Fuel Gauge Whoas

[Peter B]

The fuel gauge on my E 30+ now suddenly gives me a false reading beyond full.
I cleaned the electrical connections - the sender, + & - on gauge, sender on the gauge and light. No difference.

I decided to order a new gauge and sender but I still feel like I'm missing something.
Any words of wisdom for me?
Thanks

 

[Loren Beach]

Do you know the brand or model of the sender? It's age? Maybe just post up a picture of the top of the tank where it's installed.

 

[Peter B]

On the tank there's a single wire hooked to a terminal in the center of the circular 5 bolt sending unit.
The wire goes straight to a terminal on the fuel gauge. Also on the 2" gauge are terminals for positive, negative, and light.

 

[Frank Langer]

On my 1984 E30+ I also have a black ground wire on the tank sender, off to the right a bit, only visible when I removed the floor board to replace the tank. That black wire was almost disconnected/chafed through, giving me eratic readings. I'm guessing you have a similar problem with that ground wire.
Frank

 

[shard7]

FYI, the sender has a variable resistance to indicate fuel level, 220 ohms at empty and 33 ohms when full. So if it's showing more than full, that may suggest a short (0 ohms) in the sensor or its wiring.

 

[Tin Kicker]

FYI, the sender has a variable resistance to indicate fuel level, 220 ohms at empty and 33 ohms when full. So if it's showing more than full, that may suggest a short (0 ohms) in the sensor or its wiring.

Probably this with one of those old mechanical arm gauges.

Replacements are cheap and easy to access.

 

[shard7]

Yup, quite easy to replace (did mine recently). I waited until the fuel level was down to 1/4 to avoid fuel spill issues when the sensor is out. Also, consider sticking with the conventional arm type sensor from Moeller Marine; ones where the float slides up and down a straight tube will only fit tanks with flat bottoms (I found out the hard way that my E27's tank has a ridge molded in right below the sensor opening).

 

[Peter B]

Thank you one and all. Your responses where all read and appreciated. I inspected the wiring and replaced the sending unit. When I had the old sending unit out of the tank I noticed that the fuel was to the brim of the tank. Perhaps it isn't a false reading. Perhaps the bloody fuel tank is full!

Her Universal M18 is the most economical engine I've ever encountered so burning through the diesel will take a while to do. Hopefully the gauge will move accordingly.
Again, thanks for your advice.

 

[jav317]

Has anyone wired in an extension to the fuel gauge on the tank? Lifting the mattress in the aft cabin isn't very conducive to checking the fuel level.

 

[supersailor]

First, the fuel gauge is wildly inaccurate. The standard gauge is linear and the bottom 2" of my tank holds almost 2 gallons and the top 2" holds 18 gallons. This essentially makes the gauge useless.

Second, you should never trust a gauge when you can't pull over to the curb and flag Triple-A. When I was flapping around in the sky, it was pounded into you to dip the tank prior to every flight. Running out of fuel was usually fatal so don't trust a gauge that can fail. I tend to think in terms of running out of fuel in the middle of the Dent Rapids or some exciting place like that.

I paid to have my tank calibrated at 2" intervals and that info programed into a programable sensor. I now can read that at the tank and the chart table. More importantly, I have kept track of my hours and amounts of fuel since I bought Terra Nova. She burns 4.1gph. [Bob corrects this typo in Post #17] With an accurate tank capacity and burn rate, it is easy to calculate hours at refill. I post that on the instrument panel over the Chart Table. Because my tank was calibrated, that info is now free. Unfortunately, only the 34 has that tank.

I realize that that is not very important for those of us that pop in and out of the same harbor and take an occasional weekend cruise. For those of us who take serious cruises in the great north, running out of fuel could be fatal.

Unfortunately, I am away from home and not sure of my return date. If you are really anxious, I will attempt to retrieve the info remotely.

 

[Kenneth K]

Has anyone wired in an extension to the fuel gauge on the tank? Lifting the mattress in the aft cabin isn't very conducive to checking the fuel level.

An electric fuel gauge is usually located near the engine panel.



Or, you could move it to the nav station / electrical panel if you prefer it in the cabin. Either way, both (1) the sender wire from the tank and (2) the wires that power the gauge will have to be lengthened.

 

[Loren Beach]

From past threads on the subject it appears that a lot of experienced owners simply keep a small notebook handy with entries for gallons put in, and hours read from the Hobbs meter. These smaller diesels use little fuel, like a half to 3/4 gallon an hour.
Sometimes Occam is correct !

 

[jav317]

First, the fuel gauge is wildly inaccurate. The standard gauge is linear and the bottom 2" of my tank holds almost 2 gallons and the top 2" holds 18 gallons. This essentially makes the gauge useless.

Second, you should never trust a gauge when you can't pull over to the curb and flag Triple-A. When I was flapping around in the sky, it was pounded into you to dip the tank prior to every flight. Running out of fuel was usually fatal so don't trust a gauge that can fail. I tend to think in terms of running out of fuel in the middle of the Dent Rapids or some exciting place like that.

I paid to have my tank calibrated at 2" intervals and that info programed into a programable sensor. I now can read that at the tank and the chart table. More importantly, I have kept track of my hours and amounts of fuel since I bought Terra Nova. She burns 4.1gph. With an accurate tank capacity and burn rate, it is easy to calculate hours at refill. I post that on the instrument panel over the Chart Table. Because my tank was calibrated, that info is now free. Unfortunately, only the 34 has that tank.

I realize that that is not very important for those of us that pop in and out of the same harbor and take an occasional weekend cruise. For those of us who take serious cruises in the great north, running out of fuel could be fatal.

Unfortunately, I am away from home and not sure of my return date. If you are really anxious, I will attempt to retrieve the info remotely.

Thanks for your input. I have always monitored my fuel by gph use. I only burn about 1/4 gal per hour. I was looking for just another way to keep an eye on it.

 

[paul culver]

I use engine hours, allowing 1 gal/hr for the Atomic 4. It always errs on the safe side.

 

[Martyn]

Thanks for your input. I have always monitored my fuel by gph use. I only burn about 1/4 gal per hour. I was looking for just another way to keep an eye on it.

I burn ¼ gallon per hour and use the notebook method as well. Gauge has not worked since I bought the boat.

 

[nquigley]

First, the fuel gauge is wildly inaccurate. The standard gauge is linear and the bottom 2" of my tank holds almost 2 gallons and the top 2" holds 18 gallons. This essentially makes the gauge useless.

Second, you should never trust a gauge when you can't pull over to the curb and flag Triple-A. When I was flapping around in the sky, it was pounded into you to dip the tank prior to every flight. Running out of fuel was usually fatal so don't trust a gauge that can fail. I tend to think in terms of running out of fuel in the middle of the Dent Rapids or some exciting place like that.

I paid to have my tank calibrated at 2" intervals and that info programed into a programable sensor. I now can read that at the tank and the chart table. More importantly, I have kept track of my hours and amounts of fuel since I bought Terra Nova. She burns 4.1gph. With an accurate tank capacity and burn rate, it is easy to calculate hours at refill. I post that on the instrument panel over the Chart Table. Because my tank was calibrated, that info is now free. Unfortunately, only the 34 has that tank.

I realize that that is not very important for those of us that pop in and out of the same harbor and take an occasional weekend cruise. For those of us who take serious cruises in the great north, running out of fuel could be fatal.

Unfortunately, I am away from home and not sure of my return date. If you are really anxious, I will attempt to retrieve the info remotely.

?? "She burns 4.1gph" ?? (maybe 0.41gph?)

 

[supersailor]

Good point! 0.41gph. I'm a little stressed, I guess. I almost always have the main up, so it helps in overly light winds. I never power into strong winds and chop. That's what I have an Ericson for. Sailing!

 

[bgary]

From past threads on the subject it appears that a lot of experienced owners simply keep a small notebook handy with entries for gallons put in, and hours read from the Hobbs meter. T

Yup. I keep a a "deck log" with number of hours since last fill-up. I know that - on average, at 2300 rpm, I use a little under 0.4 gallons per hour. So when I've run 30-35 hours, I know I'm down about 12 gallons.

I stick the tank through an inspection port periodically, just to confirm, and know that (e.g.) when the fuel level is down 5" from the top of the tank it takes about 12 gallons to fill.

Edited to add - the stick-test is NOT linear, due to the shape of the tank. 5" means about 12 gallons down, but 10" down is probably (*) more like 15 gallons down, due to the tapered shape of the tank.

(*) I've never let it get much below half a tank, but....

$.02

 

[nquigley]

For the last ~4 months, the needle of my fuel gauge jumps wildly back and forth between 'empty' and the correct level after starting the engine, then flicks between the correct level and levels about 15-20% lower after running for about 15 min, and finally is stable at the correct level after running the engine for about 30 min. What's the likely diagnosis? (and possible cure?)

 

[Kenneth K]

What's the likely diagnosis? (and possible cure?)

If it always clears up after 30 mins, maybe that's how long it takes the little bulb inside the gauge to heat and dry the moisture in the gauge or on the terminals.

Loose or corroded grounds are also always worth considering.