I have a new old sending unit/pump for my truck that came with it to fix the gas gauge, but I want to make sure this one works before I put it in. So I figure and ohm meter will tell me if the gauge works, and a 12v dc source would tell me if the pump works, but which connectors power what? And what resistance should I see at empty, 1/2 and full tank?

Thanks guys.

 

The FAQ in this section has the service manual that gives all the details on how to test it. But I wouldn't trust a used pump. If I were you I would get a new sending unit, so you know its new. Who knows how many miles are put on that pump and who knows how much more is left on it.

Or if your current pump is working good just replace the float. One member found a replacement part number and it is cheep. Go to the FAQ and it is listed there.

 

Well here's the issue, idk what the issue with the current sending unit is. I have heard there are several potential problems. I also don't have the $200+ for a new unit. I feel as though there is some way to remove the pump though. If I can do that, I could try and get some #'s off it and match it up to a replacement. It looks like I can get to it from the top, but what secures it to the plastic?

 

The best way is to remove the bed. A ground bolt, 8 frame bolts and a few plugs will make the entire job go smoothly and prevent a catastophic vernacular armagedon. The pump is in the base of the housing and easy to extract and replace. This is much easier than dropping the tank, plus you can identify issues with your chassis and replace your rear shocks easily if they require it. Issues with your bed can be resolved easily also.

 

I know how to get the whole assembly out, but I mean if I can find some way to separate the pump from the float/sending unit assembly I would replace the pump within the sending unit.

 

From what I saw online, it looks like you have a sealed assembly. You would need to "crack" the parting line and reseam, both of which require special tools. If it were a matter of cost, you could seperate the base (below the physical pump), service the pump, and reseal the base. I am not sure how confident you are modifying plastics though. It would be technically better to replace the unit.

EDIT after rereading original post.

If your only concerned with the sending unit, you can plug in the "new/old" unit that you have and move the arm with the key on without it being in the tank.

 

I do want to test the sending unit and the pump, I also would like to REPLACE the pump if I could without spending $200+, but I geuss I'll have to wait and see. For now, I just know when to fill it.

 

Well, I got the pump out. My new used sending unit/pump has the top screwed onto it, not one piece, so with a few screws the entire thing came apart, and the pump was in my hands just as I hoped/expected. Idk what year this is from or anything but it sure is nice that it came apart, now I just need to matchup the Carter #'s on the pump to a replacement.
Also, I cleaned the contacts on the sending unit and put an ohm meter on it and it behaved as it should, granted idk what the proper resistance is, but at empty it was fully resistant lessening towards full.

 

It seems to be working, then. If I remember correctly, the max ('empty') resistance should be like 85 ohms, tapering off to zero at the 'full' position.