Fuel capacity of E34 (1987)

[CaptnNero]

Is it really full ?

In another thread I described how our tank was plumbed, with the vent and fill hoses drooping well below the top tank level and full of fuel. My tank is airlocked. For fuel to enter via the filler hose, air in the tank has to bubble thru the vent hose loop intead of just having the air flow out the vent tube. With the engine running the lift pump is strong enough to suck some air into the tank through the same vent hose so the fuel keeps flowing to the engine. Plus most of the fuel comes back to the tank via the return line anyway.

What I'm getting at is if yours is the same way, it may not actually be full when you think it is. When I fill the tank, it can overflow and only be half full. To check you can slowly remove one of the fuel gauge screws on the tank top immediately after it's been filled. First, there shouldn't be any air hissing in or out. That was the tip in my case. Then you can dip one of those long wooden skewers in the screw hole and see just how high the fuel level is. You might be surprised.

Unfortunately, I tested our 1989 E34 the hard way by running out of fuel. Attempts to bleed and prime by filling the fuel filter at the dock on the level were not successful, supporting the totally empty of usable fuel theory. Refilling completely to overflow (whoops - I thought it held 30 gallons!) took 22 Gal.

 

[EGregerson]

Penalty?

Is there a prohibition against waking a long sleeping thread? My apologies if that is the case. I had occasion to "polish" my fuel; I noticed on the Racor tank (installed in my '87 E34) a foil label on which was scribed, in addition to some other information, "27 gal."

 

[Loren Beach]

the Archives are open...

Any "unlocked" thread (and 99% are) can be added onto. Wander around the archives... lots and lots of interesting information lurks there...

Once you get used to invoking the "Search" command in the blue color bar at the top of this it becomes almost addictive!

This is a wonderful and well informed group of sailors. Patient with each other and ready to help out another owner.

Enjoy!

Loren

ps: if you find the Ark of the Covenant, please let us know...

 

[sailingdeacon]

Regarding any label you may see, be sure to read the earlier posts here which showed the computed capacity using the actual demensions of the tank. The capacity was reduced however with other considerations described in detail. So the net is that it is around 22 gallons.

 

[CaptnNero]

When is it full ?

This is interesting. On the one hand there is the physical capacity as computed from the drawings. On the other it depends on your filling procedure. While one may intend to fill to just below the hose cutout level, how do you really tell ? Because of the tank shape, the greatest capacity is at the top of the tank, so how much of that you use will greatly determine your own "full" capacity. When filling my Pearson with a fast nozzle, I would stop filling when fuel would start to foam out of the vent.

As I stated previously in another thread I discovered an airlock problem on my two Ericsons which on the E34 caused the tank filler tube to overflow at about 15 gallons in certain conditions which I will not detail here.

Since I will be emptying the tank over the winter, I will do some careful measurements next spring and inspect the level with the fuel sending port open. The results will be reported to this thread.

 

[sailingdeacon]

Keep us posted....

I will add this: I replaced the tank guage unit. I carefully installed it as per instructions, so the "up" arm was properly positioned with fuel at that level. As in the past the metrer guage itself showed full up. But based on use I do not think I get more that 22 gallons or so. To me it implies that perhaps it is not an airlock issue, but instead when the guage in the tank goes as low as it can, there may be lots more fuel there. The tank is very oddy shaped, with the guage arm hopefully pointed toward the centerline where the deepest part of the tank is. If it is not pointing there, clearly it will not measure the lowest part of the tank.

 

[CaptnNero]

bottom tank taper, diminishing returns

In my case I knew it overflowed at 15 gallons because I had to pump it empty to polish the fuel, so the exact amount of fuel was measurable. I was quite surprised at that finding.

You make a good point about the gauge arm swing. The hole pattern on my sender only allows it to be installed one way. I think it's five screws with some asymmetrical spacing. Since the bottom of the tank is very tapered for the bilge I wouldn't expect there being much towards the low end of an empty gauge reading unless the arm swing is way off but you could be right.

When I do the capacity test I'll note the gauge readings in increments. I think maybe Loren had suggested somewhere to mark up the gauge in one gallon increments. I could post that result also. I'll gladly do that much for the sailors in this forum who have been so helpful to KOKOMO and crew.

The sender is towards the fore/aft center of the tank so boat pitch trim shouldn't matter much.

... To me it implies that perhaps it is not an airlock issue, but instead when the guage in the tank goes as low as it can, there may be lots more fuel there. The tank is very oddy shaped, with the guage arm hopefully pointed toward the centerline where the deepest part of the tank is. If it is not pointing there, clearly it will not measure the lowest part of the tank.

 

[supersailor]

Loren sent me the link to this thread in case I had not seen it. I had not. I sent him back a reply on it and he suggested I reply to the thread. When the master speaks we act so here goes.

You might consider this an attempt to further muddy the waters. I am amazed at the number of different tank capacities we seem to be coming up with for the 34. There has to be more reason than a simple difference in tank sizes. I am the one with the thread for the remote fuel gauge. The 34 is a 1987, hull #15 with the fuel gauge mounted in the cut out for the filler, vent and fuel pickup. The tank is stamped 30.2 gallons. I sent the tank measurements to the engineer, Joel, at Centroid to determine the best sender for such an interesting tank. The fuel level was to be calculated by 1/8ths and he gave me a choice. Empty the tank and refill it one gallon at a time and measure the height of the fuel above the bottom or have him calculate the volumes at the required levels for $100. The thought of sloshing around in the double berth with gallon after gallon of diesel made the decision easy. I had him do the calculations from the plan in the manual with some corrections from my physical measurements. The main difference is that the drop for the fuel fill is 3" not 2 1/4".

He calculated the tank volume out at 28.69 gallons. A big part of the calculation difference is that ,I think, the cut out was not figured in to the volume causing a reduction in the volume. Plus the shape of this tank is rather extreme. Perhaps the tank manufacturer did not worry about absolute accuracy.

Right after I bought this boat, I had engine failure twice on the same day. Once in the Port Townsend Cut, a very narrow high tidal channel. A very slow sail (no wind) to Port Ludlow got me to a fuel dock. The tank topped off after only one gallon so I figured that my analysis of low fuel was incorrect. The engine started and ran well so we cast off and headed for Poulsbo. It quit once again in the Agate Passage under the bridge in 4 1/2 knots of tide. Very exciting. Luckily, we were on a Club cruise so we got a tow in to Poulsbo. The Club had a ball diagnosing this one. It turned out to be a plugged vent line. The fitting at the stern had corroded out. The point of this little story is that only a small increase of pressure causes the fuel to spill out the fill spout. When I filled up in Poulsbo, it took more than 28 gallons.


The bottom 3" of the fuel tanks holds 1 gallon. The top 3" holds 14.05 gallons. The last 8 or so gallons is in the top 1 1/2" of the tank. Any air bubbles will prevent completely filling the tank. There are several things I can think of that would cause bubbles. The most obvious is that the fill and vent lines are sagging. There is not much that can be done about the fill. It is stiff and droops low as it goes under the bunk. The vent must be taught and sloped toward the tank all the way. Mine wasn't and had to be re-routed to eliminate the sags. The second is that many of these boats list to starboard creating an air pocket in the port side of the tank. the third is that the boat is trimmed bow down causing a bubble at the back of the tank. I have noticed that several 34's bows are trimmed significantly lower than mine is. I do have a couple of hundred pounds of lead ingots glassed into the aft port side of the boat under the Quarter berth which brings the boat up to plumb and helps bring the bow up. I also have a chain/rode anchor line which is significantly lighter than the all chain system. The 34's bows are hollow which makes it slip through the water easily but won't carry a lot of weight forward. Fill the bow water tank when you have an all chain anchor line and it will be easy to see over the bow.

A linear fuel gauge will be wildly inaccurate with this kind of tank even if your gauge is mounted at the top of the tank. The capacities per inch of fill vary wildly as the tank fills. I don't know when Ericson changed to the top mounted fuel gauge which has a slightly better chance of giving readings but what is the accuracy when the bottom 3" of the tank holds 1 gallon and the top 3" holds 14.05 gallons? also a top mounted gage will not be near the low part of the tank. In my case, the gauge read full at 1/2 tank and 1/4 tank with 1 gallon left. Also it is really nice to sit at the Nav Station and be able to read the fuel level. Prior to the new gauge, I relied on a scrap of paper with the hours at fill up and the approximate hours to when I would have to start rowing tucked onto the top of the panel. To be honest, I still do that. My engine has been malicious about quitting in bad spots so I'm a little paranoid about that. I also log the fill ups but have to admit I don't look back in it, hence the scrap of paper.

I have the Engineer's calculations if anyone is interested in them. Give me your e-mail in a private message and I'll e-mail them to you. They are too bulky to post. The calculations are for the 34-2 only. That lank is unique to that boat only.

 

[Tom Metzger]

Bob - You are over thinking the fuel issue. Refuel when you get to half a tank. It doesn't matter if it is 5/8 or 3/8 of the tank... it's not important. You don't want to run out. Calculating to two decimal places is a joke. How much does the bottom flex when the tank is full? How much is in the fill hose?

If you are in a seaway the bottom quarter is lost because of rolling. If you need to use the last drop carry some jerry cans with spare fuel.

Just curious, in Washington, or any Left coast state, do the dock side diesel fuel nozzles have pressure caps to keep fumes from entering the atmosphere like some states require for car gas stations? I'm trying to understand your clogged vent line story.

 

[Loren Beach]

More Fuel-ish Thoughts

Bob - You are over thinking the fuel issue. Refuel when you get to half a tank. It doesn't matter if it is 5/8 or 3/8 of the tank... it's not important. You don't want to run out. Calculating to two decimal places is a joke. How much does the bottom flex when the tank is full? How much is in the fill hose?

If you are in a seaway the bottom quarter is lost because of rolling. If you need to use the last drop carry some jerry cans with spare fuel.

Just curious, in Washington, or any Left coast state, do the dock side diesel fuel nozzles have pressure caps to keep fumes from entering the atmosphere like some states require for car gas stations? I'm trying to understand your clogged vent line story.

Hi Tom, a couple of thoughts regarding your thoughts, if I may...
:nerd:
Your observation about capacity lost in a seaway is spot on. I know a guy that once had multiple air intrusions into his diesel supply line on a rough trip down the WA coast due to this. He was able to purge the line each time but it was very difficult. Bad planning for not carrying enough "extra" fuel.

And then there's the routing of the vent hose. Our model has the fuel tank under a settee rather than behind or beside the engine compartment which exacerbates the problem greatly. Our vent line runs from the port side settee aft, rising somewhat to be clipped up to the deck level at the cockpit and then down slightly to a metal "vent fitting" on the transom, near the top. This puts it in a plane just a bit lower (!) than the actual deck fill which is ahead of the port side chainplate location. I had to learn early on never to fill the tank all the way to the fitting and to stop instantly when the sound of the "gurgling" rises in pitch... that, and to have Kathy watching the tank gauge and calling out the change in readings. All this hassle for a 14 gallon tank. There were several times where a moment's hesitation at the fuel saw some diesel pushed out the vent.

At least we never had to worry about a "plug" in that line, just a lot of diesel laying in the sags in the hose routing.
One time we were motoring in big seas down by Astoria, heading for the West Basin marina and that darned vent was putting out a spoonful of diesel for a while every time the bow would ride up a wave.
"That's just Not Right" as the saying goes.

As a part of the changeout to the larger new tank, I replaced all the hoses. The new vent hose was routed to a shiny new fitting on the inside of the cockpit near the top of the front port side combing, above the bridge deck. Even this, location, over a foot higher than the transom, can push out a tiny bit of diesel if I got too aggressive in filling that last bit of the hose leading down to the tank -- but this has happened only once.
This was worked well, though, since we just place a paper towel under that vent and can be assured that any fuel that does emerge will not go into the sea. Kathy still watches the gauge when I fill and calls out the progress of the needle.
As Bob has pointed out, having a electronic gauge right on the panel by the breakers is way better than removing cushions and a wood cover to read that old dial on the top of the tank.

As for those new style service-station hose nozzles, I have yet to see one at a marine fuel dock on the Columbia or when we went North to Puget Sound in 2014.

Regards,
Loren

 

[supersailor]

Hi Tom.

I'm not sure the tank capacity is being overthought. I paid for an accurate measurement of the tank to get an accurately calibrated sender. The Engineers computer calibrated to the hundredths so I merely reported the results. The problem here is that many owners are reporting capacities far short of the actual capacity. I don't think Ericson put a lot of different size tanks in these boats. Therefore, their tanks aren't filling all the way up. That means that filling the tank to prevent condensation won't work. The owners really need to be using an emulsifier to keep the water in suspension during the winter or be draining the tank. That would work for me as I have a diesel van.

The fuel tank is the one bad feature I have found in this boat. I don't like the idea that a leaky fuel fill, vent or pickup/return could potentially dump up to 14 gallons of diesel in the bilge. If my tank wasn't filling all the way up, it would be tempting to leave it at half a tank to eliminate the possibility of this happening. The automatic bilge pump would pump about 10 gallons into the marina making the Harbormaster very unhappy. It would have been much better if Ericson had made the rear tank a water tank and made one of the saddle tanks the diesel tank like in the 36RH or the Olsens. It would have made the original installations more difficult but been much better down the road. 14 gallons of fresh water in the bilge is not a daunting experience. Bringing all the tank cutouts into the side of a fuel tank is just plain bad design. Would I give up a otherwise almost perfect boat for this? Hell no, but it is something to worry enough about to check on a religiously regular basis.

What happened with my little story was I took off on my very first cruise 4 days after I took possession of the boat. Before I left, I cozied up to the fuel dock and filled it up to the brim. That was a little over two gallons. At that point, I had not yet found the fuel gauge. We took off from Port Angeles to Port Townsend about 30 miles both sailing and powering. The next morning, we left and powered to the Port Townsend cut where the engine quit acting like it was fuel starvation. at Port Ludlow, we pulled up to the fuel dock and it took 1 gallon before overflowing just like the morning before. Two hours later it quit again in the Agate passage once again acting like fuel starvation. Hmm Put 1 gallon in. That's two hours of running at 1/2 gallon an hour. After being towed into Poulsbo, a look in the tank showed zero fuel. The trouble shooting showed a totally plugged vent. The problem was a completely plugged screen. The temporary solution was to take a Phillips head screwdriver and poke out the screen. The Poulsbo fill up after that was 28 gallons. The fuel fill has a fairly deep bow in it and I am hypothising that the pressure buildup in the tank was allowing only a trickle to flow into the tank while a whole bunch was going into the filler. That vent is mighty important.

 

[Christian Williams]

From a recent marine survey, under "Finding and Recommendations" :

9) The fuel tank vent line should stay level or above the tank as
it runs aft. A dip in the hose may hold fuel and prevent proper
venting.

And no, in Los Angeles we don't have those fancy nozzles, either.

By the way, this entire thread says to me: throw away the fuel gauge. Feel good about yourself again!

 

[Loren Beach]

A thread this informative & with humor for seasoning deserves a 'bump'.
(IMHO)

Newer site members probably will have questions about fuel capacity and system maintenance, and consequences.

 

[nquigley]

Does anyone know of a way to determine when fuel has completely filled the boat's tank (virtually no air pocket left), and is just starting to come up the hose connecting the tank and the deck-fill hole?
Is there some clever little device we can let down into the filler hose (after pausing fuel delivery) to tell when fuel is starting to come up that hose?

I think most of us would like to be able to fully displace the air layer above the fuel level in the tank, and get the tank as full as possible for max motoring range, but we can't completely trust the accuracy of our fuel gauge, so we err on the safe side by a large margin to prevent creating an over-fill spill on deck. And, if we're filling at a marine filling station, we might add an extra safety margin because they have a much higher delivery rate than if we're siphoning from a Jerry can.

 

[Christian Williams]

If needing a 100 percent full tank (which few ever will) I watch till fuel comes out of the air vent. Yeah, I know.

When in doubt of fuel level I remove the fuel sender and observe the level in the tank. And measure with a stick. (The stick still doesn't give you "gallons remaining," just a useful visual reference).

I use the hour meter to compute fuel remaining, estimating a burn of 3/4 gallons/hour. Usually the 5432 burns less than that. In aviation nobody trusts fuel gauges, it's always flight planning by fuel burn. A fuel gauge is definitely a convenience for us, though.

One thing to note during maximum fueling is whether the sender port will be "underwater." Mine is, since the tank tilts down a little fore and aft.

If so, the five-screw sender, with its ancient gasket, can leak when the tank is topped off. * If it does, a new gasket may be required, or a dab of gasket sealer. If the sender has been removed repeatedly over the years, the screw holes may be loose. Moving up to the next size self-tapping screw solves that.

*And then it's too late--so confirm a good seal before topping off.

 

[nquigley]

Good points, Christian. Thanks.

 

[supersailor]

Where it gets cold and damp (here it is 28 degrees with a strong wind and about 80% humidity) it is good to have the tank topped all the way up to stop condensation from forming in the tank. After a damp winter, it's amazing how much water appears in the tank. The 34's tank is not easy to get to to clean.