Join Date: Oct 2009
Location: northern california
Feedback Score: 0 reviews
Hey Snotz, yeah I kinda figured that.
But the fact that the gauge swings around wildly indicates at least one more problem. It could be in the tank sending unit, it could be a short in the chassis wiring, or it could be in the instrument panel.
If I was working this problem on my Toyota, I would look at the service manual p. 17-29 which has a little table that shows the (Toyota) sending unit puts out 3 ohms @ F, 33 ohms @ 1/2 tank, and 100 ohms @ E. So I then attach a 33 ohm resistor to the sense wire (removed from the sender at the top of the tank) and ground the other resistor lead. Then the gauge should read 1/2 tank. If it does and doesn't swing wildly when the truck bounces around, then the problem is in the tank. If it doesn't read 1/2 tank, the problem is in the wiring or instrument panel. If it reads 1/2 tank but swings when the truck bounces, I've got a chassis wiring short. (And I can use the 33 ohm resistor at the gauge in the instrument panel to further isolate the problem if necessary.
BUT WITHOUT THE TABLE IN THE MANUAL I"M SCREWED.
Anyone, how about some help? What are the wire colors and locations, and what is the relationship between tank level and resistance in the sending unit for my Ford?
Jim Jim Jim
-- 1988 F-350 (type F379) 7.3 NA diesel ZF5 4.10 DRW 11' service body
-- 1981 Toyota pickup 2.2L diesel 5-speed LB
-- 1980 Mercedes 300SD 3.0L turbo AT
Last edited by jim x 3; 11-05-2009 at 12:36 AM.