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mid cabin - fuel sending units

Posted: Wed Apr 12, 2017 11:29 am
by BobCT
I'm in the process of replacing both now. Here's what I know so far and pic of the Stb side hole cut out. I wanted to go as small as possible given the location and the likely hood that it will be years before I need access again. So, I'm using a 3.5" flush cover plate instead of a deck plate with a flange. It's just a flat piece of plastic with four screw holes. I sealed up the balsa coring and will drill/fill epoxy for the screw holes. The small size means you have to cut a pretty precise hole but the diameter of the sending units are really small. If you're more inclined to go with a deck plate, 4" is plenty big.

I'm using 22" Moeller mechanical arm sending units which are a hair longer (about an 1") than the original units. I'm also replacing the conversion capsules which sit on top of the sending units. That's the part that magnetically calculates the level and sends that signal up to the gauges. Credit Todd Pote for explaining that to me last year. The add'l length should not be a problem unless the arm actually bottoms out on the tank AND I ran until almost empty. I'm never under a 1/4 so I'm not worried about that. I even considered going with a 17" which would give a much bigger reserve.

I'll update with some dimensions when I'm done.

Bob

P.S. - that's a sledgehammer holding the cover plate down until I can do the install
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Re: mid cabin - fuel sending units

Posted: Wed Apr 12, 2017 12:02 pm
by prowlersfish
If you haven't bought the sender yet look at WEMA senders , A better mouse trap IMO

Re: mid cabin - fuel sending units

Posted: Wed Apr 12, 2017 12:26 pm
by RWS
I totally agree on the WEMA !

if you are going to do this, the WEMA allows you to do it once and THATS IT - like FOREVER


RWS

Re: mid cabin - fuel sending units

Posted: Wed Apr 12, 2017 12:40 pm
by El L Sea
I spent a full 5 minutes staring at that picture until I read the P.S. part to figure out what that was! :lol:

Re: mid cabin - fuel sending units

Posted: Wed Apr 12, 2017 5:21 pm
by BobCT
Unfortunately, I bought these late last year so it's too late to return them. Yeah, those so seem a lot less complicated than a pivoting arm. Although, the mechanics of the old ones seem perfect. I think the issue is just the weight of the float(s). The old ones are noticeably heavier than the new ones.

Re: mid cabin - fuel sending units

Posted: Sun Apr 23, 2017 10:40 pm
by yorklyn
I know you already know this Bob but I'm going to mention it anyway. Be sure to seal up the balsa core material after you cut the hole. Mine was done less then perfect and was very rotted.
Todd

Re: mid cabin - fuel sending units

Posted: Mon Apr 24, 2017 6:29 am
by RWS
Hey Todd.....


Miss us yet ?

RWS

Re: mid cabin - fuel sending units

Posted: Mon Apr 24, 2017 7:47 pm
by yorklyn
Absolutely Harris! I will try to update my old "renovation" post with an update on my current situation so you guys can laugh your asses off at me. I'll give you a hint, it's brand new, it's currently being built for me and it floats.

Re: mid cabin - fuel sending units

Posted: Tue Apr 25, 2017 5:45 pm
by BobCT
Here are a couple of more pics. One is the "conversion capsule" which attaches to the top of the sending unit with two small screws. The conversion capsule uses a magnetic signal to interpret the physical location of the float and send that information up to the gauge. If you are replacing the original unit, you will need to run a new ground wire, the original only has one wire. The pic shows the new and old units upside down. On the other side is a functioning gauge. In a pinch, you could check this gauge if there was an issue with the gauge or wiring from the sender up to the helm. Moeller sells the conversion capsules but they're made by Rochester gauges.

I replaced the factory senders with Moeller 22" units which are slightly longer than the originals. Some people have noticed a difference in length between the two tanks. I did as well but it was only about 1/2"- 3/4". I used 22" on both sides. The factory floats were cork and definitely giving me flaky readings because they were satured. A better option might be the WEMA senders.

As other people have posted, it is imperative that you seal the balsa coring all around. If you have an access or deck plate already installed, I would make it high on the list of things to check. My deck is bone dry and I plan to keep it that way. I'll do another update when I remember to add some measurements for the hole.

The second part of this project is installing Racor LG-100 units in both vent lines. These prevent fuel from overflowing out of the vent lines when filling up and provide positive shutoff (like a car) if filling to the top. This happened to me twice last year because of my gauge issues.
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Bob

Re: mid cabin - fuel sending units

Posted: Thu May 04, 2017 7:51 pm
by zedtwentyate
Looks great Bob. Now that I have my tank out I need to replace mine as well. I'm looking for some specs on it. I see you didn't go WEMA. Should I be doing that instead of the traditional? Any idea on what model I would need?

Re: mid cabin - fuel sending units

Posted: Thu May 04, 2017 8:47 pm
by BobCT
I just used the Moeller 22" mechanical units since I already bought them. The Wema units are vertical rather than a hinged arm and a few of the guys here swear by them. I think it's just a matter of finding the right height (depth of the tank on those).

Re: mid cabin - fuel sending units

Posted: Thu May 04, 2017 9:35 pm
by zedtwentyate
BobCT wrote:I just used the Moeller 22" mechanical units since I already bought them. The Wema units are vertical rather than a hinged arm and a few of the guys here swear by them. I think it's just a matter of finding the right height (depth of the tank on those).

Thanks Bob. I thought I read something about needing the correct resistance for the gauge to read right. Am I thinking of the right thing? I tried searching but didn't turn up what I thought I read.

Re: mid cabin - fuel sending units

Posted: Thu May 04, 2017 11:24 pm
by RWS
WEMA +100!

google it

RWS

Re: mid cabin - fuel sending units

Posted: Thu May 04, 2017 11:43 pm
by captainmaniac
Don't want to derail or post irrelevant content, but I have used WEMA to replace a fresh water tank sender. Gotta give a huge thumbs up for the company and their products.

A few years back I ordered from a 'local distributor' and waited 4 months for parts to show up... They blamed the 'sales guy'. Finally got p-o'd enough to call WEMA directly and ask to speak to the owner. A few minutes later I was talking to the owner (who was on the golf course...). 2 days later the parts I needed were delivered to my door, direct from the manufacturer. And they worked perfectly!

Re: mid cabin - fuel sending units

Posted: Fri May 05, 2017 12:08 am
by zedtwentyate
RWS wrote:WEMA +100!

google it

RWS

I did google it. I'd like to buy one rather than the traditional style. Just curious if there are specifics for our vessels.