Fuel Sending Unit ??

I have an 89 with a bad fuel sending unit, how far up in years can I go for a direct swap? I found a "parting out" 99 cherokee, would that sending unit work? Or how about the tank too??

Thanks
Kenny
Vancouver, Wa.

You should be able to use up to a '90 - with the same size fuel tank and engine.

99 will not fit, I guarantee it. You can swap the tank in, but expect to need to do the following as well:
* swap fuel filler and vent tubes
-- possibly swap filler neck as well
* swap fuel rail and injectors, may not line up with older manifold
* swap fuel lines
* add a 97-up fuel tank heat shield to keep the exhaust from melting the tank or boiling the gas

You could probably get away without swapping the fuel rail and injectors but I'm not sure, might have to do a custom setup for the fuel pressure regulator up there.

EDIT: oh, and your gas gauge will either go backwards or not work at all. You'll need to do custom electrical work (a little splicing) to make the pump work with the older XJ.

Cool, I can understand the filler neck not lineing up. But I dont get the filter or fuel rail. All I need is really the sending unit, the tank would have been a extra. But what does that have to do with the rail & injectors?

Fair question - the 96 and later senders are set up for a single fuel line, i.e. the fuel pressure regulator is inside the tank, and there is no return line from the fuel rail. Your 89 has the fuel pressure regulator on the rail and a return line that dumps extra fuel back into the tank. Unless you feel like modifying that setup to work with the sender containing the fuel pressure regulator, you'd have to swap it all over.

That is, if you're talking about the whole sender assembly including the fuel level sender and mounting bracket - if you just want to swap the pump itself over, I think it might fit but I'm not sure.

Ok that makes a ton more sense. Nope all I really need is the sending unit (for the gas gauge) But ok that was correct. Nope I dont wan to modify anymore than I have to. I found a 93 parting out so maybe I will try that one.

A 93 may go backwards too... My 91 mj gauge goes backwards with an 88 mj sender. You probably want 90 or earlier. Sorry about the bad news

(Or just stick a label under the gauge to remind you that full means empty)

yup- it's gonna read backwards-- you could just fill it 'til it's empty and run it 'til it's full... but I don't think "full" would correlate to "empty" from one unit to the other and vice verse.

It *mostly* does on my MJ. Full means empty, and empty means full. It's nowhere near linear in between though - half-tank is about 1/8 from "full" (i.e. empty) and by the time you get to half-tank on the display you can basically watch it drop as you drive down the highway.

I did find a brand new set up, sender, pump all ready to drop in for $125. Not to bad a price I guess. Simple drop in set up. Might be the best way to go.

My main notebook is currently deadlined, but I didn't think the change in the direction of the gauge/sending unit happened with the change from Renix to HO/OBDI.

For the Renix ZERO ohms = empty, 44 ohms = 1/2, and 88 ohms = full. At some point that was essentially reversed, I don't have the numbers handy but someone can post them up from the FSM for later years.

EDIT: and Kastein is right on the MJ, totally different from the XJ, I know because he schooled me on the differences.