87MJTIM Posted July 23 Share Posted July 23 I was looking under my 87 for something unrelated to what I found today. I saw wire on the fuel pump (FP) not connected to anything. The harness has 3 wires: orange and purple connecting to the pump, and a naked black wire (see picture). The 87 wiring diagram shows just 2 wires at the FP: 1 orange and 1 black. The connector diagram shows the C305 as having one wire and the C306 have a flat, blade connector. What is the purple wire? Where does the black wire connect? There is no other connector visible, screw to attach a flat connector. Link to comment Share on other sites More sharing options...
87MJTIM Posted July 23 Author Share Posted July 23 Additionally, the fuel gauge works fine. Link to comment Share on other sites More sharing options...
eaglescout526 Posted July 23 Share Posted July 23 Did the flat blade soldered to the sending unit rust off and away? Link to comment Share on other sites More sharing options...
derf Posted July 23 Share Posted July 23 Purple wire is likely the sending unit wire. They're together in the tank. Link to comment Share on other sites More sharing options...
JZLAJeep Posted July 23 Share Posted July 23 1 minute ago, 87MJTIM said: Additionally, the fuel gauge works fine. As I learned on the farm, "we don't fix things that work." Link to comment Share on other sites More sharing options...
87MJTIM Posted July 23 Author Share Posted July 23 That is very sound advice. I just want to make sure the black wire isn’t what’s holding everything together. Link to comment Share on other sites More sharing options...
Ωhm Posted July 23 Share Posted July 23 Wouldn't the black wire enter the tank using that grommet used by the other two wires? If so, then pump and gauge are finding ground thru the metal tank & straps. Link to comment Share on other sites More sharing options...
87MJTIM Posted July 23 Author Share Posted July 23 Winner winner chicken dinner I have a MTS fuel pump. Three wires at the connector. Looks like I need to change the FP. Link to comment Share on other sites More sharing options...
GonzoTheGreat Posted July 24 Share Posted July 24 Stock, the black wire has a female spade terminal, and there is a male spade terminal soldered/braised onto the sending unit flange for ground, like @eaglescout526said. Orange is pump + Purple is gauge sender I also had the black wire break on my '89, and somehow the pump grounded through the tank and straps, and it still worked Link to comment Share on other sites More sharing options...
87MJTIM Posted July 24 Author Share Posted July 24 4 hours ago, GonzoTheGreat said: Stock, the black wire has a female spade terminal, and there is a male spade terminal soldered/braised onto the sending unit flange for ground, like @eaglescout526said. Orange is pump + Purple is gauge sender I also had the black wire break on my '89, and somehow the pump grounded through the tank and straps, and it still worked Good to know it still worked through the tank/straps. The wiring diagram does not show the purple wire. That was puzzling me. Link to comment Share on other sites More sharing options...
Ωhm Posted July 24 Share Posted July 24 Check Instrument Cluster (fuel sender). Link to comment Share on other sites More sharing options...
87MJTIM Posted July 24 Author Share Posted July 24 Fuel gauge has worked fine. Link to comment Share on other sites More sharing options...
Ωhm Posted July 24 Share Posted July 24 Check Instrument Cluster (fuel sender) page in the Electrical Manual. Link to comment Share on other sites More sharing options...
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