20 Most Recent 1990 Jeep Wrangler Questions & Answers


Are these your wire colors for headlamps? In the diagram, the top wires are voltage, the bottom wire is ground, check both. There is no fuse for headlamps. There is internal circuit breaker in headlamp switch. The exterior lamps not including headlamps are fuse protected.
Maybe a problem with bulb or wiring circuit. The voltage for hi beams on both sides, come from the same place. Lo beams, the samething.

1990 Jeep... | Answered on Apr 06, 2018

probably not but adjusting the amount of pinion movement before the solenoid makes contact to spin the armature would fix the fault

1990 Jeep... | Answered on Feb 24, 2018

Could be several things. Does the rear drive shaft have any play in it? If so, could be that the spider gears, ring gear, or pinion gear or bearing have disintegrated. If it was the pinion or ring, it will cost several hundred dollars for the new ring gear and setup. It is not a part you will be able to install yourself.

1990 Jeep... | Answered on Feb 18, 2018

Not sure I remember this correctly, but with older cars that have carburetors, fuel is feed into carb via suction. Maybe you have a failing vakuum pump that's suppose to deliver the suction. If possibly have your error codes read via the OBD portal of your car, you can do this yourself if you have a OBD scanner or have a shop do it for you, shouldn't cost more than 100 bucks to have them scan the ECU or any error codes logged on the ECU. (Engine Control Unit)

1990 Jeep... | Answered on Dec 06, 2017

No rear light's at all could be a bad ground connection . Looking at a wiring diagram to check what all is involved in the rear lighting circuit's should be the first step .or you could just look under the rear of the vehicle for corroded wiring ,loose connection on the frame or body etc... Sometimes just having a good look around reveals the problem . If nothing is evident ,testing with a DMM - digital multi-meter will need to be done . Using a testing method called voltage drop . It's so simple ! Watch this two guy's , professional technician's , teachers etc...
Mastering Voltage Drop Testing with Pete Meier and Jerry Truglia
Free wiring diagrams here http://www.bbbind.com/free_tsb.html
Enter vehicle info. Year , make , model an engine size. Under system click on lighting ,then under subsystem click on stop lamps .Click the search button then the blue link .Don't know if you'll be able to make head's or tail's out of these diagram's . You may want to go to ALLDATA an pay for a year OE Info for Student and DIY er Vehicle repair information you had no idea existed

1990 Jeep... | Answered on Nov 17, 2017

not sure if this link will help you out but have a look and see if you can find anything of use to you.
1990 Jeep Wrangler grind and grind will will not start Google Search

1990 Jeep... | Answered on Nov 03, 2017

Look from side on , easy to spot which pulley is out of alignment. Look at bottom pulley too, crank/balancer can sometimes be the problem.

1990 Jeep... | Answered on Aug 23, 2017

must be 4.2L engine the 2.5 is EFI TBI.(French EFI)
the 4.2 has computer controlled carb from H3LL
never ever buy a jeep like this, ever.
if hellbent on this bad car, to fix then buy the service manuals off fleabay.. (id not even hesitate there)

my guess is the carb is bad, what checks matters are.
fuel nozzles dead, is that.
1: fuel pressure at spec. not dribble tests. (no dribble yes, means pump dead) (using a real pressure gauge)
2: float level correct. ? if bowl dry bingo. !
3: jets not clogged, inside carb.
4; carb computer working (Tests stated in SM)
5: dead carb solenoids.

there is no worse car than a ECM controlled carb. horrid system.
ended in 91. as Chrysler took over..from AMC

join a real jeep forum and hear them moan, ?

2 fuses need to be good, F1 and F2, 1amp rated.
in the diode fuse assembly.
or the idle solenoid goes dead.

1990 Jeep... | Answered on Mar 14, 2017

thrown parts never fixes cars. 50 causes, can be 49 time guesing wrong or worse added a new defective part to the mix.
yes finish the tune up, why did you do it last>? odd no?
vacuum leaks cause, high idle on all jeeps!!
and then the ECU sees bad idle and tries over and over to reach
700rpm (spec) and cant so hunts it (that hunting today is deemed ******* , ask toyota why , fines)
all vacuum leaks do that , if it sucks AIR , illegally it will do that.
illegalll means air not from the ISC stepper drive device.
bad hoses, bad gaskets what ever.

does engine reach and hold 180f coolant temperatures???
this is first. it must, does it?
ill not guess, I propose doing a thing called TESTING.
lots of thoughts, really .... here are mine, plus RENIX facts.
I owed 2 , 1988s, with dang REnix french EFI? a horrid system.
TBI is yours TBI not MPI? (count the injectors there) mpi is 4.
no sold scan tools work on it and no CEL lamp. on RENIX.
nor does the key on 3 times trick. work before 91, dang!
1991 it changed to far better and the 3 key trick works then...

black smoke is: (rich)
high fuel pressure. (id be all over this)
injector leaks, (do a leak down test )
ECT bad, e (old name CTS)
on a hot engine, it reads (ohmmeter tests)
25,000 ohms is wrong, for 0degr. F.
317 ohms is about par for 180f normal temp , is yours 300 hot unplugged??????. a simple 5 min test.
if not the thermostat is bad or CTS bad. (IR gun it to learn this)

i see that rough idle , its MISFIRING and its really flooding .
and black smoke is always results of that, and most CATcons this old are now dead, (cat converter on all mine broke-up to bits and gone inside, and stinks any time it's rich or misfiring) par for 90s./:

the 1990 wangler books are rare, but can be found on ebay
buy one is my best advice,

its and old jeep
and its best to check compression on all old cars.
did you? x5 warm or hot, and WOT tested, (throttle open)

the 2.5L most 1990(not 91)
have TBI and ****** RENIX EFI (French junk)
only jeep dealer scan tools work here, not you.

the injector must not leak. just 1 injector here,
(key off running does it dribble now? must not) looking with eyes./
(the SM is in my hands) service manual..
2.5L (NOT 4.2L)
conducted a tune-up last
cap,rotor, wires, sparks and filters is a full tuneup on any neglected 90s jeep.
good engine first
good spark
then fueling last.
order matters, on old cars,
new cps.
yes all injectors tick but yours has only 1.
and takes a stethoscope to hear. (or my mag sensor tool)

this AMC spark system uses and ICM 2.5L only
and 50 tooth CMP sensors in the Distributor. (CPS you called it?)

my guess you replaced the TDC sensor
TDC sensor (mounted at the rear of the engine on the flywheel housing) CKP its called today. (yes names all changed long ago)

in a real shop we sCOPE the spark to see if its ok.
then check
Fuel pressure, the EFI in this car can not correct bad fuel pressure
its blind to it.
this engine has a very odd TBI
it has a pressure test port
and a FPR pressure adjustment screw.

here are the SM words on this, and I quote.
Fuel pump operating pressure is 14.5 psi (100 kPa). The fuel pressure regulator is adjustable by means of a Torx® head screw on the bottom of the pressure regulator.
  1. Remove the air cleaner assembly. Remove the screw test port plug on the throttle body, then install a fuel pressure test fitting. Pressure test fittings are available at many auto parts stores.
  2. Connect an accurate pressure test gauge to the test fitting.
  3. Connect a tachometer to diagnostic connector terminals D1-1 and D1-3, then start the engine and accelerate it to 2000 rpm.
  4. Read the fuel pressure on the gauge. If necessary, turn the adjustment screw on the bottom of the fuel pressure regulator to obtain 14.5 psi (100 kPa) of fuel pressure. Turning the screw inward increases the pressure and turning the screw outward decreases the pressure.
  5. Once all adjustments are complete, install a lead seal ball to cover the regulator adjusting screw. Turn the ignition OFF, then disconnect the tachometer and remove the fuel pressure gauge. Install the original plug screw into the throttle body, then install the air cleaner assembly.

top is test port
bottom is adj screw. (this is like 1st test on rich fuel)

1: cyl compression at spec, WOT.
2: a real tuneup completed ,not just spark plugs. (ICM bad?)
3: ECT reads 300 ohms hot (CTS)
4: fuel pressure at spec. 14.5psi.
5: injector not leaking. (had bad fuel in the last year, or now?)
6: there are no sold scan tools work here, so id have to scope
all ecu pins to find cause. sorry but its sticking RENIX.

has the car sat unused for a year, ? no history
when was car a good daily driver, ? last decade? last week?

1990 Jeep... | Answered on Mar 14, 2017

most light switches only need the plastic around the steering column removed to replace the switch

1990 Jeep... | Answered on Jan 05, 2017

Check if the fuel pump is well positioned, if so then remove the fuel host after the fuel pump to see if the fuel will come up.

1990 Jeep... | Answered on Jul 17, 2016

http://www.wranglerforum.com/f218/vacum-diagram-90-yj-with-4-2-a-89703.html page 5

1990 Jeep... | Answered on May 05, 2016

remove cluster,
remove lamps
replace with new
ask any mechanic in town, its not something , super hard.

1990 Jeep... | Answered on Jan 02, 2016

you need to use the correct injector for your application as for the no start problem you have now pull the plugs and make sure they are clean and not flooded out from excessive fuel, also make sure the oil in the crankcase has not been contaminated with fuel

1990 Jeep... | Answered on Oct 31, 2015

if the dash light dimmer is not working you may need to find out why,if you just want brighter lights then look at whats available in LED replacement bulbs

1990 Jeep... | Answered on Apr 03, 2015

do a 60k tune up first, all below assumes you did, spark parts, filters. dah?
first off the engine EFI runs a map sensor, (called speed density system)
so that means if the engine can pump air (compression tests PASS)

the MAP see that, air flow (calcs) and matches air with proper fuel.
1990 is a vary bad year, it has the horrid, Renix french pos EFI system. (owned 2, can taLK days on this ecu FROM H3LL)

but there is no CEL lamp, nor any scan tool , that will work here.
(unless you can find a working DRB tool, ) NO FLASH CODES !!!
above poster never seen RENIX, so.. .answers wrong. ITS OK.
1993 this changed (Chrysler) and started OBD1 ECU which we can scan easy. (innova 3140)

all this means is you must be smarter than the average bear.
are you>? got tools, meters. and all that? you will need it.
and a FSM book or login to alldata.com like we do.

if compression test pass, and vacuum at 19" idle and gunned throttle drops low fast and if you release throttle it goes why high fast 25inches>? and goes to 19inchs again, the engine is ok and cat not melted, all that in 5min work (vacuum tests) and vacuum not bouncing? 1 glance, no its steady vavcuum.
so I wave my magic wand, go, gee engine is ok.
i then check fuel pressure use a REAL gage.
it idle and throttle gunned. for spec pressures.

if all that pans out> whats next? well EFI is next,.
i check the MAP sensor voltage at 3 points.
key on, idle and gunned. for spec, readings. if not map is bad. or just clogged.
check all the other sensor by hand is next. and ill not attempt do post what ever mech ,knows here, "basics"
a volt meter , you can check them, ECT, IAT, etc.

my wild guess low fuel pressure. (BASE ON OK 1 MILE)
or FPR stuck wide open' (bad fuel pump reg)
or a bad wire to fuel pump, such that pump does not receive full 12vdc power.

here is map readings, ill post this because many books fail to show it.

if input to map is good, but output wrong, the map is DOA.

1990 Jeep... | Answered on Mar 10, 2015

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