Fuel sending unit question

[McGillicuddy]

My fuel sending unit readings are way off. In fact the Ohms read opposite what they shoud which leads me to beleive that someone bent the float wire the wrong way, and the Ohm range is far less than the current 33 to 240 Ohm standard.

I'm leaning toward a WEMA reed style sender to replace the old one.

Tank depth is 7-1/2". The actual float tube lengths are 1" less than the stated length.

So my question is do I opt for the 8" version which would leave a 1/2" of space and theoretically a more acurate reading or do I go shorter and know that I'll have just a bit more cushion when it reads empty? My tank also has tapered front bottom and rear top (72 Seafari) if it matters. Thanks for any feedback.

[Blue_Heron]

Gillie,
I believe the WEMA sending unit lengths are actual. You deduct 1" from tank depth for a plastic tank and 3/4" for a metal tank to get the length you need. It's all on their web site. I think you would be ok with a 7" unit. If you get an 8", it's not gonna fit.
Dave

[McGillicuddy]

Thanks, Dave.
Looks like the have half inch increments on their website. I think 6-1/2" model makes sense. $40 is a heck of a lot better than West Marine price.
Gillie

[Blue_Heron]

I got mine on ebay. $35.99 with shipping.

http://www.ebay.com/itm/Wema-7-sendi...57fccc&vxp=mtr

[McGillicuddy]

Thanks Dave. You think the 1/4" is worth sweating or will it just amount to understanding that when the guage reads "E" I'll be totally empty?

[76Red18]

Love the wema unit. No problems in 4 years. I'm pretty sure I went with a 7" for an 8" tank depth.

[Blue_Heron]

Originally Posted by McGillicuddy

Thanks Dave. You think the 1/4" is worth sweating or will it just amount to understanding that when the guage reads "E" I'll be totally empty?

Gillie,
I can't remember what I ended up doing. If I remember correctly (not exactly a safe bet), my tank depth was 11.5" and I got 11'sending units.
Dave

[eggsuckindog]

Run it until it hits E and stops moving completely - then fill it up or at least put the exact amout of 1/4 or 1/2 tank and see where goes, should be close.

[bobbert]

Good choice, have used them for years with no problems. As a plus they are a PLEASURE to work with, customer support outstanding. Just make sure you do not have a voltage drop in the wiring to the sender. Went nuts one year tracking that problem back to marginal ignition switch.

[McGillicuddy]

bobbert,
Thanks for the wiring reminder . I'll be sure to do the math but I think 16ga should be fine <-3% for the short roundtrip.