MCI aux fuel tank

quantum500 · April 26, 2009, 08:27:39 PM

I have an 8. How does the factory aux fuel tank fill?

Tenor · April 26, 2009, 08:51:27 PM

There are 2 lines that run under the bus from the main tank to the aux tank. They should be under a shroud. There is also a balancing line that runs from the top of the main tank, along the side of the tunnel, and into the top of the aux tank. That allows air to be displaced as the aux tank fills from the bottom. Hope that helps!

Glenn

quantum500 · April 26, 2009, 09:28:20 PM

Thanks Glenn. I knew it was simple.

Singing Land Cruiser · April 27, 2009, 08:42:45 AM

So, when you fill your tank, it auto fills the aux fuel tank and the fuel use rate is the same in both tanks? M&C

buswarrior · April 27, 2009, 08:58:26 AM

The tanks are interconnected top and bottom. Gravity just lets the fuel flow where it wants to go.

Don't go into a town in a steep valley with the tank down near a 1/4....

The fuel runs to the back, into the aux, and away from the fuel pick-up in the main tank.

Picturesque little place in La Belle Province has 12 % slope out of town. Back in the day, charter company forbid buying the higher taxed fuel in said province...wait until you cross back into Ontario. So, fuel at the line on the way in, and run the tank almost empty to get out....Sounds good, and many transport outfits did the same thing back before IFTA... It took three different trips, three different out of fuel rescues, with the same coach, to finally discover the driver needed to put $25 of fuel in it, in that town, to make the slope out. And everything was fine from then on.

Serious business when a driver is fired for running out of fuel...all was forgiven...eventually.

Now, keep it in perspective, the fuel wouldn't have been very deep in the regular tank without an aux under this condition. I like a big fuel supply. Aux tanks are great for lengthening the stride of your coach, and give you more choices for where to purchase fuel and how long to boondock on the generator.

However, same as any coach, there are implications if you go mountain goating!

happy coaching!
buswarrior

happycamperbrat · April 27, 2009, 09:20:41 AM

I can personally testify to this fact. I purposely ran low on fuel on a recent trip to burn up some old diesel and planned on getting diesel in Gilroy California. Well, unknown to me being a newbie in an unfamiliar area, I went down a really really steep hill and at the bottom ran out of fuel! I had to call a tow truck driver, and wasnt sure exactly where I was or what the last exit sign said, I told the tow truck driver I needed GAS LOL!! I was parked for about 8 hours with flashers going (hurah for new batteries, I didnt need a jump) and went thru 2 highway patrol officers and 3 different tow truck companies before I got rescued. Oh and it takes 15 gallons to prime, NOT 5

BUT I had just a little under 1/4 tank when I ran out of it in my fuel lines! My bus in an RTS, so I think this may apply to any bus.

Singing Land Cruiser · April 27, 2009, 10:20:27 AM

So then 1/4 tank should be the least amount one shoulh carry in a coach with an aux fuel tank when going into a hilly area? And does the make, year and model matter? M&C

johns4104s · April 27, 2009, 10:28:31 AM

Do most 8 and 9,s have the Aux tank? Were is it mounted? Does it have its own filler cap?

Thanks

John

JackConrad · April 27, 2009, 10:32:35 AM

Quote from: Singing Land Cruiser on April 27, 2009, 10:20:27 AM
So then 1/4 tank should be the least amount one should carry in a coach with an aux fuel tank when going into a hilly area? And does the make, year and model matter? M&C

I think all MCIs are similar, although all do not have the aux. tank. We NEVER let our tank get below 1/4. And, when we add fuel, we fill it full. This helps prevent condensation forming in the tank and contaminating the fuel.
If it has an aux. tank it is behind a panel in the center of the front baggage compartment and located against the rear bulkhead of this compartment. Floor to ceiling, approx 2' x 2'. It is inter connected to the main tank underneath the baggage bay floor and an interconnecting vent at the top. It fills when you fill the main tank and feeds the engine at the same time as the main tank. No valves or separate fill. Jack

bcaddel · April 27, 2009, 11:15:07 AM

I think our MCI 7 says including the aux tank it holds 179 gallons (or there about). What is the most fuel anyone has put into an MCI with a aux tank during refueling.

We are about to embark on our 7,500 mile excursion across the country this Friday and just curious about how many actual gallons MCI owners have taken their tanks down to. I usually go down to 1/4 on the fuel gauge but it has never taken 100 gallons to fill it back up. I understand most of the gauges aren't that accurate so I am wary of going much below the 1/4 mark but may be tempted to on this trip just to save some time by eliminating a fueling stop or two.

Bob

Singing Land Cruiser · April 27, 2009, 11:20:32 AM

Our MCI 102a3 has the aux fuel tank and holds a total of 191 gals. M&C

John316 · April 27, 2009, 12:26:01 PM

Our tank capacity, with auxiliary tank, holds 227 gallons. We almost never run out tank down below a quarter tank. We do take advantage of the bigger tanks. Especially when there was the fuel shortage down south earlier this year. We filled up whenever we could, and never had a problem.

I think that the sticker says not to put more than 220 gallons in the tank...how do I figure that out

I just fill it up until I can see the fuel

.

God bless,

John

gumpy · April 27, 2009, 12:41:21 PM

I have the aux tank in my MC9. I think the most I've ever put in is about 139 gallons last month in WY. Was starting to get a bit worried. Would have to look through my records. there was a time shortly after I bought the coach that I went almost exactly 1000 miles on a tank of fuel. I made the mistake of relying on a gauge that was not functioning properly.
I got to my destination thinking I still had 1/8 of a tank of fuel. Unfortunately, I parked on a slight left banking slope and all the fuel ran to the driver's side of the tank. When I started it to
go get more, it ran for about 3 minutes. Took me a full day of learning how to reprime it. Fortunately, I had the help of a very famous busnut from the board who just happened to live literally across the road from where we were staying. He shuttled me to town for about 20 gallons and an electric pump to get it going again.

Changed the gauge. Haven't run out of fuel since, but I have do from time to time have issues when it gets down around 1/8 when I go around a right hand corner, such as an interstate on ramp or cloverleaf. Again, all the fuel runs to the left, and I suck air into the intake. About a half mile down the road, the engine starts loosing power and I have to jump out and go switch on the permanently plumbed electric priming pump. Happened more than once. I'm a slow learner.

craig

Hi yo silver · April 27, 2009, 08:54:45 PM

Hmmm,
Now I'm wondering why Custom Coach installed a fuel transfer pump on my conversion.??
Dennis

JackConrad · April 28, 2009, 04:38:05 AM

Quote from: Hi yo silver on April 27, 2009, 08:54:45 PM
Hmmm,
Now I'm wondering why Custom Coach installed a fuel transfer pump on my conversion.??
Dennis

Dennis,
Do you have a separate fuel tank for your generator, Webasto? We are going to install a transfer switch to pump fuel from our main tank to our generator/ProHeat tank, should the need arise. Are you sure the pump is to transfer and not to to prime? Jack