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2010 Seneca HD fuel tank question

Yahoo Message Number: 16713
Hey everyone. I have a question about my 2010 Jayco Seneca HD 35GS on a C5500 Kodiak chassis with the Duramax. I've owned it for about a year now and have a question about the fuel tank. At 1/8 tank on the gauge it takes about 60 gallons to fill it up. Specs show 80 gallon tank so off but not too far off if that's the case. While under the truck today saw the decal on the tank and it says it's a 109 gallon tank. So the gauge would be way off at that point. Anyone know how to figure fuel tank size off measurements? Also, I'm assuming I'd have to drop the tank to get to the sending unit, does it run a factory GM sending unit or an aftermarket?

Thanks for any info.

Re: 2010 Seneca HD fuel tank question

Reply #1 –
Yahoo Message Number: 16714
I have a 05 35GS Duramax, my take was listed as 80 gallon also. The one time I let mine get to about 1/8 tank it took nearly 70 gallons to fill it. My gage is pretty constant... requiring 20 gals at ¾, 40 at ½, and 60 at ¼.

Billy

Re: 2010 Seneca HD fuel tank question

Reply #2 –
Yahoo Message Number: 16715
I have a 2007 Seneca ZX. It has an 80 gallon tank but I have never put over 60 gallons in it when filling up (fuel gauge at 1/8). I suspect that GM calibrated the gauge this way to help insure that owners would not carelessly run out of fuel and need to go through the whole priming procedure to get back up and running. It is more problematic running a diesel out of fuel compared to a gasoline engine.

Frank

Re: 2010 Seneca HD fuel tank question

Reply #3 –
Yahoo Message Number: 16716
Nice problem to have! Not sure it's worth digging in to, to far. If you are consistent putting 60 gallons in at 1/8 tank, that is a heck of a reserve. I'm usually looking for fuel at 1/2 a tank on 70 plus gallon M2 saddle tanks.

Enjoy the ride?

Smooth Sailing,
Ric Golding
Carlyle, Illinois



Re: 2010 Seneca HD fuel tank question

Reply #4 –
Yahoo Message Number: 16717
109 gallons is what my tag said. At least 10% of that is allowed for expansion. Some is for length of pickup above bottom of tank.
If you want to have gauge read better at a center level. Remove the gauge cluster. Then reposition needle to be at 1/4 when you normally need 60 gallons. You need to pull needle straight off. Then reposition it to the amount you want needle moved when reading 1/4 tank. Do this with ignition key removed. Engine off.
For reference, when my tank was full with fuel showing in filler tube. It took 100 miles for fuel gauge to start moving. It's a GM thing. This is assuming you are not climbing mountains. Then all the 1/4 readings showed correct for amount of fuel needed. Most fuel I ever put in tank was 74 gallons. Always started looking to refuel at 1/2 tank.

Best
Ron Hall


Re: 2010 Seneca HD fuel tank question

Reply #5 –
Yahoo Message Number: 16718
Thanks for the input. We do a lot of boondocking so that is the main reason I wanted to dig into it. Knowing actual fuel amounts could be the difference between heading into town middle of a trip just for some fuel or waiting until we are heading back out on the road to fill up. We are leaving out Tuesday from Georgia to Oklahoma, I think I'm going to run it until the fuel light comes on and see what it takes at that point.


Re: 2010 Seneca HD fuel tank question

Reply #6 –
Yahoo Message Number: 16719
I have an 05 endurance. When the gauge was just below E, it only took 72 gallons in an 80 gallon tank.


Re: 2010 Seneca HD fuel tank question

Reply #7 –
Yahoo Message Number: 16720
I have an 05 Endura and I have run it down to the red on the gauge a couple times and never put more than 68-70 gallons in. If you haven't done it recently I recommend draining to water out of the tank. The drain at bottom is a 3/8 ratchet, don't take the plug out just loosen til only a couple threads left, last time I did it, I drained probably two gallons of water out of it. All the temperature swings and differences in humidity these things are subject to, they condense a lot a water in a short period of time.


Re: 2010 Seneca HD fuel tank question

Reply #8 –
Yahoo Message Number: 16722
My 2007 kodiak diesel MH
              Gas tank labeled 81 gals
              Could only get 60 gals in tank
              I dropped fuel tank and raised copper vent inside of tank approx.. 3 inches
              I dropped generator pickup tube (copper) to 1 ½ inches off bottom of tank
              Fuel pick up assembly with float had four settings to adjust float to ( I raised adjustment up one notch )
I was now able to put 78 gals in tank and increased my driving distance, plus gen ran longer without running out of fuel

Re: 2010 Seneca HD fuel tank question

Reply #9 –
Yahoo Message Number: 16723
I owned a boat for many years and once we paid to "polish" the fuel tanks. That is, pump out the diesel, run through a filter and drain all the moisture out of the (nonvented) 600 gallon tanks. I asked (not here) whether I needed to do this with our Seneca 34SS. Seems like a rather different process but still an issue to address.


Re: 2010 Seneca HD fuel tank question

Reply #10 –
Yahoo Message Number: 16724
Running until the light comes on sounds like a plan. I'd be quite nervous as the where I was while doing this and might even carry an extra 5 gallons.

Smooth Sailing, Ric Golding Carlyle, Illinois



Re: 2010 Seneca HD fuel tank question

Reply #11 –
Yahoo Message Number: 16725
I would be carrying 10 gallons of fuel and a spare fuel filter.

--
Best
Ron Hall

Re: 2010 Seneca HD fuel tank question

Reply #12 –
Yahoo Message Number: 16726
I always keep a spare fuel filter with me. I also manage one of the largest road side service fleets for class 8 trucks in the country so if I'm on a highway I'm generally covered I'm going to give it a shot and see what happens. I've never even had the generator cut off on me so I'm going to go till it shuts down and then fuel up.


Re: 2010 Seneca HD fuel tank question

Reply #13 –
Yahoo Message Number: 16727
Eric,

Interesting experiment and it sounds like you have the expertise and backing to handle any situation with your experiment. I have always been shy of letting the generator run dry for concern of letting it pull air into the fuel line through the vents and cause a need to re-bleed. Not that I can't do it, just didn't want to. Look forward to hearing about your experiment and results. I've always wondered what triggers the shutoff of the generator and hope it is a sensor and simple shutoff and not a starving of fuel.

Smooth Sailing, Ric Golding Carlyle, Illinois



Re: 2010 Seneca HD fuel tank question

Reply #14 –
Yahoo Message Number: 16728
I have had the experience of the generator shutting down due to lack of fuel. A couple of years ago, while on a trip, the gen would run normally for a few minutes then struggle to remain running then sometimes either die or run normally. I have a short section of clear return fuel line and observed there was very little and sometimes no fuel flowing back to the tank. I had a spare in line diesel fuel pump and spliced into the fuel line. With the addition on this pump, the gen ran as normal. It did not require anything pressing the button and priming the engine until a good sized stream of diesel began flowing thru the return line. When I arrived home, I removed the fuel filter, which had been replaced only days before the trip, and fuel pump. I removed the fuel supply and return lines and routed them outside the gen box where I installed an inline fuel filter and an inline fuel pump both of which can be replaced in minutes. All that was required to get the gen to start was once again hold the prime button until the return fuel line was full of fuel. Then just press the start button and it fired up and has done so ever since.
It is my understanding the only sensors are for low oil and high temp but don't know how either is determined since the only way one is aware is when the gen shuts down. In order to help me understand how the gen is operating, I installed an oil pressure gauge and a temp gauge. As soon as the gen starts, these gauges begin showing the results and are helpful in knowing the oil pressure and coolant temp.
Hope this helps
Don

Re: 2010 Seneca HD fuel tank question

Reply #15 –
Yahoo Message Number: 16729
So the generator cuts off about 20 miles after the fuel gauge hits empty. At that point stopped for fuel about 5-10 miles further down the toad and it took 76 gallons. "Thumping" on the tank it seemed to still have a decent amount in it but at least now I know. Generator took about 30 seconds to prime, sputtered for a minute or so and has been fine since.