Gas gauge readings inaccurate

[Bustedknuckle84]

I had to get towed in because i ran out of gas. :facepalm: The weird thing is the gas gauge was reading about a 1/8 of fuel remaining or tad bit less but still said i had gas left. Is the general rule not to run below 1/8" tank of gas. Or what is the best way to check your gas level?

 

[smokeonthewater]

Re: Gas gauge readings inaccurate

actually the "general rule" is 1/3 out, 1/3 back, and 1/3 reserve... since you know your gauge is off you can figure on keeping it above 1/2

 

[azboater2]

Re: Gas gauge readings inaccurate

Humm, are you in a lake where you can see the shores or open water? I boat lakes and of course smokeonthewater is right but I don't exactly follow that rule, however, I would never leave on 1/8 tank. I normally fill up every trip to the lake, and I have a fuel flow meter and I know pretty well how much is left. It's just not worth the chance. We ran about 60 miles up the Colorado and I got gas before the trip back just because I don't want to worry about fuel in any conditions. Storms whip up here sometimes and the ramps can get log jammed with everybody trying to get out at the same time. Me and the boy once spent 2 hours waiting out a storm just to dock in saftey, fresh gas, frest oil, and a good inspection the day before leaving and no worries. You should easly be able to change that gas sender though, but still if you filler up, you can check that off your list...

 

[UncleWillie]

Re: Gas gauge readings inaccurate

Carrying an extra 3 gallons "Just in Case" is never a bad idea.

I wish they would just put in a "Reserve" valve like many motorcycles have.
You run out of gas at 1/4 tank, (Hard to ignore!), flip the valve, and head for the nearest pump.
It has saved my Kiester more than once!


No need to replace the sender.
If you pull the sender and bend the float UP a little...
You can remove the Optimism from the gauge and make it a little Pessimistic.
It will read EMPTY when you still have an 1/8th.
Better than the other way around!

 

[Bustedknuckle84]

Re: Gas gauge readings inaccurate

so normally the gas gauge should read from 0 to full if you check in the water correct? or is their a certain procedure on land to check the gas? i.e. with boat on trailer level the boat and check the gas.

Knowing this will help me fix if their is really a problem.

 

[Bustedknuckle84]

Re: Gas gauge readings inaccurate

Carrying an extra 3 gallons "Just in Case" is never a bad idea.

I wish they would just put in a "Reserve" valve like many motorcycles have.
You run out of gas at 1/4 tank, (Hard to ignore!), flip the valve, and head for the nearest pump.
It has saved my Kiester more than once!

Haha i use to have a vulcan 900 and remember them days too. it saved my arse many times to lol. Im little spoiled now with my honda fury, it was a gas light..lol.

I like your thinking on the sender unit idea, sounds like the gauge is suppose to read empty when tank is empty when checking in the water.

 

[rallyart]

Re: Gas gauge readings inaccurate

Normally the gas gauge on a boat will be wrong most of the time. It is affected by list and pitch of the boat. Also, many boat tanks are very flat on the bottom which leads to a lot of fuel not being able to be picked up. Just assume it is wrong and your worries will not be as omnipresent.
My Grew would start to chug and run out of gas with a quarter tank. I would simply get the boat listing to port and you could make it to dock easily when you restarted the engine.

 

[azboater2]

Re: Gas gauge readings inaccurate

Well mama use to say “what ever floats you boat”, but I can never imagine deliberately setting a gauge inaccurately as a safety measure. But then some people set their clocks ahead so they can get to work on time, actually I've been thinking about that lately....but anyway, my thought was that sender may have a rheostat going bad anyway, so should be replaced. If it should have a bad spot on it already
then bending it is no assurance that it will still be dependable. As long as you have to take it out anyway, put an ohm meter on it and move the arm real slowly, and the resistance should change slow and smooth, if it jumps or drops off altogether then replace it. Never seen a v-hull with a flat tank but sure could be. The gauge itself has a damper circuit so it does not respond real fast to avoid some jumping around, but yes on average in the water loaded fairly even that gauge will be pretty close. Check with a local Bayliner dealer.

 

[UncleWillie]

Re: Gas gauge readings inaccurate

... I can never imagine deliberately setting a gauge inaccurately as a safety measure...

I never considered a fuel gauge to be an "Accurate" instrument in a boat or any vehicle.
The fuel gauge in my SUV will move 1/8th easily when going up or down a hill.
It reads FULL for the first 75 miles.
And when it pins on empty, it means I have 25 miles to find a pump.
(There are always 2 gals behind the back seat!)

The boat gauge is always bouncing around with all the sloshing.
All you can ever truly tell is "More than Half" or "Less than Half."
You get a different reading running Bow Up than running No Wake.
If it is going to be wrong, which it always is, I would rather it be pessimistic.
The Admiral starts reminding me at anything under a half anyway.

 

[azboater2]

Re: Gas gauge readings inaccurate

The Admiral starts reminding me at anything under a half anyway.

lol, I totally forgot about the Admiral, yea mine hates to see halfway come also. I guess I'm lucky because my boats have very accurate gauges. My bayliner does not bounce around, it is well dampend, and I have a fuel flow gauge anyway. The SUV, well sorry, but it also has a miles to empty computer and that thing is dead on. We don't have too many hills though, maybe thats the problem. No offence to the poster but I guess if my gauge showed 1/8 and I didnt get gas then I would deserve to run out.

 

[smokeonthewater]

Re: Gas gauge readings inaccurate

It may just be that your fuel pickup is a bit shorter than it should be too....
Of the 7 or so V-hull gas tanks I have actually seen there have only been 1 or 2 that weren't flat on the bottom

I don't always follow "the rule" myself. My 28'er has a 115 gallon tank and I am never more the 6 miles from fuel and never more than 1/8 mile from shore (river) but I start getting real nervous if it gets below 1/4 even though I know that it will run all the way down to empty and then some. No I never pushed it that low... I pumped out what was in the tank when I got it and added 5 gallons at a time... It would run with the first can but didn't start to register on the gauge till I had about half of the third can in it.

Yes it SHOULD read accurately and you can fix it if you want or you can just keep more in it.

 

[Silly Seville]

Re: Gas gauge readings inaccurate

^^^^+1

I've owned 4 V-hull boats and all had flat bottom tanks. My gauges are incredibly accurate, and that may be due in large part to them being Faria's. On my 30 gallon tanks, starting from dry, the gauge shows perfect quarterly incremental increases with respect to fuel added, i.e. put in 7.5 gallons, 1/4 tank shows. Another 7.5 gallons added, 1/2 tank shows. I guess I got lucky. When I want to run the tank dry for winter layup, I just circle the marina with the gauge showing empty for five minutes, then head for the dock!

 

[DuckHunterJon]

Re: Gas gauge readings inaccurate

1/8 on the gauge and you ran out - that's pretty accurate in my book. My boat is on fumes when the guage says 1/4. My Chevy truck guage will stay pegged full for 160 miles, then in 40 miles it drops to E. When the low fuel light comes on, I have 6 miles (ahem - tested this several times...)

You might be able to pull the sending unit and look at what the float is doing. If nothing else, now you know and it won't happen again (or so I tell myself with my truck).

 

[hog88]

Re: Gas gauge readings inaccurate

Don't rely on gauges!!! Fill your boat up, go run it for a couple of hours like you would normaly then fill it up again. Figure up your gph just like you would mpg in your car. Then just keep track of your usage that way, did it for years on my old boat, gas gauge never worked right.

I don't know how truthfull it is but was once told by an aircraft mechanic that ALL fuel gauges are only required to accurate when the tank is full.

 

[Bustedknuckle84]

Re: Gas gauge readings inaccurate

No offence to the poster but I guess if my gauge showed 1/8 and I didnt get gas then I would deserve to run out.

I don't know how long you have been boating but no offense their isn't gas stations "right around the corner" when your on the water. And I didn't leave the dock at a 1/8 tank remaining. I'm not sure if you read my op but I said i ran out of gas a, t 1/8 tank remaining. BTW if the gauge was accurate then i would have made it to the dock with gas to spare.

 

[Bustedknuckle84]

Re: Gas gauge readings inaccurate

I dont believe the sender is bad due to the fact it reads from full to now 1/8" tank. However, i have never ran the gas down to an 1/8 tank so I think i do need to pull it out for sure. I usually try to keep it around half tank.

 

[Home Cookin']

Re: Gas gauge readings inaccurate

I don't think I'd mess with the sender; just know that 1/8 means empty and treat 1/4 as the yellow light on the car dashboard that means head for more gas!

No boat gas guages are accurate, especially at the low end. there really is nothing to fix. You just have to know your boat. I have one (17 gallon tank) that stays on F until there is a quarter, then it shows 1/2. when it's an eighth or so, it shows 1/4.

Also filling a boat on the trailer, often the tank is not level, so it may not truly be full.

Although some disagree, I believe it is better for your fuel to keep the tank full anyway. Doing that, you are less likely to get caught short.

 

[UncleWillie]

Re: Gas gauge readings inaccurate

In defense of the OP.

He never stated that he left port with a non-full tank.
He indicated that he was headed in, and was almost home when the tank went dry at 1/8th.

His complaint is that the fuel gauge reads overly optomistic for his taste.
This may be due to a bad sender, bad gauge, or the factory, or others, may have just installed a generic sender.
These things are not traceable to the NIST!

He will either do nothing and live with the error.
Or level the boat, and calibrate the sender to the tank by adjusting the float. (MY bet!)
It is likely just a piece of cork on a bent wire. Not rocket science here.

 

[smokeonthewater]

Re: Gas gauge readings inaccurate

I'll say it again.... it MAY well be that the pickup tube is a bit short..... the tank may have actually had 1/8 of a tank and just wasn't able to pick it up

 

[cyclops2]

Re: Gas gauge readings inaccurate

NEVER EVER.....run a fuel tank dry of ANY TYPE of fuel !! Crap settles, water settles, insect parts, rust. There is not 1 good reason to get close to the bottom. Except to clog your fuel system & pay for a tow.
Another thing. A 1/4 of a tank will NOT stir up the crud as much or as long, as running a tank to dry.

Leave the bottom alone. Refill at a 1/ 4 if running near gasoline pumps.

Rich