New here with a 1988 YJ 4.2

Geos7812

Member
Joined
Aug 26, 2022
Messages
28
Location
Evergreen, CO
Hi folks. 1st post, I just signed up. I cannot wait to get digging. I am a brand new owner of a 1988 YJ 4.2L with 47000 miles. I pick her up tomorrow and will now spend the rest of this evening and morning (probably) piling through this forum.

Can’t Wait!

Geoff
 
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Hi folks. 1st post, I just signed up. I cannot wait to get digging. I am a brand new owner of a 1988 YJ 4.2L with 47000 miles. I pick her up tomorrow and will now spend the rest of this evening and morning (probably) piling through this forum.

Can’t Wait!

Geoff
Welcome
 
Hi Geoff...welcome aboard! I've got a `low mileage` YJ myself...90 4.2 with 44k...I'm curious to see your new purchase and any history...btw, that 4.2 is no joke, congrats!
 
Hi Geoff,
Welcome, I too am new to the forum.
I also just bought a 1988 4.2 but it has a little more miles, 100K+. I too will be digging for information for several issues i have with this one. One in particular is a bouncing fuel gauge, hard to tell what you have in the tank. Previous owner said if it gets to bouncing in this range, hunt a gas station....quick. I would like to be a little surer. If anyone has a fix, I would love to hear it.
 
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Hi Geoff,
Welcome, I too am new to the forum.
I also just bought a 1988 4.2 but it has a little more miles, 100K+. I too will be digging for information for several issues i have with this one. One in particular is a bouncing fuel gauge, hard to tell what you have in the tank. Previous owner said if it gets to bouncing in this range, hunt a gas station....quick. I would like to be a little surer. If anyone has a fix, I would love to hear it.
Mine has the same! I haven’t searched up answers yet, but I will start soon.
 
Evening gents...if your needle is bouncing around chances are you'll need a new sending unit...
 
Sending unit is in the tank, but on the 4.2 the fuel pump will be on the lower passenger side of the engine if it's still stock. The 4.0 fuel injection models have the pump in the tank as part of the sending unit. Just a thought, if you plan to convert to fuel injection from a carb you'd need shift fuel pumps, and could locate it in the tank at that time. ... I'm curious, what is your carb / distributor setup like on that one?
 
Sending unit is in the tank, but on the 4.2 the fuel pump will be on the lower passenger side of the engine if it's still stock. The 4.0 fuel injection models have the pump in the tank as part of the sending unit. Just a thought, if you plan to convert to fuel injection from a carb you'd need shift fuel pumps, and could locate it in the tank at that time. ... I'm curious, what is your carb / distributor setup like on that one?

I haven’t dug in just yet. I have Parts on order for a full tune up where I will jump in and understand this thing a bit more soon.
 
Thanks for the info cburyta, thinking sending unit also. My fuel pump is located on the right side of the engine, so I am assuming there is not one in the tank. Looking through the internet, seems all the sending units come with fuel pumps.
Do you have a suggestion of where to find just the sending unit, supplier, part number or any info would be great.
 
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Thanks for the info cburyta, thinking sending unit also. My fuel pump is located on the right side of the engine, so I am assuming there is not one in the tank. Looking through the internet, seems all the sending units come with fuel pumps.
Do you have a suggestion of where to find just the sending unit, supplier, part number or any info would be great.

I think this is what you'd need to look for... (search "Crown Automotive 53003341X 20 Gallon Fuel Sending Unit for 87-90 Jeep" on Quadratec if the link doesn't work)


Important note that these shipped with 14.5 gallon tanks and some with 20 gallon tanks, so watch out for that. I THINK (don't quote me) that the only physical difference is actually in the hose that goes into the tank from the fill neck ... so they could use the same tank but limit them artificially... that might be important to understand.

Also, the sending unit I thin is the same basic part with or without the pump, just the pump-less one doesn't have the pump. They look similar otherwise.

If you're interested, here's a PDF of the parts catalog, not sure how much you can get using these numbers these days, but it's a GREAT reference. I attached screen shots of the two pages that list the 14.5 and 20 gallon tank. (It was a document for a few Jeep vehicles, so pay attention to the heading of the pages to see engine time and stuff. I think I removed the non-YJ pages in this version, but there are a lot of YJ versions still.


(Not sure how long that Dropbox link will work so download it if you're interested, but should be able to view it in the browser.)

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I thought it would be a small bird nest, but it was Eagles 2 story house, just won't it to run. Computer is dead got lot dead end wires and wires with multiple color with duct tape around them, wires go to plug in which don't plug into anything. So, what I need in a wire harness for the basic engine heat gage, heater, alternator, starter, distributor, brake sincere and choke. Or can I just cut that wire that don't go any place and shoot the guy with duct tape and multiple color splice wire lol. :unsure:
 
Hi and welcome. I bought a 1988 YJ in July and started digging in about a month ago due to a backfire from nowhere starting up. Great forum with really helpful folks all over the place. Anyway I too had a bouncing gauge and I toom the dash off, took the gauge cluster out, took the gauges off, took the flimsy PCB off and cleaned it up with soft wire wool and all the connectors with a gentle wire toothbrush. Then cleaned up the back of each gauge the same. Got everything shining. Then fitted a new fuel gauge and temp gauge and put it all together again. Then took the earth of the firewall and took that to base metal as well as the wire, then screwed it back on. No bounce! Solved it. Even at low fuel, no bounce. Hope that helps and even if its something else you've learned how to dismantle and clean up your binnacle and gauges! Good luck.

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