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Help an XJ newbie... 93 with fuel problems

D

dodgethis12

NAXJA Forum User
Location
Virginia
Looking at buying an XJ. Its a red 93 4.0 auto 128K. Its the plain model with rollup windows, black grill, steel wheels with black center caps.. etc

Is this a 4.0 HO or non HO? also what is the typical gear ratio?

The jeep is very clean inside and has low mileage for the year. I think I can pick it up sub 1000 dollar range.

Here is the problem:

When the jeep starts it immediately begins to smoke.... gray smoke, not blue oil smoke. The exhuast reaks of gas fumes like its running supper rich. The engine has a miss or stumble to it. Its more than just a bad plug... its just fogging gray fuel smoke. When you pop the hood you can smell gas....

Previous owner was driving until it started missing/stumbing and parked it about 2 months ago.

Is this a common problem? Injectors? Regulator? I have some mechanical experience however, I have not ever messed with a 4.0. Please give me your thoughts.
 
93 will be an HO I believe, unless someone swapped the motor.

a stock 4.0 auto is going to have 3.55 gears unless it had the towing package, in which case it might have 3.07 (not sure, others will know way more than me on that.)
 
The jeep doesnt have the towing package Im aware of... theres no receiver on it or any signs of a tow hitch factory or home made.... which is good because I know no one has ever towed with it.

Im just wondering if this massive rich fuel problem and smell of gas is an easy common fix or if the problems may run deeper....

if you can guys PLEASE HELP ASAP!!!

Im going to look at it again tonite. Please let me know what I need to look for. Im pretty mechanically inclined, just a 4.0 newbie!

Thanks
 
Only thing I can think of is to check your O2 sensors, but that much of a gas smell may indicate leaky injectors or a broken fuel rail or something. I haven't done much with the fuel system other than replacing some lines and my gas tank... best bet is to wait for one of the resident pros to show up (I'd bet on joe_peters, Tim_MN, ehall, 5-90, et al at least knowing what to ask, I don't that's for sure!)
 
On any vehicle that doesn't run right, insist on doing a compression check. That will at least tell you if the rings and valves are OK. The other stuff, you can always fix without much cost.
 
winterbeater said:
On any vehicle that doesn't run right, insist on doing a compression check. That will at least tell you if the rings and valves are OK. The other stuff, you can always fix without much cost.
Click to expand...

Winterbeater is exactly right, do a compression check, and that will give you a chance to examine the spark plugs while you are at it.

As noted before, it is an HO motor (91+) unless it has been swapped with an earlier motor.

Super rich--fuel pressure regulator bad, fuel pressure s/b 30 w/vacuum to the regulator, 39 psi w/out vacuum. o2 sensor bad, an exhaust leak upstream of the o2 sensor, bad coolant temperature sensor, a bad synch sensor for the injector timing (in the distributor), bad injector(s). You could be getting a fuel smell under the hood from leaking fuel rail disconnects or if you have the older style two-piece injector bodies, they tend to separate and start leaking where pressed together and are a serious fire hazard as they tend to puke fuel onto the exhaust manifold.
 
The jeep smells like raw gas as the tailpipe and there is a strong underhood gas smell as well. It has 128K on it. Im picking it up in a few days...

How prone are the ex. manifolds to cracking.... it sounds to me like I has aleak somewhere underneath.

ALso its smoking around the intake where it meets the block when its running. Cant tell if its just the valve cover gasket leaking. I can see any visible sign of naked gas running out of the injectors.
 
Let us know when you have it.

First, did you do a compression check? If you did, what did the plugs look like?

Second, I would put a fuel pressure gauge on it. If you don't own one, most chain parts stores rent them.
 
I meant to say I cant see any gas running out...

I didnt compression test it.... I havent had time and the guy doesnt have time to meet me for me to take the jeep apart before I buy it. I got it for .... well lets say... cheap!!

I plan on doing full tune up... all fluids, filters, plugs, wires, etc...

Im really hoping this is an external issue I can take care of easily.
 
dodgethis12 said:
I meant to say I cant see any gas running out...

I didnt compression test it.... I havent had time and the guy doesnt have time to meet me for me to take the jeep apart before I buy it. I got it for .... well lets say... cheap!!

I plan on doing full tune up... all fluids, filters, plugs, wires, etc...

Im really hoping this is an external issue I can take care of easily.
Click to expand...

Well, my .02 worth is this: you have bought it (and cheap is good), so now do the compression test. This will allow you to see the condition of the sparkplugs, and they will tell you a lot, including if you need new plugs.

There are so many things that can lead to over-rich and fuel smell you should not start throwing parts at it--way too expensive. Test, inspect, and R&R only those items requiring it.
 
Are there 1 or 2 coolant sensors on this engine? I know some vehicles use 1 for the guage and 1 for the computer.

Also what trans fluid should I use? ATF+4?


I have seen about people opening up the gap in the plugs to like 70 from 30-35... whats this do?

I think I do have the 2 piece injectors... theres like little metal clips int he body of the injector about halfway up...

Could MAP and IAT sensors be responsible?

I know its just a guess until I get it, but I just want to cover all the possibilities and learn a little more about it so I am ready to go when I bring it home. It needs a good polishing, and a headliener... but my time is free so I'll probably do it myself.

I would also like to have a better set of wheels and a tow hitch for the rear if anybody close by has some for sale??
 
trans fluid - dexron/mercon.

I'm not going to answer the other questions as I don't feel I know enough to be sure I'm right, but I wouldn't be surprised if you have an answer within minutes (betting Joe knows!)

Headliner is fairly easy - the toughest part of the trim to remove is the A/B pillars, especially the A pillars. You can probably get away with not actually removing them all the way though, so they won't be as frustrating as they could be. You'll want a large Torx driver (I think it's T50 or T60, not sure? The whole T8 to Tginormous set is $15 at Home Depot) for removing the seat belt brackets from the pillars/frame so you can get the trim off to put the new headliner in, aside from that all that is needed is a phillips screwdriver and your hands + patience. You may want a helper to make sure you don't fold or crease it though. You can probably pick one up for under 20 bucks out of a cash 4 clunkers vehicle in a local junkyard.
 
dodgethis12 said:
Are there 1 or 2 coolant sensors on this engine? I know some vehicles use 1 for the guage and 1 for the computer.

Also what trans fluid should I use? ATF+4?


I have seen about people opening up the gap in the plugs to like 70 from 30-35... whats this do?

I think I do have the 2 piece injectors... theres like little metal clips int he body of the injector about halfway up...

Could MAP and IAT sensors be responsible?

I know its just a guess until I get it, but I just want to cover all the possibilities and learn a little more about it so I am ready to go when I bring it home. It needs a good polishing, and a headliener... but my time is free so I'll probably do it myself.

I would also like to have a better set of wheels and a tow hitch for the rear if anybody close by has some for sale??
Click to expand...

You are right about the coolant temp. sensor on the thermostathousing.
There is also a Manifold Air Temp sensor!
The sensor for the temp.gauge is nearby the firewall.
Don't use ATF, but Dexron II or III.
Check the vacuumline of the MAP.
And do the tests of Joe and Winterbeater.

wim
 
You can always pick up a set of Ford orange-top 19 lb injectors at the salvage yard for about $30. Direct fit replacement, work great.
 
dodgethis12 said:
Are there 1 or 2 coolant sensors on this engine? I know some vehicles use 1 for the guage and 1 for the computer.
Click to expand...
Assuming the 93 in the subject line, it has 2 temp probes--the one in the tstat housing is for the computer and there is another single-wire probe at the back of the head near the ground strap that drives the gauge

Also what trans fluid should I use? ATF+4?
Click to expand...
Dexron VI is the current rev of the specified fluid

I have seen about people opening up the gap in the plugs to like 70 from 30-35... whats this do?
Click to expand...
in theory it allows for fuller, cleaner combustion, however the XJ tends to miss a bit at stock gap and opening it up is going to make it miss even more

I think I do have the 2 piece injectors... theres like little metal clips int he body of the injector about halfway up...
Click to expand...
the metal clip holds the injector to the rail. you have 1-piece injectors

Could MAP and IAT sensors be responsible?
Click to expand...
IAC won't do that since it only controls airflow in response to computer commands, and does not tell the computer to richen the mix. There are MAP and MAT sensors that tell the computer how much air is in the manifold (pressure and temperature yield density). Also the coolant sensor could have the same effect. If it were me I would disconnect those one at a time and see if anything changed. Another option would be to bring replacements for all of them and a 3/4" socket to change the coolant and MAT sensors.

Also look for leaking injectors and disconnect the one that is puking if you find it.
 
Thanks guys you really know your stuff. It makes me more confident to buy this knowing I can pretty much do all the work on it myself and having this site deffinately makes that alot easier.

When Im at the Jy.... What vehicles should I be looking for to grab the orange 19# injectors from? Will these be in the 5.0 trucks, explorer's? Anything I should look for or stay away from? Any indication as to how to tell which injectors are right upon arriving at a suspect vehicle?

Also.. the a pillar trim... how do I get it down without snapping it. Im sure its brittle being a 93.

Thanks
 
Be *really* careful on the trim. You can use a small flat blade screwdriver to remove the two trim caps, then pull the screws under them. You'll need a smallish Torx (T15 or T20, forget which, this is why I suggest buying the torx set at home depot! Jeeps are covered in the darn things) to get the screws out of the handhold ends on the passenger side. Once that's done, just sorta pull it away from the frame carefully, starting at the B pillar or top of A pillar. Leave the part behind the dashboard back there, just sorta let them hang down slightly. This is something I would practice at the junkyard when getting the headliner - if you can't do it without breaking the trim, try again. You'll need to remove the dome lights (they use push nuts, can be removed carefully with needlenose pliers, reflattened, and reused) and sun visors (phillips screwdriver) as well. Also, if you can find one, this is an excellent time to get and install an overhead console if you want to - the wiring harness goes behind the headliner.
 
The Ford orange-tops were used in 3.8 L and up Fords, including the E350 vans.

They can also be had on eBay for a reasonable price, but then you have shipping. When you do a search on eBay you get the best results search "mustang injectors". Lots of different pressures, make sure you stick with the 19 lb ones.
 
Im not at all familiar with fords... but will the injectors be an actual orange in color? Can I use new factory XJ o ring kit to seal them?

what year range of vehicles will i be looking for? If I get orange injectors from a v8 ford will they necessarily be 19 # ?

Sorry for all the questions, but the nearest u pull is quite a ways away so I wanna make sure I grab the right ones the first time.....

recommendations on plug gap?

What kind of mileage can I expect from a stock 93 XJ with 235/75 street tires that is *Running correctly* and well tuned up?

Thanks
 
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