4x4tx

i have a 1990 jeep cherokee that i keep at my deer lease as a hunting vehicle. It has a lot of miles but has always been reliable until lately. It starts to knock and then dies at idle and sometimes even when putting around. The fuel pump is making noise when the key is on but you can really smell gas a lot, really all the time. It did back fire pretty bad the other day as well.

Another issue is it seems to be getting hot quickly. The vehicle was not used that much last few years but two years ago I had the gas tank pulled and cleaned along with new fuel filter.

it also has an electrical drain somewhere that I have to unhook the battery before I leave each weekend or it will be dead.

If any of these are common issues that have easy fixes I am all ears. Here is a pic , not a great one but one as i was going by one of my game cams.

VTJeep

good looking xj, man! all set fer huntin! anyways, is there a leak in gas lines/evap lines? (i dunno too much about the '90 xj's as i have a '99)

if its getting hot i wonder if tstat is faulty? or bad rad fluid? are you sure its getting hot, this is not based off of dummy gauge, right? just wonderin...

as for battery issue... ahhhh..... ummmm.... well..... maybe its not getting a solid ground? or there is a bad relay thats not shutting power off to something? take a volt meter and see if there is current to at electrical component when jeep is off????? i really dunno too much about this world, sorry!

4x4tx

thanks man, here is a beter pic.

dont really know, not really handy with this kind of stuff myself, just wondering if anyone knew off the top of their head what these issues might be.

Baseing it being hot off opening the hood and feeling the heat so quick after just a little use.

The dying im thinking is the fuel filter as it either has trash in it or the engine is not getting enough gas. we dont really ever run it very fast so thinking maybe i need to take it on the road and "blow out" the trash. We put fresh gas in it at the beg of oct but it did have 8 gal or so of gas that had been sitting there.

The electrical stuff, had a mechanic look at it and he never could figure it out lol

88Cherokee4x4

Bro thats a Nice Xj you got. But listen same thing started happening with my Old 93 Cherokee country, i would die when ever it wanted to, it would over heat after min of it being started, and it all started happinging after i hammerd it one day and it back fired.

cpnwrench

Howdy, good looking trackn jeep....

heres what you gotta check.....

fuelsmell..... charcoal canister hose might have craked or come off, check fuel rail whee injectors are see if they ar ewet when idling.

change plugs & wires, rotor, cap.

check MAP sensor.....and vacuum hoses..for the bucking and stumbling

for the overheat, flush radiator and replace thermostat. also check around the heater control valve ( the thingy with hoses going to it, left side of engine top) see if its leaking.

battery drain,,,,how old is battery? check all grounds for cleanliness and secured tight. (something I found on mine, but it takes time, take off turn signal lenses and check the bulb sockets for corrosion, one of mine was shorted to ground it was so corroded and drained battery overnight).

best of luck sir!

cpnwrench

DFlintstone

Just a couple thoughts. Some of the fuel I've gotten here in CA is crap. I store a little sometimes for the generators and water pump ect. It separates! Sometimes as much as a gallon of something in the bottom of a five gallon can in a week. I guess they get away with it as non carbonated engines with the fuel sloshing around in the tank end up OK. For me, some engines will run some on full choke. and some not.

Anyway your fuel may separate sitting like that, then your pump is sucking ethanol or something.

One trick for your battery drain is to put a digital meter on the battery and pull fuses one at a time. If you pull the fuse on the "leaking" circuit the voltage will go up a tad. Guess you could just hold the button to do the dome-light circuit.
Alternator diode? Good luck!

...x2 on MAP & vacuum lines.

4x4tx

Well this weekend the jeep died while driving around the lease and it will not crank....just running down the battery...been reading elsewhere that it could be the crank sensor?

cruiser54

Engine turns over with the starter but doesn't catch? That's called a crank-no start. Here's how to check your CPS:

Renix CPS Testing and Adjusting
　
　
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out the upper mounting hole, or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.

　
　
Revised 07-30-2012

4x4tx

Is what is unplugged in this picture the cps sensor? Also what is that cable that is broken and just sitting there was connected to the little box on the back of the wall there?

cruiser54

Yes. That is the CPS.
That hose is supposed to run from the throttle body to the MAP sensor on the firewall. It appears that it is broken/disconnected?
MAP sensor is that deallie on the firewall to the right of the valve cover, bolted to the rusty bracket.

RTorrez1

As for you battery discharge check out this video that fallenknight308 posted. It the 4th post at this link.
https://www.cherokeeforum.com/f2/battery-issues-154716/

4x4tx

Ok i opened up that cps sensor and it was oily in there..tried to clean it but still wouldnt start....ok on the broken hose, yeah looks like it just cracked in half...dont know how long its been broken but would that be causing my problem?

4x4tx

How many fuse boxes are there on the XJ and where are there locations? If its something like the glove box light heck I dont need that for hunting lol...We have just been disconnecting the negative cable every time we leave but that sure is a PIA!

tjwalker

1. Do you have spark? You really need to know that to help you plot out your strategy. Pull a plug, keep it attached to the plug wire, place the plug electrode near a good engine ground, have a buddy crank the engine while you watch. You are looking for a strong, BLUE, snapping spark. Yellow/orange/white spark indicates a weak spark which may not be strong enough to start the engine. (weak spark is often a weak ignition coil)

If you have NO spark, then test the crankshaft position sensor as cruiser has posted the procedure. It will only take a few minutes with a meter. You must verify that you have proper crank sensor operation. Without it, you won't have spark and you won't have fuel going TO the fuel injectors. The crank sensor is a VERY common failure on the Jeep 4.0 engine.

2. You must have a solid vacuum line leading to the map sensor! Be sure that vacuum line is pulling good vacuum.

4x4tx

Dont know about spark, jeep is out at the lease and I am back home. Next time I am out there I would double check that.

So with the broken map sensor line would that cause the jeep to do what? ? Not crank, overheat, die while driving?