Ok so I put a new pump and sending unit in and my gauge is backwards when im empty it reads full and when I know Im full it reads empty. So my question is could it just be the neg and pos wires are backwards? Sounds right in theory but I just wanted to ask you guys first just to see if anyone has had this problem and how they fixed it. Thanks

 

if the sending unit is the same exact as the last one then it is a good chance that is the problem. Should always test the pump and guage before you lock them back in.

 

x2

 

yeah an 89 and i put in a pump from a 91 and its reading backwards to i figur i could just take out the the gauge and switch the wires there but it's different than me and my brother thought oh well at least my jeep is even more unique

 

Well I got the new one from a guy I bought my 88 from and he got a new one and I went and got it from him. Is there a difference between the 88 and the 91 pump and sending unit. I know there is differences in the trucks but Im not sure of the pump. I did test it just to make sure it worked but I didnt think to check the sending unit. lol O well you live and learn right. lol

 

Yep the sending units are different from an 88 to 91. The thing to always remeber is when chrysler took over in 91 they made sure almost all controls that effect the powertrain were changed.

 

Do you know what the difference is? Does it pump the same amount of fuel?

 

The pump is the same... The sending unit is the difference. There is a bit of difference in the range of them.. but it is pretty close.