2014 Seneca fuel gauge

[rvsparky]

Any one else having an issue with the fuel gauge ?? My low fuel light came on and I filled both tanks for a total of 41 gals. Would think that it should have been reading just under 1/2.
Any input ??

[LSA376]

Yesterday the fuel gauge indicated 1/4 tank as I was only able to add 34 gallons total between the two tanks. Not sure how accurate the gauge is....

[greyhawk885]

did you add both tanks at the same time?

[RULazy2]

In the year long trek we made to actually pull the trigger on our own Seneca, I ran into this problem a lot. The main answer was to take it to FL and make a warranty call. The answer is vague but has something to do with the fuel level sender in the tank. Most people indicate they just live with it and keep good logs on their fuel economy. Apparently, the RH tank holds all the fuel level sensors and are common parts to the M2 series of trucks and they do not calibrate the sensor to the tank it is married to all the time. Hope it helps.

[rvsparky]

Yes.

[rvsparky]

Good response. The Freightliner service manager is thinking the same thing

[Emily7271]

Originally Posted by rvsparky

Any one else having an issue with the fuel gauge ?? My low fuel light came on and I filled both tanks for a total of 41 gals. Would think that it should have been reading just under 1/2.

Any input ??

Oh, yes! We had the same problem with a brand new Melbourne last year. A connector had pulled apart under the cab. Have them check all the wiring connectors under the extended cab and RV. That is what finally fixed our gas gauge after trying everything else for two weeks!

[Mr.Oz]

Mine does the same thing. Low fuel light and 45 gallons filled both tanks. Have to get it checked out.

[greyhawk885]

Thoughts. 2 round tanks max fill when empty 62 or there about. Fill caps are not on top of tanks loss of about 12 to 14 gallons. Sensor in small tank. Holds 28 gallons. Large tank holds about 34. But since it is About 15% larger and equalizes with gravity it will have 4 or 5 gallons more remaining when around 1/4 on gauge. In this thought process 1/4 or around there would take 21 in right tank and about 20 22 in Left. That is how mine works out.

[greyhawk885]

By the way you need to fill both tanks at the same time at a truck stop type fill with a pump on each side.

[Mr.Oz]

Did some research and spoke with Freightliner. The rig pulls from the drivers side tank which is where the sender is. The tanks gravity feed together. This is what Freightliner told me. To make the gauge function properly was told to always fill the passenger tank first. Seemed doubtful to me. So I tried it with just a short trip and the gauge seemed accurate.

We just took our first trip of the year. Filled up, passenger side first and off we went. Stopped after 420 miles and was reading barely under 1/2 tank. Filled up with the passenger tank taking 20 gallons, drivers tank exactly 15 gallon. Both fill-ups I let the foam settle and filled exactly to the bottom of the neck to be accurate. So right at 12mpg with the cruise set at 64mph, 95psi in the tires. Not bucking any wind or hills.

Filled again the same way and went another 70 miles and the gauge just came off full. Looks like our capacity is right at 70 gallons? So try filling the passenger side first and see what happens. So far so good with us.

[Watt]

Mr. Oz, did the passenger tank gravity feed to the driver's side while filling the passenger side?

[Mr.Oz]

Originally Posted by Watt

Mr. Oz, did the passenger tank gravity feed to the driver's side while filling the passenger side?

I think it's a slow feed. Could not tell in the short time of filling. There may be some sort of valve that opens or releases by filling the passenger side first. I'm going back to Freightliner mid May for a passenger power window motor. I'll ask to see a fuel diagram to understand what is going on.

[Watt]

Thanks, I'm also arranging to take ours to Freightliner for cab a/c work and will ask about the fuel system.

[Watt]

Had a chance to fill up with diesel today. Mr. Oz's process worked great; filled passenger side 1st with 18 gallons, then driver side with 18 gallons. First time my fuel gauge has shown full tanks. Still planning on discussing the system with Freightliner next week.

[Mr.Oz]

Cool.... Let us know how it registers as you drive. Mine has been working perfect.

[Watt]

Will do, only drove 60 miles from Flying J to home. Gauge showed slightly less than 1/8 used at 65 mph on interstate and farm roads. I did notice as we accelerated the gauge would drift, but then level out. I'm guessing it's due to fuel movement in the tank.

[Mr.Oz]

Most fuel gauge circuits have a buffer to prevent gauge fluctuations while driving. That along with baffles and a sump in the tank give smooth gauge movement. I'm guessing the Seneca is not that sophisticated.

[Mr.Oz]

1500 miles this season so far. Went until the gauge showed 1/8 tank after filling passenger first. 50 gallons filled it up. Pretty close

[Watt]

Thanks Mr. Oz. What was your miles/gallon for the 50 gallons?

I took my unit in to Freightliner yesterday for some a/c work. The service writer explained fuel is pulled from the driver's tank and that both tanks are equalized thru a vacuum valve system. He was unaware of the process to fill passenger side first or what the useable fuel is in the tanks.

I'm currently at about 1/2 tank on the gauge with over 230 miles. Will fill up after I get it out of the shop and report miles per gallon.