuel was used. Does any of that make any sense? I siphoned out a couple of gallons before my siphon bulb failed, and the level went down about that much. Wife suggested somebody borrowed the boat and refilled it. I wouldn't be that lucky. Another possibility: water got in somehow. There's no visible separation in what I siphoned out, and the engine ran well a couple of weeks ago and started and idled fine yesterday. Thoughts? Best way to check for water aside from examining the little separator/filter inside the OB cowling?

Ernest_T

I experience something very similar with my 217 SD.  The fuel gauge seem stuck on full for a long time after a fill up, then it finally begins to drop.  Once it shows 1/2 tank it drops like a rock.  Because of this, I fill the tank when the needle reaches the 1/2 full mark, and I can typically put in nearly 40 gal. of fuel (my tank is supposed to be 52 gal.).  

After contacting the dealer, he told me it had to do with the shape of the fuel tank.  He said the tank has a wide section at the top, and a narrower shape at the bottom.  The sender reads the level in the tank, but not the actual amount of fuel.  The result is that you get an initial slow drop in the fuel level in the wide top part of the tank (since there is a lot more fuel in this section), then when the fuel reaches the narrow part of the tank you get a quicker drop in the level.  

Hope this makes sense.  It seems to explain what I see on my boat. 

HydroCanis

It does, thanks, and I thought it seemed a bit that way earlier last year. Good to know I wasn't just imagining things. Because of that, it seems to me the only way to get a realistic reading would be to install a FloScan or something similar (which I'm considering). Don't recall reading where a Hurricane owner did that, but it doesn't sound too bad as long as I can splice into the fuel line before it exits to the transom.

caseynettles

I just put a fuel flow meter in this past Friday and used it this weekend...I love it...I put 30 gals, the instrument allowed me to see how much fuel is used at WOT and at cruise.  It also counts down the gallons remaining, total gals used and GPH in real time.  So for both Sat and Sun out all day I used 17 gallons, which is nice to know because like you said, once the fuel guage hits 1/2, its time to think about getting some fuel quick.  I will post pics when I get home.  I actually got the Northstar F210, they are really hard to find and it seems that FloScan has the corner on the market for some reason.

HydroCanis

That sounds great—exactly what I'd like—but when I posted that I was somehow under the impression I could get a sensor and gauge both for under $200. I'm not seeing anything close to that now—more like double that. I'll probably just have to be jealous for a while.

bshippjr

Ernest, thanks for explanation.  My 217 does the same thing and I always thought it was just a typical inaccurate fuel gauge.

caseynettles

here is the picture of the one I installed, they used to be quite popular, sold for around $100 and went by several names for the same basic unit, NavMan, NorthStar, I think Faria and Teleflex even put there name on it as well.  Look on Ebay, that is where I got mine new in the box....I did have to get the head unit and transducer in separate auctions for a total of $300 which seems the going rate for these, the newer FloScans are even more $$ like you said but they do allow you to connect to your GPS and get a MPG reading in real time if your GPS has an I/O port.  Good luck I hope you can find one, they are a little pricey but they do give you some peace of mind which is an easy selling point to my wife.

HydroCanis

Thanks. I'm sure it's nice to have that peace of mind.

On a side note, I have that same style of Faria gauges (which I like) and was considering adding a compass, but it's not available in that style. Did you ever add any Faria gauges to the factory suite?

caseynettles

When I purchased the boat the tach did not match the rest of the factory gauges, was a new style bright white gauge, I purchased a tach and speedo (had to buy speedo too because the original older factory speedo did not exactly match the new tach) from here http://bpi.ebasicpower.com/mm5/merchant.mvc?Store_Code=eBasicPower&Screen=SRCH&Search=Faria%20Euro%20Beige%20&psrelevance=name,descrip,malterms,oem, I was hoping to find a water pressure gauge to match but I do not think they make one, but I am considering adding the water temp.  So the speedo you see in my pic is new.

caseynettles

I did replace all the incandescent bulbs with LED which gives them a really nice look at night.

cjjjdeck

Hey casey, maybe you can snap a picture of it so we all can admire the glow!

caseynettles

Will do CJ, I still need to finish my SS dash project.  I think I might redo the main dash with a thicker black edge trim, not sure though.  The middle dash piece is going to be tricky getting the exact alignment with the circuit breakers, not much room for error behind the dash.