Tweet
I'm refinishing a 70's style gas tank and wanted to know how the fuel float works electrically? I would like to test its operation before I put it back on since I can't reach it once it's installed on my truck. How would I test this float unit. From what I've found it is the 1970-1979 style unit WITHOUT the integral fuel pickup. http://www.teamgrandwagoneer.com/par...ailed/744.html . When I pulled the tank off there was no wire attached so I have no prior history to tell of the units operation. And also I don't know the status of the dash cluster (the speedo works at least) so I've got to start somewhere and since I have the tank out. Thanks.
-
1965 Kaiser Jeep Wagoneer Custom w/327 Vigilante, TH400, and Tulsa PTO winch. All original. All broken. -
Electrically it's a variable resistor, aka rheostat. The resistance changes as the fuel level falls. The usual failures are that the resistance element goes open, or that the float gets a hole in it and sinks. On the later models, the expected resistances are given in the FSM. A single wire goes to the post on the top, the circuit goes to the wiper contacting the resistor and the resistor is grounded through contact with the tank. The wiper moves along the resistor as the float rises and lowers.
Test it using the resistance scale on your multimeter.Last edited by tgreese; 11-07-2006, 11:32 AM.Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
ECO Green: '15 FCA Jeep Cherokee KL Trailhawk -
The specs for the 70-79 era is 73 ohms at Empty and 10 ohms at Full.joe
"Don't mind me. I'm just here for the alibi"Comment
-
Just attach the ground to anywhere on the tank (bare metal) or does it need to be near the sending unit?1965 Kaiser Jeep Wagoneer Custom w/327 Vigilante, TH400, and Tulsa PTO winch. All original. All broken.Comment
-
The whole tank is grounded, but you'll want to take the sender out of the tank and look at it. Test from the post to the metal base that touches the tank, then move the float arm. IIRC there's a locking ring and an o-ring under the sender.Originally posted by 70sWagoneersTim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
ECO Green: '15 FCA Jeep Cherokee KL TrailhawkComment
-
if you use an analog ohmmeter to test as you move your float through its paces the needle on the ohmmeter should steadily climb if it spikes or drops as you move the float you might as well throw the send unit in the trash - IIRC the 10/70 is a common Ford fuel sender rating.Jeff - 74 Cherokee S 401/400/QT - basically stock
Comment
-
Zeroed my multimeter and tested the resistance. I got about 23 to 90ohms with no spikes. Good? Bad?1965 Kaiser Jeep Wagoneer Custom w/327 Vigilante, TH400, and Tulsa PTO winch. All original. All broken.Comment
-
Connections At the Top of the Fuel Sending Unit?
When replacing the fuel sending unit in my 89 Grand Wagoneer the tab at the top of the unit that inserts to a female electrical connector broke off with the old unit. There are two connections at the top, one is a post with a cap that fits over it, the other is the tab with a female connector that slides over it. Anyone know what this tab is for? Is the post the grounding wire and the tab connector the signal for the fuel gauge?1989 Grand WagoneerComment
-
Did you ever find out which connector was ground?Originally posted by jtrainComment
Comment