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Car Forum / Jeep / September 2006

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1990 Jeep Wrangler Islander 4wd Question

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NewbieJeepGuy - 27 Sep 2006 03:55 GMT
I just bought a 1990 Jeep Wrangler with the 258 I6, 4wd and have a
couple of questions.  The indidivual that I got it from said the 4wd
was not currently working and when I had a friend take a look at it we
were kind of noticing that all the vacuum tubes/connections had been
removed.  Is there any complete diagrams that would show in detail the
4wd vacuum system so I can get a good list of parts and be able to set
it back up?  They also replaced the air cleaner (with a simple air
filter) and if there are some good diagrams on that I would greatly
appreciate it as well since I believe there are a couple of connections
off of there I will be needing.  I have purchased a Chilton book but it
doesn't really get into the 4wd stuff and the vacuum diagrams in there
are desciptive but still hard to read for a newbie.  Any help or
direction to a site or place that I could get the 4wd reconstruction
for dumbies would be helpful.

Thanks in advance.

D
L.W.(Bill) Hughes III - 27 Sep 2006 04:44 GMT
They sell the kit at the Stealership for around twenty:
http://www.billhughes.com/axleVacDiagram.jpg
       God Bless America, Bill O|||||||O
mailto:LWHughes3rd@aol.com http://www.billhughes.com/

> I just bought a 1990 Jeep Wrangler with the 258 I6, 4wd and have a
> couple of questions.  The indidivual that I got it from said the 4wd
[quoted text clipped - 14 lines]
>
> D
Mike Romain - 27 Sep 2006 14:47 GMT
This site might help you out some:
http://home.sprynet.com/~dale02/list.htm

The Haynes 'CJ' manual is the best one to have for your engine and it's
electrics.  That book has great detail on the 258.

If all the vacuum lines are off, then the computer will have gone into
'limp home' mode clamping down on the timing and carb mix and the engine
will run like a bag of dirt.

If you want to put it all back stock, see the link I posted above.

If you want to put the computer out of your misery it can be done by
simply adding two new wires and hooking the orange and purple wires at
the ignition module to the orange and purple at the distributor.
http://home.sprynet.com/~dale02/ignmods.htm

You then need to set the timing manually and set the carb mix up
manually.  The carb does have mix screws hidden down front that might
need a drill or saw to get at.  When setting up the mix, I believe the
stepper motor's pins should be in the middle of their travel where they
work stock to get the proper high speed running.

The computer bypass is called the 'Nutter' after the gent that posted
it.  He set his carb pins full rich.  This give lousy gas mileage and
top end performance.  You can try both.  I can adjust my carb pins from
up top with needle nose pliers or a mini screwdriver.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos:  Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)

> I just bought a 1990 Jeep Wrangler with the 258 I6, 4wd and have a
> couple of questions.  The indidivual that I got it from said the 4wd
[quoted text clipped - 14 lines]
>
> D
RoyJ - 27 Sep 2006 14:48 GMT
For a good look at all the vacumn lines for the engine, start here:
http://home.sprynet.com/~dale02/list.htm

The front axle disconnect system does not seem to be well documented.
There is a black plastic line from the driver's side of the engine to
the vac switch located on top of the transfercase. Then 3 lines going to
the vac motor on the axle. Take a look at the vac motor on the axle, see
if it still has the molded plug attached to the vac ports. With the
engine running, tranny in neutral, transfer case in 2wd, CAREFULLy reach
down to the front axle molded plug and see if you have slight vac on the
yellow line, move it to 4wd, see if you have slight vac on green line.
If no vac on either, you have a bad line going from the engine to the
transfer case. If either green or yellow and doesn't switch, bad vac
switch. If vac on one, no vac on the other, probably a bad vac harness.

A lot of folks will tell you to replace the vac system with a cable, not
a bad option. I stuck with the vac system since I switch from 2WD to 4WD
a lot.

Part numbers you may need:

vac harness (complete) 5300-2033  About $75 new at the dealer only
vac switch  5300-1101

If you post a valid e-mail address, I'll send you some diagrams.

> I just bought a 1990 Jeep Wrangler with the 258 I6, 4wd and have a
> couple of questions.  The indidivual that I got it from said the 4wd
[quoted text clipped - 14 lines]
>
> D
NewbieJeepGuy - 28 Sep 2006 02:53 GMT
Thanks Mike & RoyJ....

RoyJ if you could email some good diagrams to rmcs.david@bresnan.net I
would greatly appreciate it.  If you have a similar jeep and could take
a photo or two of your engine showing the lines in place and where they
go that would be a great help to go with them.  I have some diagrams
but being more of a visual person the actual thing would help put the
diagrams to better use as well.

THanks all for the information and if others have more to add great.

Dave
Mike Romain - 28 Sep 2006 15:12 GMT
If the computer has been disabled, you can save about 5 miles of vacuum
lines and just hook up the 'needed' items for good running....  PCV,
charcoal canister (gas tank and carb vent), EGR, distributor advance and
air filter flaps for the heat pipe for good winter running.

You can tell by looking at the plugs on the ignition module 'waaaayyyy'
down under the washer bottle on the fender.  Look at the 4 wire
connector and see if the purple wire has been hooked up.  If it has,
then the computer has been put to sleep, if the purple wire just
terminates at the plug, then the computer is still in there and it needs
a ton of vacuum switches to work right.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos:  Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)

> Thanks Mike & RoyJ....
>
[quoted text clipped - 8 lines]
>
> Dave
NewbieJeepGuy - 29 Sep 2006 02:13 GMT
Thanks again to Mike & Roy....

So a question I have then.  If i don't hook up the stock vacuum 4wd
what would be a good option that doesn't cost a lot of money to set 4wd
back up on my Jeep.  I've heard that the stock 4wd had some issues when
getting wet or cold with the snow but not sure how common those issues
are.  Knowing my luck recently I'd encounter them though.  I've also
read where some guy rigged a chain with a lever to engage the 4wd but I
don't want to do something like that because it seems a little worse
off than the vacuum idea.

I thought I had read for $200 - $300 I could get a 4wd conversion for
that jeep or something that would work out quite nicely and be better
than what it came with and very reliable.  Am I correct or just
hearing/reading crap out there?  I don't mind spending to much to get
some good reliable 4wd because I do want to do some trail rides in the
mountains of Montana here.  Other things that I know I need to get done
are the sway bar and bushings but not sure what else to look for
underneath.  The sway bar bushings (if i'm saying that right look
horrible), and I've noticed the steering wheel kind of jerk or jiggle
when driving at times, not to much give in the wheel while turning
which is nice but more jerking type stuff when going over the tiny
lines made in the road.  If that makes sense.  I've been putting a good
shopping list together and hoping to order some things next week to get
moving.  I appreciate any and all suggestions but don't have unlimited
funs for the "toy" either.  I do have a hard top so one of the items
will have to be a bestop bikini or something though when I take the
doors and hardtop off in the spring/summer for crusing around.

Thanks again all.
Dave
RoyJ - 29 Sep 2006 02:36 GMT
Most of the front axle discconect issues tend to be in the vac lines,
the plugs, and the vac switch on the transfer case. The vac motor on the
axle does go bad but not very often. The fast and dirty way to get the
front axle into locked mode is to run a vac line from most any vac port
on the engine to the center port on the axle vac motor. This will
permanently lock the axle in 4wd mode. More wear and tear but this is
the same mode as all the TJ's ('97 and up) use. Or you can spend the $$
and get the cable disconnect kit.

The steering wheel 'jerk' is worrysome. It could be that you are not
used to the Jeep suspension and it's very tight turning radius. Or it
could be loose/worn suspension parts. Sway bar bushings are not that
critical, you do need them eventually but even mushed ones still work.
Have an alignment shop take a good look at the front ball joints, tie
rod ends, etc. You also need to find and inspect all 6 'U' joints. On a
'90, they will be likely be either already replaced or shot.

> Thanks again to Mike & Roy....
>
[quoted text clipped - 27 lines]
> Thanks again all.
> Dave
L.W.(Bill) Hughes III - 29 Sep 2006 02:41 GMT
http://collinsbros.stores.yahoo.net/4x4psilok.html
http://home.earthlink.net/~stevenschreiber/cabledis.htm
http://www.bc4x4.com/tech/2002/d30shiftmotor/
http://web.archive.org/web/20030109171121/http://www.rightcoastcrawler.com/billa
Vista/D30_tech/insideD30.htm

       God Bless America, Bill O|||||||O
mailto:LWHughes3rd@aol.com http://www.billhughes.com/

> Thanks again to Mike & Roy....
>
[quoted text clipped - 27 lines]
> Thanks again all.
> Dave
NewbieJeepGuy - 29 Sep 2006 03:22 GMT
I've read up on the 4x4 Posi-Lok and to me it sounds like a better and
easier install option than fabricating with a bike chain or break cable
as talked about in the other messages.  Yes $190 compared to $20 but I
would think that the Posi-Lok system might work a bit better.  If I'm
incorrect could someone let me know?

Also if I do the Posi-Lok which bypasses the vacuum actuator system for
the 4wd could I then do the ignition mod (The Nutter Mod/Bypass) and
then yank out all the extra crap underneath the hood as Mike states?
The main quesiton I would have with that is does it affect any of my
RPM, Fuel, Temp or other gauges by doing this?

One other thing I noticed is that the person that had it the last
couple of years put a 2" lift on the body and has larger tires on the
Jeep.  So obviously the speedometer is incorrect when driving down the
road and I found out the fun way.  Going 60 MPH is what the gauge read
but the officer told me I was doing 65 (since it was a 55 he thought he
would let me know).  Is there a quick fix since I'm using larger tires
with the lift and everything and what would I need to know to buy the
correct device to get my speedometer back in tune.  Yes I know simple
things but I'm learning.

Thanks again for any help.

Dave
L.W.(Bill) Hughes III - 29 Sep 2006 03:36 GMT
Everything I can think of works better with the Nutter bypass,
including emissions, but you should make the connections look as stock
as possible so as not to fail the smog check visual:
http://home.sprynet.com/~dale02/ignmods.htm
http://www.billhughes.com/mirror/nutterbypass.htm
http://www.off-road.com/jeep/jnutter1.htm
    Speedo:
http://go.jeep-xj.info/HowtoSpeedoGears.htm
http://www.jeeptech.com/javaAps/Speedo.html
       God Bless America, Bill O|||||||O
mailto:LWHughes3rd@aol.com http://www.billhughes.com/

> I've read up on the 4x4 Posi-Lok and to me it sounds like a better and
> easier install option than fabricating with a bike chain or break cable
[quoted text clipped - 21 lines]
>
> Dave
 
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