Camano fuel line issue

[NCheaven]

Delighted with the boat, but an old issue is getting worse: On a run of over an hour of so, typically @ 7.2kts or so, the starboard fuel tank goes up while the port tank goes down. A recent 5 hour trip to Belhaven left the starboard tank @ 7/8 full, and the port tank @ 1/8 full. I refueled, putting 40 gallons in the port tank, and 20 in the starboard tank. I've adjusted the return line valve on starboard to only 1/2 open on recent runs, and that is not enough to change the outcome, so I plan to more fully close the return valve on starboard further.

FYI in 2017 I had both tanks' fuel polished, and 3 polishing cycles run until the polishing filter was clean. I have cut open a Racor filter after a season to see if there was any debris picked up in this 10 micron primary filter - found nothing at all visible after rolling the entire 25 or so foot filter element out in my driveway.

So, Camano folks - others welcome, of course, what is the likely problem:
1. Debris around the starboard tank fuel pick up that keeps it from feeding the engine at the same rate as port?
2. Debris in the port tank return line that forces all the return fuel to starboard?
3. Balancing line, if there is one, between the two tanks blocked?

Looking at having a mechanic diagnose and repair the problem, unless I come up with a simpler fix, with your help!

NCheaven

 

[Greg S]

Otter had the port tank level rising. I kept closing the return valve for that tank until it evened out. Once you find the correct setting for the valve you don’t have to change it again. It took a long time to get it right.
A valve half shut compared to fully open is barely a noticeable difference with the comparatively low flow of the return.
One line returns more than the other, I believe, simply because they aren’t balanced flow rates. A bit more restriction in one line, from any cause, will significantly effect the flow.

 

[NCheaven]

Good point, Greg. 1 to 2 gallons an hour is a minor drip. Thanks!

NCheaven

 

[nussbda]

Make sure the fuel tank vents are clear as well.

Dave

 

[DrissZougari]

I had a similar issue few years ago that was resolved by clearing the vents!
Having the return completely closed to one tank could cause the other tank to overfill.
Driss,

 

[Jeff F]

If you have valves on return lines, you'll also likely have valves on the feed lines. Check to make sure they're both open. Your symptoms could be draw related rather than return related. This usually also acts as a crossover. If both valves are open the tank level should equalize.

 

[C lectric]

Often time a failure to equalize is due to an imbalance in the load the boat carries. Often the start is at the factory and how they load/install the equipment into the boat.

Then we make it worse by not paying attention to how the gear weight is added.

Move heavy tools and supplies to the other side to try to balance the boat better.
That likely won't eliminate it but will help.

If you have trim tabs use them to reduce the list which will also help with the fuel balance.

This is one place where I continue to use my gate valves as they can be adjusted in small amounts. Just be sire the shaft seal is tight. Better of course would be a good Globe valve.

I finally resorted to some lead ingots and that also helped.

I too have gone through this with my different boat and I still have a list but it is now down to a difference I can live with.

Pay attention to the suggestions of the others , hose kinks, vent hose plugs, more elbows on one line than the other.

 

[fgarriso]

I know this is probably dumb, but why don't you return to the tank your drawing from?

 

[rwidman]

I own a Camano and cruise extensively. All the fuel valves are normally left fully open and the boat sits level when empty at rest. I don't have the problem you are having.

I have notice a slight unevenness of fuel use when two people sit on the flybridge while running for several hours because there are three seats so there is always more weight on the side that's occupied. I remedy that by moving the other person to the other side for a while.

You could have a partial blockage in a tank or fuel line. Or one valve not fully open. A blocked fuel vent could cause this problem but you would also have difficulty filling the tank if the vent was blocked. It's easy to check though.

 

[rwidman]

I know this is probably dumb, but why don't you return to the tank your drawing from?

The Camano has a tank on either side of the boat and it's designed to draw fuel from both tanks equally. If you just use one tank, the boat will begin to list.

 

[Jeff F]

The Camano has a tank on either side of the boat and it's designed to draw fuel from both tanks equally. If you just use one tank, the boat will begin to list.

I maintain complete control over list when drawing and returning from a single side tank by switching between tanks as fuel is consumed. There are advantages and disadvantages to both approaches.

The valves are there for a reason.

 

[fgarriso]

If you were to return to the tank your drawing from you could simply run for a few hours or until you notice a list. Then switch sides and returns.

I have five tanks and that is the way we do it. I also have a fuel polishing system that will pump faster than we burn. So the polishing system can be used as fuel transfer when needed.

Or you could install a 1" crossover between each tank with 90 deg shutoffs for safety.

 

[Jeff F]

I think the OP should switch the draw and return to the full(er) tank. Operate that way for a while. Any serious blockage in draw, return or vent on that side will become apparent. The motor won't work if any of them are completely blocked.

Assuming no issues, when the boat starts listing away from the tank you're using switch draw and return to the other side. Be alert for symptoms of blockages.

This will give assurance that both sides are OK, or narrow the search for the problem.

I don't mean to argue over how you guys operate your boats, but it's worth recognizing that you do have a choice in the way you draw down the tanks. There's lots to be said for keeping the two independent.

 

[Barrie]

I have the same problem and agree with Greg S. The slightest adjustment on the return valve all of a sudden fuel tank level switches to the other tank and grows. I have come to the conclusion that the engine returns way more fuel back to the tank than what it burns. Fine tuning is an understatement.
Barrie

 

[capefearcruiser]

Camano fuel burn

I had this problem with my Camano "fixed it" by adjusting the water levels in the tanks. I have a level gauge below the windshield (center). When i list to one side, i cut the opposite water tank off until it levels off. Works for me.

 

[rgano]

If you suspect a vent or supply line clogging issue, you could draw and return fuel to the one tank at a time at a high speed watching the Racor vacuum gauge. This practice might cure an insipient supply line clog.

 

[NCheaven]

Great suggestions from everyone! Thank you! Waiting for April to de-winterize the boat and apply what y'all (surely you expect "y'all" from NC guy) have suggested....

NCheaven

 

[Wolfgang]

Here is another item to check. If your fuel lines between the tank intakes and the fuel pump are made of rubber hose, the hose can collapse with aging and restrict flow.

 

[YellowPiper]

I to have the same issue. Was not a concern when i was a weekend warrior but am now doing the loop.
Stb tank always fills up when both returns open
Problem improves when stb return closed but does not go away.
I have yet to see fuel come out of over flow on stb side. Over flow works
Also almost ran port tank dry one run when both started at half. Buy end of day. Stb almost full and port empty.

Issue only occurs when pushing the boat. Like 8.5 knots or 2400 of 3400 rpm on my Yanmar 200 hp

Colin
Detour
Camano 31
Hull 248
Somewhere in florida doing the loop

 

[NCheaven]

Here's the outcome: Starboard Return was a normal flow. Port Return did not flow until starboard return valve was almost completely shut, then the Port return valve flow was high pressure and narrow, clearly a clog, most likely in the fitting where the engine return flow is channeled to Starboard and Port return valves, the ball valve or valve tip. Initial mechanic recommended simply closing the starboard return, letting the port return feed the port tank, with the tanks balancing through the common connecting hose. I felt that such might burst a hose, create too much back pressure on the fuel pump or cause a bigger problem than the one we started with. So, I ran at moderate rpm and the starboard return 3/4 closed on the way to a boat yard, with the agreement that they would pull the fitting where the engine return splits into port and starboard. The tanks stayed relatively balanced underway.

The yard pulled the fitting, gave it and the return valves a Varsol bath, and the tech used a compressor to blow out the return hoses, etc. I also had the fuel polished while rocking the boat as much as possible. The polishing primary filter, 10 microns, gathered a small amount of what looked like calcium carbonate in sand sized granules and a little green stuff in the filter element, after running what the yard estimate was 3x the fuel in the tank. The tech and I both thought that the polishing succeeded in showing that the fuel tanks weren't perfect but were very clean since the last polish 6 years ago.

The tech also evaluated the two Racor bowls, and agreed they looked very clean with no water.

Running back to home port the filters stayed pretty balanced apart from the battery induced slight list. I refueled locally, list has the tanks 3/4 P and full S after 30 minutes at the dock. Next run I will draw from the starboard tank and return to the starboard and a bit to the port tank, knowing that starboard tank will drop under way, rebalance slowly to slightly more in the starboard tank when docked due to battery induced starboard list.

So, there was a clog of some origin in the port return, probably in the fixture that splits the engine fuel return into separate tank returns or port return ball valve or valve tip, and the imbalance in return pressure is now pretty much the same.

The yard tech and I wisely did not want to cut off the starboard tank completely due to the risk of blowing a fuel line or harming the fuel pump.

Not easy or cheap addressing the problem, but we avoided creating a bigger, more expensive problem.

Fueled up, ready to go on the next cruise!

Thanks TF Camano owners and other TF experts for your encouragement in this matter!

Alex

 

[Barrie]

Thanks Alex, I learned a lot from your experience.
Barrie: Thanx:

 

[NCheaven]

By the way, mechanic did check the vents, found minor spider debris, cleared it. The open line between the two tanks takes about 20 minutes after shutting down the engine to balance the tanks when one is far more full than the other....seems slow, but works. I look forward to finding the balance point in return valves now that the port return fitting and valve have been cleared. Initially it looks light slightly more than half closed on the starboard return - big improvement from 7/8 before fitting/valve cleaning. Of course, having 4 house batteries on starboard makes the boat list a little to starboard at rest and underway.

Thanks again, TF Camano folks and others!

Alex

 

[rwidman]

By the way, mechanic did check the vents, found minor spider debris, cleared it. The open line between the two tanks takes about 20 minutes after shutting down the engine to balance the tanks when one is far more full than the other....seems slow, but works. I look forward to finding the balance point in return valves now that the port return fitting and valve have been cleared. Initially it looks light slightly more than half closed on the starboard return - big improvement from 7/8 before fitting/valve cleaning. Of course, having 4 house batteries on starboard makes the boat list a little to starboard at rest and underway.

Thanks again, TF Camano folks and others!

Alex

I would try moving things around in the boat to eliminate that list at rest. For example, I have a spare prop stored in the lazarette that is stored on the side that helps to eliminate a list.

Also, with two people riding on the flybridge, one will be on one side. You can move that person to the other side for half the trip.

 

[NCheaven]

Camano weight distribution

Good advice, thanks. A part of the problem is that we have 4 house batteries plus usually my weight to starboard, and only the starter battery and my much lighter "Admiral" in her chair (modification by shortening the table) to port. We have distributed most of the other items 10 lb. each or more per your plan. Flying bridge periods (which we enjoy so much!) and seating are mostly determined seas, by sun position next, weight distribution after that. The fuel load enhancement will help us a great deal now that the return fitting has been cleaned out, and if on a long tack, we can adjust the fuel returns/draw accordingly.

Fall cruising ahead - great time to enjoy our Camano's!

Alex