CB 35 Fuel Tankage

[Maogwaicat]

Hello Groovy Guys and Gals,
Gotta big question about fuel tanks. I try to keep diesel tanks full as a matter of preference and to keep water and other gooey stuff away from our motor. Here is my question;
I read and hear that the CB 35 has two tanks with a total of 260 gallons, which I presume is 130 gallons per tank. I have run the fuel down to almost empty a couple times but the total fuel I have placed into both tanks is 160 gallons , total. Are my fuel level indicators erroneous? My guestimate is that I'm reading next to zero yet have ninety gallons somehow still in the tanks. Anyone else see this issue?

My next task is to figure out how to get a dipstick into the tanks. Or is it that I only carry One Hundred Sixty Gallons of diesel? I hope not...
Thanks for any advice!
DC

[Nancy]

We haven't owned Valentine long enough to know for ourselves, but the previous owner said the gauge is wildly off. Here's his info:

o When gauge reads 3/4 full, it takes 40 gal to fill the tanks.
o When gauge reads 1/2 full, it takes 75 gal to fill the tanks.
o When gauge reads 1/4 full, it takes 100 gal to fill the tanks.

He once had a scary unplanned situation in the Bahamas where he ran for 1.5 hrs with the gauge reading empty. Turned out it still had 70 gallons in it.

We believe the total capacity if 260 gal. If you figure out how to stick the tanks or even where the sending units are, we'd sure like to know!

[Maogwaicat]

Quote;
o When gauge reads 3/4 full, it takes 40 gal to fill the tanks.
o When gauge reads 1/2 full, it takes 75 gal to fill the tanks.
o When gauge reads 1/4 full, it takes 100 gal to fill the tanks.
End Quote

Thank you Nancy, that is about precisely what I have been measuring, having used about 700 gallons (per the Flowmeter). At a smidgen above Empty, I placed 160 gallons twice into the tanks.

I will dip tanks, might have to buy flexible dipsticks but I will learn more. There sure are a bunch of mysteries concerning these CB35's.

Off topic, I would be interested to hear what caused the failure of your Yanmar motor sometime, just so I might learn to avoid the same experience.

Thanks for the assist!

DC

[Rondo]

After a recent trip, the fuel gauge on our 2007 CB35 with Cummins380 QSB showed a pinch above 1/4 remaining. We keep careful track of hours run between fuel purchases, and used the average of 7.5 GPH to make a S.W.A.G. as to how much fuel we used. For anyone who might not know, SWAG is 'Scientific Wild A** Guess." It has proven to be quite reliable.

From the hours, I calculated that we needed about 140 gallons to fill up. Our home fuel delivery guy was in the neighborhood with a partial left in his truck and called to see if we needed some. We took 100 gallons, and afterwards, the fuel gauge showed a level I recognized from past experience. I guessed another 40 gallons would have filled the tanks, taking the total right to the 140 I calculated. Which means, with the gauge showing 1/4 plus, we had about 120 gallons remaining. I suspect that the tanks are NOT rectangular and square, but are likely tapered both from front to back, as well as tapered from top to bottom. Since the float sender can only tell you the level , the varying shape of the tank cannot accurately show the remaining level in gallons It would need an algorithm in a small controller to be more accurate. Experience is the best guide in this case.
As always, your mileage may vary.
Ron O

[Maogwaicat]

Ok, we made a couple trips Northward and back, I now needed to find fuel. I have two photos of the gauges and we were at zero for both. We took on 173 gallons of diesel so the usable fuel remaining at ZERO was about 87 gallons. Good to know but I am nervous to presume amounts unless I am able to time when zero occurred. I would also presume that the 87 gallons left might really mean 80 gallons or so, really available to power the engine. I would not want to bet my safety on that...
https://www.albinowners.net/aog/downloa ... w&id=28676

[Nancy]

Darryl/Mogwai -- your experience with the gauges reading empty pretty much matches what the PO of our boat told us. One time in the Bahamas, through a miscalculation/misjudgment, they ran very low on fuel and ended up running for 1.5 hrs with the gauge on empty. When they got to a fuel dock, the tanks still had 70 gallons.

But I agree with you -- this is much too close for comfort even if 80 gallons is enough to run 8-10 hrs.