How do I find out what the fuel/gas capacity is?

How can I tell how many gallons our gas tank is? We just bought a used Class C gas RV. It's a '93 Gulf Stream Conquest Limited Edition on a Ford '92 E-350 chassis. Our friends that we bought it from said there are 2 gas tanks (and that she thought it was 100 gallons) but just 1 place to fill the tanks (not 2). She said that you fill it and it basically fills the first tank then flows into the 2nd tank (which takes a while) and then you can fill it up with more gas to top off that first tank (the one that had since drained into the 2nd one.) Someone on this forum said it is doubtful that it has 2 tanks otherwise it would either have 2 places to fill the tank or 2 fuel gages on the dash.

On our trip home this past weekend after buying it, it sure didn't seem like we were filling up a 100 gallon tank. The motor home manual doesn't say anything about number of tanks or fuel capacity. The Ford Econoline manual that came with it says 36 gallons. I'm not sure if that would be different since it is a motor home and not just a Ford van??

36 gallons just doesn't seem like a lot to me, although when we had a little less than a quarter of a tank left my husband filled it about 30 gallons. So perhaps 36 gallons is the correct amount. (Was really hoping it was more than that though as the gas mileage would still make us stop for gas as often as we would if driving our Camry. 36 gallons, 10 miles to the gallon, 360 mile capacity....which is the same miles my Camry can go.

One thing you could do is crawl underneath your RV and see how many gas tanks are there.

Best advice is to do like Arch said and look and see how many tanks there are and about how big.
I have never heard of a gas coach having two tanks and one filler.
Bill

Length X width X depth of the tank in inches divided by 231 will give the tank's capacity in gallons.  There are 231 cubic inches in a gallon.

Thanks everyone!! I'll take a look then! And do some measuring. Thanks!!

Let us know what you find!

So I'm not sure which one is the fuel tank. Or if both are??

This photo says not to torch or weld so that may be a sign that it is the fuel tank.

I'll post the next photo in the next post.

And here is the one next to it (behind it) which seems to be connected to the one I already posted maybe.

Are they both fuel tanks?? Or just one?

Ok what does the white sticker say? I am just guessing but it looks like an add on tank from Trans Flow. I can't believe they would install it without an way to fill it. letting the fuel flow between them when filling would take a long time. Look again for another gas fill it may be hid in a compartment. I also can't believe they would not have a valve to control/separate them if you wanted to.
Bill

Also that rubber line looks awfully close to the ground. Unless the grass needs mowing in that area.

Rene T said:

Also that rubber line looks awfully close to the ground. Unless the grass needs mowing in that area.

Click to expand...

Well atleast the hose isn't hanging below the tank. The other troubling thing is the Trans Flow tank is higher than the original tank. Without seeing it it looks like it might be a problem, if you fill the TF tank with no shut off and the fill is lower on the main tank it could overflow.
Bill

I think it being low to the ground and close to grass is just the perspective of the photo. Here's a photo of fee clearance.

Here's a zoomed in photo of the sticker.

I can't quite make it out but it looks like a 63 gal tank.
See if you can find the filler tube. I still think there should be a valve to separate the tanks.
Bill

here is their web site.
https://www.transferflow.com/
Bill

My husband and I have both been looking at their website. We'll have to go do some investigating for another fill tube.

What do you mean a value to separate the tanks??

And yes, it does look like it says 63 gallons. So in theory the original tank should be 36 gallons according to my Ford Econoline manual. And apparently the add on tank is 63 gallons.

On our trip bringing it home the most my husband filled it was 41 gallons. Our fuel gage said it had just a bit less than a quarter of a tank when we stopped and filled it 41 gallons.

Also....with an add on tank...does that mean we never REALLY know how much gas we have left?? 

It definitely wouldn't make sense for the gas to flow from the original take UP into the add on tank. That would make the add on tank pretty impossible to actually fill? I think? In theory, IF we were able to completely fill the add on tank and then it flowed into the original tank as gas in the original tank is used, then while driving our fuel gage should stay on FULL for a while....until the add on tank has finally run out and the original tank finally actually starts depleting. BUT....that didn't happen. It never stayed on FULL for an abnormally long time. We did fill it 41 gallons when while it still showed we had almost a quarter of a tank left. So that's something since the original tank, according to the Ford manual, is only 36 gallons supposedly.

You said you bought this from friends. Have you considered asking them how they used it to take advantage of the second tank?

Hmmmm.... have you looked around in the storage (both sides), areas near the add-on tank.. for another fuel cap ??

We will have to look in daylight tomorrow for another cap. Our friends only had it for about a year. They bought it basically for one big family trip. She did say she thought it was 100 gallons (which 36 + 63 would be 99) but she said that the one fills into the other. So basically you could get gas, then stop for dinner, then fill again and while you are at dinner it fills into the 2nd one. So that's all she knew. Or just seems like you could never really fill that 63 gallon tank. Her husband wasn't there when we picked it up. He was called away for work out of town so we didn't get to talk to him except through her. He's pretty handy though and did work on it for their trip so it seems like he would know if he found a second fill tube. He must not know of one....IF there is one.