Guys, I went through many site, vendors, and used parts guys before finally deciding to drop my search for NOS fuel sending units.
After some quick measurements, I found the total vertical movement needed was right around 9.5 inches (top of tanks mounting surface to the bottom of the tanks centered, small, circular bulge). Based on that, I ordered a Moeller Marine 9" Fuel Sending Unit, which is stainless steel construction and calibrated to 33-240ohms, which is compatible with the fuel gauge:
Product Description: 9" Reed Switch Sending Unit Tank Depth - Product # 035761-10. It's a little pricey, but I found a good deal at Amazon and, when compared to the price for a used, or if you could locate one, a brand new unit, I thought it was a great deal. Add to that the convenience of being able to order replacement units at a local store, and it's a no brainer. I pulled the tank; had it boiled out and sealed; while the new sender was on order.
See Photo 1 below.
I stated by fabricating an aluminum adapter plate, and drilling and tapping 5 holes (8-32 worked for me) in it for the sender. Note, the sender thru-hole, and associated 5 mounting holes, must be offset slightly (1/2") due to baffling at the bottom of the tank. When you test fit the sender, it will be obvious which direction, and how much you need to offest sender in the adapter plate. Use the sender's gasket to mark your 5 holes. The 5 screws I used are SS set screws and I had written down the sizes back when I made the mod, but can't find the sheet (found them: they were 8-32, but you could use metric equivalent). No worries, as this is a very simple mod.
See Photo 2 below.
Once you have drilled and tapped for set screws at the sender, mount the sender and check for fit. You then drill 5 thru-holes (1/4") for self tapping screws to mount everything to the tank. When final fitting, it may be necessary to shift the aluminum plate around some just to be sure the float isn't bottoming on a baffle. When you've got it located, remove the assy and drill holes through the top of the tank, corresponding to the holes in the adapter plate, and mount the sending unit's adapter plate to the tank. Be generous with the sealing compound. I did not use a gasket. Here's what you should end up with:
See Photo 3 below.
Now, you can install, for the last time, your Moeller Sending Unit and wire the unit in. I used ss nylon nuts to secure the sender, with loctite on the adapter end. I also checked operation of the unit before final wiring, and the gauge worked perfectly, with much quicker response time than the original unit.
See Photo 4 below.
And here's the final installed unit. It fits nicely under the sheetmetal, is made of stainless steel; it's calibration is spot on with no "catch up" cycles from top mounted pivots; and I can buy a replacment at any local marine store.
See Photo 5 below.
I hope you found this tech tip useful and here's a closer shot of what my unit looked like when finished:
See Photo 6 below.
S
Topic: Caddy Fuel Sending Unit Upgrade (Read 4547 times)
