CONTINUOUSWAVE

I have a 2004 17-foot Boston Whaler boat. Can the Moeller 22-gallon white top side tank fit under the seat of my boat?

I am assuming you are referring to the 22 gallon above-deck fuel tank that has a model no. of 031626BR. It's dimensions in inches are 29-1/4 L x 20-1/2 W x 14 H with the cap installed. It is marketed as a replacement for 15-foot and 17-foot Boston Whalers. I know that it fits under the reversible pilot seat of a 1986 Montauk. I would measure your space and compare to the dimensions posted.

JOHNW--thanks for digging up the dimensions of the Moeller 22-gallon on-deck fuel tank.

Thanks Johnw, at the moment I do not have access to my whaler. I wanted to see if anyone had installed the top side tank in a similar year whaler, being that I am unable to take a measurement.

Yes - I have installed that tank on a 2003 and 2005 170 Montauk:
http://s166.photobucket.com/user/joseph ... t=3&page=1

Lot of discussion in the old forums on this tank:
http://continuouswave.com/ubb/Forum1/HTML/018886.html

BTE - Please state the model you have. Big difference between a Montauk 170, Dauntless 170 et. al.

Phil - I assumed since it's a 2004 and the only 17' foot boats BW made were the 170 Montauk and 170 Sport - that the reference was to the 170 Montauk. The 2004 Dauntless was a 16' footer ;).

It looks like the mounts for that tank would miss screwing into a proper wood surface according to the wood locating diagram. Do you recall hitting wood or is it just screwed into the foam and non-skid?

Correct - I have the brackets screwed into just the deck (no wood), but I did bed the screws and brackets with 3M4200. After seven years of heavy and rough use, mostly water sports so a lot of stress with a full tank in quick turns - jumping on plane - wake jumping, ect, I have not had any problems. I have had replaced the filler neck fuel cap/gauge twice.

Ridge Runner, thanks! That is exactly what I was looking to see.

JohnW, you mentioned if fits perfectly on your 1986 Montauk. Were you able to use the original opening/tunnel access for the fuel line? After reading the long discussion about this tank on the old forum, there seemed to be conflicting reports if that was possible or if a new access hole to the rigging tunnel needed to be drilled.

Ridge Runner wrote:Correct - I have the brackets screwed into just the deck (no wood), but I did bed the screws and brackets with 3M4200. After seven years of heavy and rough use, mostly water sports so a lot of stress with a full tank in quick turns - jumping on plane - wake jumping, ect, I have not had any problems. I have had replaced the filler neck fuel cap/gauge twice.

I had the same experience on a Montauk 170. The front tank screws hit wood and the rear did not. I also used 3M4200 and is holding fine.

I used this type of strap kit to hold the tank in. It makes it easily removable and a clean installation.

http://www.marine-products.com/moeller-hold-down-strap-kit-035711-10.html

This picture was before the straps were installed. The EPA compliant version of the tank is red. I ran wires to the console in case I wanted to add an electric sending unit later, but have not done that.

I've been told that my Mercury 90 FOURSTROKE BASED ON 2.1-LITER won't run properly without the new EPA venting do-hicky as found on the standard 6 gallon fuel tanks. Does this new vent come standard on the Moeller tank?

How could the engine possibly know what sort of fuel tank it was connected to? About all the engine sees from the fuel system is a certain amount of fuel flow for a certain amount of vacuum suction on the fuel line.

Whatever someone told you about an "EPA venting do-hicky" was probably just a simplification of the principle that the fuel lift pump in ANY engine cannot pull fuel from a fuel tank that is not vented. There is a limit to how much pressure drop can occur in the fuel line. A sealed tank won't work.

The EPA is not concerned with the atmosphere entering the fuel tank. The EPA is concerned with vapors from the fuel tank entering the atmosphere. The vent on the fuel tank just needs to have a check valve so it only vents in one direction: atmosphere into the tank, not the other direction. That is probably what was meant by "EPA venting do-hicky."

JM3 wrote:I've been told that my Mercury 90 FOURSTROKE BASED ON 2.1-LITER won't run properly without the new EPA venting do-hicky as found on the standard 6 gallon fuel tanks. Does this new vent come standard on the Moeller tank?

No extra vent came with the Moeller EPA rated tank. I used the venting do-hicky off the stock 6 gallon tank.

This discusses the 'fuel demand valve' (do-hicky)

https://www.quicksilver-products.com/en ... uel-tanks/

This is Mercury's way of getting people to but their brand of accessory portable tank.

Any EPA compliant marine portable fuel tank will work.

JM3 - Using the phrase "I was told...." without stating who the person was that told it is a sure sign the information should be highly discounted.

Does one honestly believe that Mercury would engineer an outboard that would only work with their proprietary tank?

Phil T wrote:This is Mercury's way of getting people to but their brand of accessory portable tank.

Any EPA compliant marine portable fuel tank will work.

JM3 - Using the phrase "I was told...." without stating who the person was that told it is a sure sign the information should be highly discounted.

Does one honestly believe that Mercury would engineer an outboard that would only work with their proprietary tank?

It does not need a proprietary tank. The valve is recommended to keep from pushing fuel into the engine with tank pressure. That is since EPA tanks don't have open vents.

Phil T:
"Does one honestly believe that Mercury would engineer an outboard that would only work with their proprietary tank?"

Well, their parent company is interested in forcing customers to buy proprietary outboards with their boats, so yes. Yes. I honestly believe that if they could get away with it, Mercury would absolutely engineer an outboard that would only work with their proprietary tank. I don't think they have...but I think they would if they could. Yes, Absolutely. Without a doubt.

It sounds to me like the requirements of the EPA dictate how "the new EPA venting do-hicky" operates, not anything dreamed up by Brunswick's engineers. I suspect that any on-deck fuel tank being sold under the labeling of meeting current EPA requirements will probably have "the new EPA venting do-hicky".

You really do not want to allow a build up of pressure in your on-deck fuel tank to force fuel through the fuel system of your outboard engine and lead to the fuel spilling into the water. That is also an EPA violation and can result in a fine.

And thanks to TIMF for the pointer to more details, about "the new EPA venting do-hicky". I did not realize that the EPA would permit the tank to vent to the atmosphere when the internal tank pressure was 5-PSI greater than atmospheric pressure.

In this discussion there are two sets of interesting numerical values mentioned. First we have the dimensions of the Moeller 22-gallon on-deck fuel tank in inches: 29-1/4 L x 20-1/2 W x 14 H with the cap installed. Let us suppose the cap represents about 2-inches of the height and that the wall thickness is perhaps 1/8th-inch. This suggests that the surface area of this tank's internal walls will be about

2 x 29 x 14 = 812 (short sides)
2 x 20 x 14 = 560 (long sides)
2 x 29 x 20 = 1160 (top and bottom)
TOTAL AREA = 2,532-inch-square.

Second, we learned that the "the new EPA venting do-hicky" permits a build up of pressure in the tank to 5-PSI before releasing the pressure to the atmosphere. We can calculate the total force being exerted onto the tank walls by using the force per square-inch and multiplying by the number of square-inches:

2,532-inch-square x 5-lbs / 1-inch-sqare = 12,660-lbs.

Darn, but that is a lot of force exerted on a plastic fuel tank. Moeller must be making the tank using some very strong plastic polymers if the tank can withstand that sort of force being exerted on its walls without rupturing them.

The tank has some type of coating on the inside. It is a brown color and can be seen when the cap is off. I was assuming it was to help stop vapors through the walls, but likely adds some strength as well...

I have a 1991 Montauk, and just put the 22 gallon white Moeller tank under the RPS. It fit perfectly, doesn't block the hole for the fuel line, and the bungee cords that were already in place to hold the previous 6 or 12 gallon tanks, fit perfectly over the 22. And it looks great!

I just installed the white model of this tank over the weekend on my 1984 Montauk. If the tank was placed far enough forward to clear the opening in the deck for the fuel hose, the tank cap couldn't be removed as it was blocked by the bottom of the seat. I had to install the tank by resting it on two pieces of Starboard to provide clearance for the fuel hose (I didn't want to drill/cut a new opening in the deck). I'm guessing the opening to the rigging tunnel for the fuel hose is further aft on the 1991 Montauk than my 1984?

By the way, Moeller refers to the white model of this tank (part number 031626) as the "non-barrier" version. To my surprise this tank shipped with a Kelch fuel cap which features an open vent, and interestingly the tank is not listed under the "US-EPA compliant" section of Moeller's website, it's listed under the "International use only" section.

Jon