2008 Lightning Gas guage not tracking levels correctly
 

All,
I just purchased a 2008 Fountain Lightning with 525's. 90 gallon tanks x 2. Livorsi gauges (analog) and Smartcraft.(digital). The Smartcraft readings are all digital and dead on. Unfortunately I don't see a gas reading on Smartcraft, so my guess is the 2008 factory installed Smartcraft does not have a gas sensor or did not have that capability in 2008?

so onto the Livorsi gas gauge... What happens is when you fill up 100%, the gas gauges go to past full and will stay at 100% for a really long time (weeks possibly based on how much I run) until the tanks are maybe 50 to 40 % (actual gas in tank) then all the sudden drops to 50% on the gauge or 25%-30% on the other). It does not show at all the progress from 100 to 90 to 75 to 70 % for example. Its either 100% or 50/40%. This is problematic if I am making a long run in a day and not close to a marina. Since the boat is brand new to me, I'm not sure what the behavior is from 40-50% actual to no gas at all in the tanks. I did notice that once it dropped, my starboard gauge read 50% and my port more like 25-30%. I am pretty sure that when they dropped, they dropped at the same time from 100% to either 50% or 25-30% depending on the side

How can I tell how much gas I actually have in the tanks? Could a module be added to the smartcraft or would that actually mean I would have to get a digital sensor somehow into the tank itself? (hmmm) Could it be a Livorsi gauge? (Im thinking not since both gauges do the same thing). Could it be a ground issue? Or is it most likely that the sensor in the tank is just a really inaccurate one by design?

Any insight is greatly appreciated

I would do a search on the Fountain Forum and you will get tons of examples of this. BUT my rule of thumb (learned the hard way)!!!

Fill it up! Now you know its full!!!

When it starts to move a little and "bounce" but stay close to full you have 3/4 tank. When it comes off of full you have 1/2 a tank or less. (start thinking about a fuel stop). When you are reading between 3/4 and 1/2 Stop thinking about filling up and GO fill up. When it gets to 1/2 or below your lucky if the engines are still running. This is just a rule of thumb that has helped me. I ran out at Lanier poker run and fried a starter thinking it had fuel. Lucky I didn't burn a fuel pump. Spent the rest of the day limping along on one engine. Ran it out of gas 100 yards from fuel dock. Now I fill up before every poker run to be sure. If I'm hanging at my local lakes I can go several times on a tank and not worry about it. BUT I ALWAYS KEEP IT IN MIND!!!

You are experiencing what every other Fountain owner has already with the gas tanks. The senders are located at the rear of the tanks, so with the boat in the water leaning backwards, those senders almost always read full until you really get much closer to empty. I've put brand new gauges and new senders in my boat and they still behave the exact same way, its not that equipment. Its just the design of the boat. My way of solving this has been to fill up, run the boat, watch how many hours you run and then refill again and check your hourly consumption. Then you can approximate how much gas you're burning on average per running hour and you can mentally adjust if you are wide open for longer periods of time. I have 105 gallon tanks. My experience has been that the gauges stay full until you're half full and then they start moving lower. when I'm between 1/2 and 3/4, thats usually an indicator that I have about 1/4 tank. Last time I dipped down to below 1/2, I had 17 gallons left in the tank.

Mine seem to behave the same way. However, they are reasonably accurate when the boat is on the trailer :picard1:

MJBoater My 38 EC does the same thing. I would suggest the fuel sender unit mounted on the fuel tank needs to be calibrated with the fuel gauge. If you talk with Livorsi or research the sender, it is designed to work with different depth fuel tanks. There are calibration screws in the top of the sender unit that is bolted to the top of the fuel tank. There are two screws to adjust, one for full and one for empty. You are supposed to fill the tank to full, then adjust the screw until the gauge reads just at the full line, not past. Then run the tanks low or dry and adjust the other screw the gauge reads exactly at the empty line. This sets the range of the gauge to match the depth of the fuel in the tank. My thought is that the Fountain Factory never fills these tanks to full, so they can never adjust the fuel sender unit as livorsi requires. I know this as I installed the same gauge and sender on a 357 Formula, cut the sending unit to my tank and adjusted accordingly. Worked perfect. I think once you do this adjustment, the gauge will show the progressive drop of gasoline in the tank. I will be doing mine soon and will let all know if it works.

I was wanting to run a WOT test and see my top speed..(since I wont have a ton of extra gas weight) .. its about a 20 mile run down and back. But I'm guessing at this point, I may run out of gas?

There is a Smartcraft gas reading. In the display where you can choose charts, chart gauges, etc, there is another level to set up your gas tanks. It will allow you to set an alarm when it gets to your desired level. The only problem with mine, is you have to fill it up every time and reset it. If you go put 60 gallons in or whatever and it's not full, it doesn't function. It will also give you all the full consumption figures. Google your model if you don't have the owners manual. Hope this helps.

I replaced all of my fuel senders with Livorsi AutoCal senders that do not require calbration. Still behaves exactly as I described above.

I think the big issue is the physical level at the sender never changes until the tank is half empty. Given the shape of the tank, and the angle of the boat, the entire sender is always "Wet" Make sense?

Different boat but mine read a bit better when on plain, the boat is more lever.

Have to agree with all the above, 20+ year multiple fountain owner here, know your rough mileage at fast cruise, know what she holds and do the math. Err on the side caution / safety and top it off whenever possible. I have spent the $ and they will never be accurate. Nature of the beast I guess.

This is my process, as well. Full means full - anything else means its time to start a refill plan.

fountain fuel guage
 

Why is a broken clock more accurate than a fountain fuel gauge,Becuase at least the clock is right twice a day.

Just plain neglect on Fountain's part.

I always thought it is because the tank is in the middle of the boat and shaped in a V.

No way will that be accurate unless you are on plain and then because of the shape still not linear.

Isn't that a issue with any V hulls? Or do others have flat bottom tanks?

My dad and I were talking about this last weekend. I think it's a common problem depending on how the boat sits in the water (sitting still vs on plane). He has the same issue on a new Chris Craft Corsair. The only accurate way in my opinion is with Smartcraft or similar digital gauges that measure how much fuel you've added and consumed.

Hello i am new to the site here and i was wondering if anyone had the correct part number for the fuel tank sending units on a 1997 35 Lightning. Thanks for all of your help

My solution to the fuel gauge level problem was to have 2 custom 30 gallon saddle tanks installed so I don't have to worry about it any more. Couldn't think of a better nor more practical failsafe!

Having owned a couple Fountains myself, the rule I follow is ....

when she shows 1/2 fuel begin to think about fuel!

when she shows 1/4 fuel be very close to a fuel dock, or have a paddle!

it is just the way this chit works, you can try to out think it all you want. not going to work. Learn how your boat responds to the gauges. Every boat is different, had a Velocity that when one tank ran out, engine died, the other would idle along for 20 minutes, don't ask how I figured that out. But a Fountain that had gas towed me back to the dock.

Hey thanks for the info! I have heard the same and you are about spot on! My port gauge isn't registering anything but the gauge works so indef need to replace that one but the starboard motor does due to being out of gas when it was showing between 1/4 and 1/2 on the gauge. Figured I would replace the starboard while doing the port since it was that far off

As many have mentioned it's just the design (flaw) of the tank and the boat. With SmartCraft you have a huge advantage - fuel burn. Use it to calculate how much fuel you have burned - just remember to calibrate it each time you add gas.

Only pitfall with this strategy is you don't know how much of the available fuel left that your motor can actually pick up. Using Smartcraft on one particular trip showed we had burned 65 gallons per side, then the motors ran out of fuel. After getting to the fuel dock, the boat took 65 gallons per side to fill. That was not a fun way to learn that either the tanks are only 65 gallons instead of the advertised 75, or that the last 10 or so gallons can not get picked up by motors.

Now I know, just like we all know how the mechanical fuel gauges perform so we plan accordingly.

OK thanks for all of the info!! I guess i need to be looking for the fuel dock when i see a half tank! Another quick question for you guys. What king of water temps are you guys seeing or do you feel is good for a set of 540s? The previous owner wasn't running any thermostats and my water temp gauges weren't registering anything past 100F. I put a set of restrictors in it this week but unfortunately with the weather here in Ohio and life being too damn busy i have put the boat away for the season so i wont be able to see what kind of temps i am getting until spring. Can anyone share what kind of water temps are good/ normal around cruising and wide open? Thanks for all of the help! You guys will prob be hearing from me more and i am learning more about the boat and trying to get things dialed in.