Wema sending unit fuel tank fix

[bigeasy1]

I had posted a while back that the dope that owned my boat previously,used sheet metal screws to hold the sending unit to the tank,and that a tiny amount of fuel was leaking around one screw.
As some of you mentioned,I also thought about redrilling and tapping out the holes to a larger size threaded machine screw,and even using some fuel proof sealant.I figured I'd use my air drill(no sparks)or maybe even my hand operated egg beater hand drill.

I called the tech guy at Wema,and he recommended up grading to a Viton gasket,instead of the cork one that came with the unit,and to get what they call an under ring,,which looks like a round horse shoe with an opening.It has drilled threaded (metric)holes to accept provided screws.
The trick is to get the ring up against the inside of the tank,and getting one screw started,so that it doesn't fall to the bottom of the tank.It then becomes a matter of lining up the remaining holes and getting the remaining screws installed.
Of course I would still have to drill out the holes,but only enough to get the new scews in to the ring.
I'm thinking about the best way of holding the ring while I get the screw in as I'll be alone when I'm doing it.I'm thinking possibly about some very fine wire or other means to work as a lifeline to the ring in case I drop it.

So, Any Ideas??? what do you figure the odds are that there's going to be an "OOPS" moment or a four letter rant session?

Here's a picture of it. the part # is FLSU



http://www.wemausa.com/sensors/adapters.shtml#Underring

[FLexpat]

Unless you secure it in place (epoxy or some attachment), this looks like a one shot deal; once it is on you won't be able to pull the sender later without dropping the ring into the tank...
I'm not a big fan of epoxy drooling into fuel tanks. Maybe add one or two very small flush screws through the tank into additional threaded holes in the ring? That way you can mount the ring first, the gasket would still seal and you may not cuss as much later. Still use a wire while you are doing it though. Be very careful about using a shop vac to pull the cuttings away, they make excellent ignition sources - don't ask how I know that...

[gofastsandman]

Originally Posted by FLexpat

Unless you secure it in place (epoxy or some attachment), this looks like a one shot deal; once it is on you won't be able to pull the sender later without dropping the ring into the tank...
I'm not a big fan of epoxy drooling into fuel tanks. Maybe add one or two very small flush screws through the tank into additional threaded holes in the ring? That way you can mount the ring first, the gasket would still seal and you may not cuss as much later. Still use a wire while you are doing it though. Be very careful about using a shop vac to pull the cuttings away, they make excellent ignition sources - don't ask how I know that...

Hmmm , that`s a pretty shade of blue. Don`t forget to tip your hard working pilots and stews.

You`ll need 2 long screws so you can hold the Wilbur shoe and have room to move things around. maybe 2 1/2 -3 ". Put these through the top of the sender, gasket, tank, and into the shoe. Use the long screws to line everything up. Pull long screws up and put short ones in.

Put a loop of light mono through the center hole of the shoe as an oh snap preventer. Remove before seating the wema.

GFS,
Chief Imagineer.

[Blue_Heron]

Originally Posted by bigeasy1

So, Any Ideas???

You're over thinking this. The Wema sending unit doesn't have to be aligned in a particular direction because the float isn't on an arm. Just rotate it 20° right or left so it covers the existing holes and drill/tap new holes. Piece of cake, no worries, etc...

Dave

[McGillicuddy]

Dave, I think Big John's referring to the screw hole alignment. The holes on the flange are not equidistant, so they will require lining up with the under ring. IIRC, the screw pattern is not an equilateral pentagon although it appears to be.

John, I think you could use a 1/4" wide strip of tin about 4-5" long, fold a hair-pin turn into one end, maybe 3/8" fold, and use that gap as a clamp. Maybe use two of them to keep the under ring level as you start 2 screws. Then slide tin strips out and tighten screws some, eventually, fitting the rest of the screws.

[NoBones]

Dental floss....

Been there done that!!!

[Blue_Heron]

Originally Posted by McGillicuddy

Dave, I think Big John's referring to the screw hole alignment. The holes on the flange are not equidistant, so they will require lining up with the under ring. IIRC, the screw pattern is not an equilateral pentagon although it appears to be.

Gillie. Dude,

Maybe my solution is so simple it's hard to understand. I know the screw pattern isn't symmetrical. That's so the float arm will point in the right direction and won't hit the side of the tank, or a baffle. But the Wema unit doesn't have a float arm and it doesn't care if it lines up with the original screw pattern.

If you rotate it a few degrees either way, so it no longer lines up with the wallered out (southern technical term) original holes, and drill and tap nice new holes, the flange and gasket will cover the old holes, and the nifty backup ring becomes unnecessary. This is what I did with both of the tanks in my Seafari, and they don't leak.

[McGillicuddy]

Originally Posted by Blue_Heron

Gillie. Dude,
Maybe my solution is so simple it's hard to understand.

Naw, Dave your solution was clear, and in fact that's exactly what I did. I was just trying to come up with a simple way to hold the snazzy Wilbur ring in place.

Just use a pneumatic drill to bore your tap holes, John.

[gofastsandman]

Originally Posted by McGillicuddy

Naw, Dave your solution was clear, and in fact that's exactly what I did. I was just trying to come up with a simple way to hold the snazzy Wilbur ring in place.

Just use a pneumatic drill to bore your tap holes, John.

Far better than boom.

Cheers,
GFS

[bigeasy1]

Originally Posted by McGillicuddy

Naw, Dave your solution was clear, and in fact that's exactly what I did. I was just trying to come up with a simple way to hold the snazzy Wilbur ring in place.

Just use a pneumatic drill to bore your tap holes, John.

Yep Gillie,that's what I'm going to use,I'll also bring my old egg beater style hand drill along in case I feel unsafe.
I may also put a piece of duct tape over the big hole for the sending unit to keep the bulk of fumes at bay or maybe a wet rag stuffed in the hole as Don V mentioned.
My thanks to all of you for the help with this..