Fuel pump assembly

[Thepepenator]

The floter on my 92 mj went out, and i do not like the idea of driving around not knowing how much gas i have. I looked on ebay, and saw one in my local autozone; I called them and they informed me that the one they had was for a 1993 xj.  To me, they look the same. now, my question is, will it actually work?  I have read some posts saying it will, then some other people say it will not work at all. I don't want to spend $80+ to buy something that will simply not work. 

[gogmorgo]

Trip meter? All of my fuel gauges work, but I have zero confidence in any of them. Especially in the MJ since the $#!&ty fuel pump I put in while I was at the side of the road didn't fit properly, and pulls fuel from the middle of the tank somewhere.

 

There was a post not long ago about very carefully taking working guts out of an XJ sending unit and sticking them into the MJ's. Might want to give that a look before committing.

[Newton]

You won't find a replacement mj sending unit in stores best bet is pull-a-part no mj's at the junkyard where i live so i hacked up that fuel sending unit from autozone and adapted it to the mj one and i get close to accurate readings on my fuel gauge.. its not 100% accurate but i would say at least 98% that catch is that it reads in reverse due to different polarity between mj and xj but i got use to reading it backwards...E-everythings ok F- find nearest gas station :yes:

[DirtyComanche]

You won't find a replacement mj sending unit in stores best bet is pull-a-part no mj's at the junkyard where i live so i hacked up that fuel sending unit from autozone and adapted it to the mj one and i get close to accurate readings on my fuel gauge.. its not 100% accurate but i would say at least 98% that catch is that it reads in reverse due to different polarity between mj and xj but i got use to reading it backwards...E-everythings ok F- find nearest gas station :yes:

 

The difference in polarity is NOT a MJ vs XJ thing.  It's a Renix vs HO thing.

[Newton]

 

You won't find a replacement mj sending unit in stores best bet is pull-a-part no mj's at the junkyard where i live so i hacked up that fuel sending unit from autozone and adapted it to the mj one and i get close to accurate readings on my fuel gauge.. its not 100% accurate but i would say at least 98% that catch is that it reads in reverse due to different polarity between mj and xj but i got use to reading it backwards...E-everythings ok F- find nearest gas station :yes:

 

The difference in polarity is NOT a MJ vs XJ thing.  It's a Renix vs HO thing.

 

 

Oh i see...so a renix era xj fuel pump would work with a mj?

[gogmorgo]

Fuel pump, yes. A Renix XJ and Renix MJ use the same fuel pump. I don't know if an HO fuel pump is the same.

The sending units are mirror images of each other. HO and Renix are physically compatible (I.e they fit) but the fuel guage will read backwards.

[johnj92131]

Here is the link to the 91 Fuel Float repair.  Excellent documentation and pictures:

 

http://comancheclub.com/topic/52339-fuel-sending-unit-repair/

 

To the O.P. - Read that thread before you buy anything.

[Thepepenator]

Fuel pump, yes. A Renix XJ and Renix MJ use the same fuel pump. I don't know if an HO fuel pump is the same.

The sending units are mirror images of each other. HO and Renix are physically compatible (I.e they fit) but the fuel guage will read backwards.

So in other words, since they are both renix it will work?

[gogmorgo]

If you're only talking about the fuel pump, yes.

If you're talking about the whole sending unit, the float arm, etc, there are physical differences in the unit itself. Members have made them work, but it's not a simple drop-in affair, if that's what you're asking.

[johnj92131]

The floter on my 92 mj went out, and i do not like the idea of driving around not knowing how much gas i have. I looked on ebay, and saw one in my local autozone; I called them and they informed me that the one they had was for a 1993 xj.  To me, they look the same. now, my question is, will it actually work?  I have read some posts saying it will, then some other people say it will not work at all. I don't want to spend $80+ to buy something that will simply not work. 

 

Thepepenator,

 

People are talking about 2 different things in this thread.  Your first sentence above seems to indicate your fuel gauge is not working properly because of a "bad float".  Meaning the fuel level signal is not getting to your fuel gauge

 

1)  If you don't know how much fuel you have in your tank - A new fuel pump will not fix your fuel gauge problem.

 

2)  If your fuel pump is bad, your truck will not run.

 

 

For problem #1 there is NO new part your can buy to fix the problem.  The factory parts are no longer available.  So DO NOT throw away your current "floater" assembly.  It can likely be fixed/repaired.   See the link in post #7 above for a how to.

The "floater" in the Comanche is NOT the same as the one in the Cherokee.  Because the shape of the fuel tanks are different between the Comanche and the Cherokee.

The Renix era Comanche "floater" will fit in the H.O. era Comanche fuel tank correctly BUT it will read FULL when the tank is empty and will read EMPTY when the tank is full.

 

Hope this helps.