proper sender for fuel tanks, ex-mod.

[cedryck]

Greetings, I am in need of a fuel sender for my second underseat tank. (65 ex-mod) was positive earth, now negative. I have tried fitting another type of fuel sender to that tank, and when I switch to that tank (tank is empty) gas needle jumps to full, tank is not full. My other tank, which does read properly, has a grey sender with a rectangle top, and only one connection for the green wire with black stripe. The other sender I tried, I think is a diesel sender with two tabs, one isolated, and another I think is for the low warning. I feel like I need the older looking grey sender with one hook up for the green wire with black stripe. Questions, are what is the proper type of sender for a 2a, exmod with two tanks? and Do those little switches on top of the switchover valve (conncected to firewall) go bad? Questions and comments welcome please.

[leafsprung]

Your senders and gauge need to match. Regardless of the actual polarity of your truck. If you have a late gauge you need late senders and if you have an early gauge you need early senders. The early senders typically use a cast housing with a bare aluminum finish and have a small cover plate over the rheostat, while the later ones are sheet metal and yellow zinc/cad plated. The early gauges typically have an arrow shaped needle while late ones have straight sides with no arrow head. The dual tank switches can go bad like any switch you need to test them for continuity. Let me know if you have other questions.

[cedryck]

Thanks Leafsprung, I have an early style, (brushed AL finish, with rheostat) which works on one side. Lovely. The yellow zinc/can does not. So it seems like you confirm what I suspect. I need another early rheostat style. Thanks for your reply.

[cedryck]

Leafsprung, what has been your experience with those little electrical switches atop the changeover valve? I did a test last night, and one is bad, I also discovered they are actually closed, until switch moves it to open when in contact. So I have ordered a switch, that and an old style sender, should help solve my problem.
Cheers,

[leafsprung]

I replace them as needed - they are pretty durable but they do go bad. Let me know if you need help finding the old sender

-Ike

[cedryck]

Thanks, will keep that in mind. Cheers, rover-on.