1991 Jeep Wrangler - Page 9 - Answered Questions & Fixed issues

Check your alternator and charging system

1991 Jeep... | Answered on Jan 05, 2010 | 256 views

Yes there is a PCV valve, you just have to look for it.
Engine may be over full on oil.

1991 Jeep... | Answered on Jan 04, 2010 | 391 views

check the wiring at the starter for good connection if good replace starter, have it tested at your local parts house, they will uaually do this for no charge

1991 Jeep... | Answered on Jan 03, 2010 | 107 views

New Axle grease on the sliding link gear? Change the gear oil in your front differential, and, make sure the vacuum line is the correct I.D. If it is too large (it doesn't take but 1mm or 2mm - 3/16" or 7/32"?) and the vacuum is just a little too weak. also, is the vacuum modulator on the axle NEW? If so, are all connections tight, as short of line as possible, and as few diverters as possible. This is an area where very few things can go wrong because there is nothing to it. Brand New Line and connectors "IF" you have changed ANY at all. any stight kinks or cracks in the line, anywhere, and that's enough to throw off any attempt to "Shift-On-The-Fly", right... Check the easiest, most unsuspecting areas... also, if you don't have 'Locking Hubs' or "Lock-Outs", get a set of WARN lock-outs on the front. They are fairly cheap, but Quality Manufactured. Not a lot of moving parts, easy to maintain (keep 'em well greased with bearing grease, esp. after a weekend of Dirt, Water, Rocks, or any 4X4ing...) and install-remove-reinstall. Do this maint. at least 4x's a yr. No Matter What- and take your time, do not over-tighten, either. tighten the allen-head screws like you do head gaskets or a tire. Trust me, a $75 pair of WARN's will last you for the life of the Jeep. Vacuum issue should be easier than the lock-outs, and they are easy. One more thing about the lock-outs, you have them on there to reduce wear on the front axle, axle u-joints, driveline and transfercase. I wish I had a Scrambler.... Don't you? Dumb question, 'aye?????

1991 Jeep... | Answered on Jan 03, 2010 | 200 views

Yes it is vacuum engaged. Check the vacuum motor and last but not least there is a shift fork that it engages to lock your front axle. Sometimes the shift fork gets bent and will not allow engagement. Also check the rubber vacuum line that runs to the engagement motor.

1991 Jeep... | Answered on Dec 08, 2009 | 173 views

There is an idler pulley close to the power steering. Loosen the bolt that goes through the front of the idler pulley first. Then you will see the head of a bolt looking up at you. Turn the bolt clockwise to tighten and counterclockwise to loosen. The pulley is attached to the threaded bolt and it moves the pulley up or down as needed to adjust the belt tension. When the belt is replaced turn the bolt until the belt is tight. Remember to check the belt again after a few hundred miles. A new belt will stretch and loosen.

1991 Jeep... | Answered on Dec 08, 2009 | 475 views

Sounds like the trans needs to be rebuilt as it's been abused. The clutch may be dragging during shifts and not completly disingaging or a lasy driver does'nt pust the clutch in all the way. If the clutch isn't the problem the oil in the trans should be ATF and if someone put in 80-90 it'll do this but jumping out of high and the shifter isnt itting the floorboard as a bad trans mount or motor mount may let happen, The trans is damaged and a used unit is cheaper and quicker to get done. Rebuilding the trans with all the parts it may need cost more than your truck is worth

1991 Jeep... | Answered on Dec 05, 2009 | 417 views

When the car is completely cool,check the electric fan(s) for smooth rotation.

Clean/check/change the thermo sensor,contact and wire.


Excavate air pocket in coolant system / check for head gasket leak

This test will kill two birds with one stone.




You will spill some coolant during this air pocket purge test.......BE KIND TO THE ENVIRONMENT and ANIMAL please clean up after the test!


Put the front end on a pair of ramp or park your car on a VERY STEEP HILL (radiator facing top of the hill) .

Top of the coolant reserve tank

Let it ran for 10-15 minutes.

Monitor for air pockets escaping from coolant reserve tank.

Small amount of bubbles is OK at 1-5 minute mark

After the thermostat open up (after 195 F warm up) at
5-12 minute mark or after high idle you should see less bubbles.

If you do not see any in rush of bubbles then your thermostat may be partially stuck or rusted badly inside the thermostat hosing.

Give the thermostat host few gentle taps.

If you see larger bubbles surfacing after 15 minutes then should do a hydrocarbon (HC) dye test to test for potential head gasket leak.

Let engine cold down and top off coolant reserve tank.

Start monitor for coolant lost


A coolant flush is require every 2 years or 24,000 miles.

I recommend the thermostat that has a relief pop-let to reduce the change of burst radiator and coolant hoses.

Make sure you get a new thermostat gasket,black RTV and fresh coolant for the job.

Please post more information by clicking the comment link on the top right corner.

DON'T FORGET to RATE ME if my tip is helpful to you!

1991 Jeep... | Answered on Dec 05, 2009 | 1,013 views

the 4wd in a jeep is activated by vacum check all of the vacum system for leaks and the actuator motor on the front axel which is on the driver side in the middle of the axel tube. the motor if not used alot can lock up from time to time, that is where i would start, good luck hope this helps.

1991 Jeep... | Answered on Dec 05, 2009 | 77 views

Any time a change is made regarding either intake or exhaust flow, it is possible that you may exceed the working parameters of the control system. The loss of 3mpg is not large, but the amount of "built in" restriction the cat creates is not large either. With early carbureted engines that also had adjustable timing, it was easy to restore the proper fuel air mixture to the engine and therefore compensate for flow changes, A change such as removing the cat would often increase fuel mileage and add a few horsepower to your engine output. In today's systems, without adding special computer add- ons to enable reprogramming of the fuel and timing curve, that's pretty much impossible. Unfortunately, you likely need to put the cat back on.

1991 Jeep... | Answered on Dec 03, 2009 | 92 views

On the master cylinder housing where the hose goes in there a small roll pin knock it out and the hose will come right out.Is that the problem If the hose was leaking then yes. If you had a good clutch paddle no. If clutch paddle feels good more then likely it's going to be the clutch pressure plate. Replace with new or remfd. clutch set.

1991 Jeep... | Answered on Nov 20, 2009 | 112 views

see if your engine has a ECT sensor (temp sensor that delivers information to your ECM) they are installed on the intake side of the cylinder head, it usually has 2 cables, have it checked replace if necesary

1991 Jeep... | Answered on Nov 19, 2009 | 1,109 views

If you are positive that your fuel pump is not working, then it is time to replace it.

You can find the fuel pump either inside the engine compartment or inside the gas tank, depending on the engine that you have in your wrangler.

Since it is likely that you have the inline 6 cylinder 4.0, the pump is most likely inside the tank.

Go ahead and pull it if you are sure that is the problem and take it to be tested by your local auto parts store.

1991 Jeep... | Answered on Nov 11, 2009 | 324 views

Sounds like you have all the info you need but are afraid to try the job. Look under the P/S pump and you should see a bolt that runs under it (left to right). You don't loosen the pump pulley, but actually you loosen the pump itself. Loosening the bolt underneath will remove tension from the belt, tightening it will restore tension, but only after loosening the two bolts that allow the pump to slide back and forth on the mount bracket. Make sure you know where the belt goes before taking it off (draw a picture if you need to) and, remember it is very easy to overtighten it. after installing, belt should have about a half inch of deflection. Check this befrore starting and again after about an hour of running.

1991 Jeep... | Answered on Nov 09, 2009 | 144 views

No, There is no modifications of that sort to install a shifter if you have the application correct.. Oops, you mean remove? Still no. The floor should have a removable pan on the hump above the trans.

1991 Jeep... | Answered on Nov 09, 2009 | 223 views

no you cant for say the doors on the hard top are a little diff but you can use them to get buy if need be they just wont seal along the top rear

1991 Jeep... | Answered on Oct 22, 2009 | 158 views

the brake light wire on ALL cars trucks & s u v 's is the same. green & yellow are allways R&L turn & BRAKE

1991 Jeep... | Answered on Oct 15, 2009 | 99 views

If the light was flashing when it came on, then it means your engine is misfiring.

A solid light can mean anything from a loose/faulty gas cap to a transmission issue.

This light comes on when the computer detects a fault of some sort in its diagnostic tests. If it keeps detecting this issue, the light will remain on. If the light turns off, then it has detected that the issue may no longer be present.

In order to find out what the exact reason was for your light, You need to have your car computer scanned to retrieve the code that the computer would have stored when the light triggered. Most garages will do this free of charge. The code will tell you what may have caused the light to initially turn on.

1991 Jeep... | Answered on Oct 05, 2009 | 89 views

the fuel sending unit is probably stuck and need to replacing. common problems to many older vehicle it tend to read sometime correctly and sometime not at all. the sending unit will be in your gas tank.

1991 Jeep... | Answered on Sep 30, 2009 | 246 views

vaccum leak

1991 Jeep... | Answered on Sep 27, 2009 | 327 views

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