Fuel pump not working so I ran it directly to battery and the positive just sparks and gets really hot. I disconnected the thick connector from the negative battery terminal and connected the fuel pump ground by itself and it started running! I disconnected the hot wire from the fuel pump and it still runs with just the gauge wire and ground. I have no clue what that means! With everything connected it won't run.

 

so with only a single wire connected to the pump, a ground only, it runs??

 

A motor needs power and ground to work. Do you have a wiring schematic for the fuel pump circuit? Are you sure you are not mixing up the wirecolors?

 

Is this the Jeep you're talking about?

https://www.cherokeeforum.com/f2/cal...rokees-195438/

 

He's going to end up burning this thing to the ground. Or blow it up. Or both.

 

Yup

 

I will burn it down trying!!! The thick positive is still connected but nothing other than pump ground to the negative. I ran the gauge wire from the pump directly to the cluster

 

OK, thanks to Ken we can guess maybe it's an 86, 2.5? It's fuel injected? If you have a row of four relays on the right inner fender, the second one back is probably the fuel pump relay. I think it's the 87 socket that provides power straight to the pump. If I'm right you should fine continuity between that socket and the power wire at the pump.

There are diagrams in my signature as well as a link to a nice set of (4.0) engine bay pics.

 

How do I find or test continuity. With the pump hooked up I tried jumping the connectors with the fuse out and all it does is clicks. Yes it is a 1986 2.5. I have replaced the relays as well. The middle part where the relays goes (87A) has no wire underneath going to it. It just sits in an empty socket

 

It's OK 87A is empty. The DPDT relay, (single pole, double throw), would put power to that (from 30), at rest. When the ign powers up 86, and 85 is grounded, (by the puter I guess), it then shoots power from 30 to 87 out to the pump.

There's lots of ways to see if a wire is connected, (going through). A meter set on ohms will not only tell you if its connected, but how well. Or a test light, or sometimes I'll power one end and just quickly brush the other on a ground and look/listen for a spark.

In your shoes I might use an old vacuum cleaner cord or some other long piece of wire. Connect it to the one that provides power to the pump, then find the other end...hopefully at 87.

You DO have a row of 4 relays, and it IS fuel injected, correct?

You really should find a meter...the $5 Harbor Freight Digital meter actually works OK, at least for a while. You will find plenty of other uses for that on your Jeep! Or a cheap test light, (continuity tester) the kind with a battery will work.

 

Yes I have an ohm meter. So I would connect red to 30 and black to? And what should the reading be?

Why would the pumps hot spark when touching the positive battery post when it was all connected?

 

Because the pump draws current when it starts.

 

One lead in 87 and, the other on the Positive power wire at the pump. That would be to verify that that wire is there and working like it should. I'd expect less than a few ohms. If that is correct, and the pump is properly grounded it should run when socket 87 gets juice. For the third time...do you have 4 relays in a row on the right inner fender, and is it fuel injected?

PETE! Where are you?

 

Yes I do have 4 in a row and it is fuel injected

 

OK! Interesting...I'd gathered Renix started in 87. You probably have a C-101 connector there by the brake booster. I strongly recommend you take a look at Cruiser's tips, (found in My signature, and his). It's my bet you should do 1 through 5.

Yep, that 87, (fender side), is indeed the power to your pump. It looks like they made it interesting. The gauge wire is Violet, and the pump power Pink/Tan stripe. Might be easy to mix up! If the pump indeed DOES run powering the Violet wire, (I'M not saying to do that! Might blow up!), I'd pull the pump and look for the shorting/mis routed wires.

If it doesn't run when you juice the power wire you should just stop, disconnect the battery and change the pump, or have it changed.