J40 fuel tank

[Ken austin]

Hello fellow J40 owners,

Wondering if anyone has had experience adding an access port ( SeaBuilt) to their welded aluminum tank ? I have had engine issues which seem to be coming from dirty fuel that has been kicked up during off shore travels and am thinking of creating the access port to clean the tank. Also wondering if anyone knows if there were baffles in this version of the tank which is the standard 33 gallon one that came with original boat in 1989.

Appreciate any insights and thank you,

Ken
SV Mimosa
#58

[Tom Keffer]

The SeaBuilt access port is nice kit, but the pricing seemed excessive to me. So I built my own. 

https://threefools.org/velocity/Projects/DieselAccessPlate/DieselAccessPlate.htm

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[David Jade]

Tom - I just want to say, that backing plate solution is clever!

 

David             _/)

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[Ken austin]

Impressive indeed. 

Guessing it both solved your leak issue and allowed you to clean the tanks given how well planned it appears to be?

Was your J40 of a similar vintage and if so, do your recall if there were any internal tank baffles, other issues to keep in mind ?

Also any suggestions on location of the port even if you inherited yours?

Best , Ken 

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[Tom Keffer]

This was in a 2000 J/42. 

There is a single internal baffle.

The access plate has been leak free for over 15 years.

The location is not ideal: it doesn't let you reach all corners of the tank. I suppose I could add a second plate, but I really haven't found it necessary.

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[Larry Romano]

I have 1989,J40,#

A picture of the baffle

On Feb 15, 2026, at 9:38 PM, Tom Keffer <tke...@gmail.com> wrote:



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[Ken austin]



Sent from my iPhone

On Feb 16, 2026, at 5:40 AM, Ken austin <kdau...@gmail.com> wrote:

Hello - thank you very much for the input and photos Tom, David and Larry. 

Hopefully, I can report similar success. 

Appreciate the quick and helpful insights.

The group is a wonderful resource.

 Beat, Ken 

Sent from my iPhone

On Feb 16, 2026, at 5:04 AM, Larry Romano <j40r...@gmail.com> wrote:



I have 1989,J40,#

A picture of the baffle

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[Larry Romano]

Ken

Since you are working on the fuel tank, think about removing the tank so you can get access to the nuts and washers that hold the prop shaft strut in place. I found one nut so rusted it broke and all needed to be tighten. I replaced all of the nuts and washers.

Sailfast 

On Feb 16, 2026, at 8:44 AM, Ken austin <kdau...@gmail.com> wrote:



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[Walter Caldwell]

If you have an original tank made by Aluminum Fabricated Products in Florida and need a new one, RDS Aluminum can make one pretty reasonably. All they need is the serial number of the old one.  

Our old one developed a pinhole leak at the lowest point under the pickup. The replacement fit perfectly and was easy to install.  And it has an inspection port. 

[Ken austin]

Both good ideas and thank you, Ken 

Sent from my iPhone

On Feb 16, 2026, at 7:08 AM, Walter Caldwell <j40shaken...@gmail.com> wrote:

If you have an original tank made by Aluminum Fabricated Products in Florida and need a new one, RDS Aluminum can make one pretty reasonably. All they need is the serial number of the old one.  

To view this discussion visit https://groups.google.com/d/msgid/j4x-owners-group/04828070-36c4-4d0e-aca7-0fd27b91e950n%40googlegroups.com.