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Username Post: 1975 C30 Fuel Tank Diagram        (Topic#353890)
Thumpit 
Poster
Posts: 64
Thumpit
Reg: 11-26-16
11-13-18 11:02 AM - Post#2751272    

Going to change out the fuel tank and sending unit as well on my 1975 C30 flat bed. Tank is on the passenger side. Gauge used to work until gas fell below 1\2 a tank, then it showed 1\2 till you ran out. Doesn't work at all now. Plus i took the tank off once to clean it and do a small hole repair and did not hook any of the wires back on the tank. Tired of leaking tank and no gauge. So I order a new set up.
Does anyone have a wire diagram for hooking up the sender with the wire or wires under the cab? Cant be over two or three. I don't remember.
Thanks for the help



 
junkman104 
Frequent Contributor
Posts: 1357
junkman104
Age: 60
Loc: Murphy N.C.
Reg: 01-25-14
11-13-18 05:17 PM - Post#2751309    
    In response to Thumpit

Purple goes to gauge and black to ground, thats it.



 
gchemist 
Senior Chevytalk Moderator
Posts: 24690
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
11-14-18 05:18 PM - Post#2751414    
    In response to junkman104

Go here and download a factory manual for your truck.

http://forum.73-87chevytrucks.com/smforum/index.ph...

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles


 
Thumpit 
Poster
Posts: 64
Thumpit
Reg: 11-26-16
12-03-18 01:26 PM - Post#2753210    
    In response to gchemist

The single wiring plug that snaps down the sending unit is missing. Does anyone still make that end of the wiring connection or is there a way to make a connector that will work well. On the sending unit is just a single pole that the connector would attach to. I couldn't find an old truck to get one off.
Thanks



Edited by Thumpit on 12-03-18 02:01 PM. Reason for edit: No reason given.

 
gchemist 
Senior Chevytalk Moderator
Posts: 24690
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
12-03-18 03:19 PM - Post#2753225    
    In response to Thumpit

I have not looked at a fuel sending unit in years. Can you post a pic?

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles


 
junkman104 
Frequent Contributor
Posts: 1357
junkman104
Age: 60
Loc: Murphy N.C.
Reg: 01-25-14
12-04-18 05:37 AM - Post#2753298    
    In response to gchemist

https://www.ebay.com/itm/Gas-Tank-Fuel-Sen ding-Unit-Pigtail-Wire-Ha rness-Connector-A-C-Compr essor-Chevy-/302628787151





 
gchemist 
Senior Chevytalk Moderator
Posts: 24690
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
12-04-18 07:14 AM - Post#2753306    
    In response to junkman104

Nice find. Eventually, I'll need to replace on unit on my truck. One tank reads off by a little.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles


 
Thumpit 
Poster
Posts: 64
Thumpit
Reg: 11-26-16
12-04-18 08:15 AM - Post#2753315    
    In response to junkman104

Thanks.
The guage has always read from full to 1/2 a tank and then stopped at 1/2 a tank on the guage. I put a new tank and sending unit. I made a temp connector and hooked it up and the guage is still on 1/2 though the tank is empty right now.
Not sure if the guage need recalibration or fuse is blown.
Is the 'cluster fuse' where the guage gets it power?
I probably need to use a meter to check wires too but not to sure how to operate one.
Thanks again



 
gchemist 
Senior Chevytalk Moderator
Posts: 24690
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
12-04-18 09:13 AM - Post#2753324    
    In response to Thumpit

Did you download the factory manual? I think it has ohm readings for level indication.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles


 
Thumpit 
Poster
Posts: 64
Thumpit
Reg: 11-26-16
12-04-18 10:24 AM - Post#2753333    
    In response to gchemist

I could probably find the readings on line. But with a meter I would like to test the hot wire (which is a 18 Tan according to my 75 wiring diagram) to check for power at the tank.
Would it just put the Hot lead on the Tan wire Connector and ground the Neg to the frame? And then put the settings on Oms?
Thanks



 
junkman104 
Frequent Contributor
Posts: 1357
junkman104
Age: 60
Loc: Murphy N.C.
Reg: 01-25-14
12-04-18 05:05 PM - Post#2753378    
    In response to Thumpit

The sending unit is the ground. Shorted to ground the gauge should go past full.



 
Thumpit 
Poster
Posts: 64
Thumpit
Reg: 11-26-16
12-04-18 07:09 PM - Post#2753394    
    In response to junkman104

Thanks for the help. Im probably doing this all the hard way but will know better the next time.



 
Thumpit 
Poster
Posts: 64
Thumpit
Reg: 11-26-16
12-07-18 07:42 PM - Post#2753810    
    In response to Thumpit

Thanks for the tips. Got here working again.
Thanks



 
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