'97 Phord F150, fuel gauge no work....
08-22-2018, 10:58 PM
#1
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'97 Phord F150, fuel gauge no work....
I've got a '97 F250 that had a bad fuel pump. I dropped tank, replace fuel pump and tested before raising tank up into vehicle. Pump and engine ran great...but gauge doesn't work now; it jumps right to above full. Mitchell/ProDemand wants you to test the wire that runs from gauge to tank (yel/wht) for open. I've tested that wire every which way possible, including hooking 12v to the IP connector (disconnected from the IP) and lighting a bulb down by the tank to ensure continuity w/a load. There is continuity.
Another test is the ground; both the one at the sending unit (org/blk) and the one at the IP (pnk/org). Both are good.
Finally they want you to measure resistance through the circuit either with an empty tank, OR with a full tank. I don't "get" this test at all -although I ran the test with ~1/3 tank of fuel -what the truck has in it. Anyway, Mitchell says to test pin #5 (yel/wht wire) at IP connector, to pin 10 (pnk/org) at the same connector. On an empty tank, "If resistance is greater than 20 ohms, repair yet/wht wire or pink/Orange wire or replace sender. If resistance is less than 20 ohms, repair/replace cluster and printed circuit board." OR With a full tank; same connector, same pins, "If resistance is greater than 140 ohms, repair yet/wht wire or pink/Orange wire or replace sender. If resistance is less than 140 ohms, repair/replace cluster and printed circuit board." 1. how can a test spec be that specific, testing on "empty" (or full)?? 21 ohms and we have an "open"? 19 ohms and we have a bad gauge/cluster? I don't "get it". 2. It doesn't matter what I do with the wiring; I can disconnect the yel/wht wire, connect it, ground it...whatever, gauge rests below empty
but key on, it's going above full no matter what. 3. I've run redundant wiring for both the grounds and the yel/wht wires -no difference. 4. Mitchell says to disconnect the
-batt cable for 1 min if gauge doesn't work. I've done that 4 or 5 times at least. Each time I'm done testing I do it, just to be "sure". 5. Customer says the gauge worked when they dropped it off.
Thoughts? I'm totally lost.
Another test is the ground; both the one at the sending unit (org/blk) and the one at the IP (pnk/org). Both are good.
Finally they want you to measure resistance through the circuit either with an empty tank, OR with a full tank. I don't "get" this test at all -although I ran the test with ~1/3 tank of fuel -what the truck has in it. Anyway, Mitchell says to test pin #5 (yel/wht wire) at IP connector, to pin 10 (pnk/org) at the same connector. On an empty tank, "If resistance is greater than 20 ohms, repair yet/wht wire or pink/Orange wire or replace sender. If resistance is less than 20 ohms, repair/replace cluster and printed circuit board." OR With a full tank; same connector, same pins, "If resistance is greater than 140 ohms, repair yet/wht wire or pink/Orange wire or replace sender. If resistance is less than 140 ohms, repair/replace cluster and printed circuit board." 1. how can a test spec be that specific, testing on "empty" (or full)?? 21 ohms and we have an "open"? 19 ohms and we have a bad gauge/cluster? I don't "get it". 2. It doesn't matter what I do with the wiring; I can disconnect the yel/wht wire, connect it, ground it...whatever, gauge rests below empty
but key on, it's going above full no matter what. 3. I've run redundant wiring for both the grounds and the yel/wht wires -no difference. 4. Mitchell says to disconnect the
-batt cable for 1 min if gauge doesn't work. I've done that 4 or 5 times at least. Each time I'm done testing I do it, just to be "sure". 5. Customer says the gauge worked when they dropped it off.
Thoughts? I'm totally lost.
