Hey y’all, new here so thanks for letting me be here. I need help!

I have a 1998 Jeep Cherokee XJ, in-line 6 with the 4.0. It has 230k on it, bought used with 215k or so. The current issue I am having is it doesn’t like rain or apparently cold weather. It’s my wife’s daily driver.

For the last year or so, it has had a hard time starting in the rain. When it does start right away, it will frequently die at speeds around 30 mph, and especially if driven through a puddle. I’ve never had it die at speeds above 35.

Today, my wife went to start it to go to work and it would crank but not start. She lightly feathered the gas pedal while cranking the engine and it eventually started and ran fine.

A couple suspicions. I found this other thread that cites a possible failing coolant temp sensor. See picture for details. That might be the rainy day culprit. My thought this morning is *shudder* the fuel pump. Could it be that when cold (it was 25 degrees F this morning) the fuel pump doesn’t want to work as intended?

Anyone with experience in similar issues here would be appreciated. Recently replaced throttle body position sensor as well as the crankshaft position sensor. Had plenty of gas. Oil change on the 1st of the year. I try to keep up with maintenance as best as possible.

Thanks very much!

 

Let's start with diagnosis instead of throwing parts at it.

The first thing I would do is gather some diagnostic information. What's your fuel pressure? To get this, you need to hook up a fuel pressure tester to your Schrader valve on your fuel rail.
Next, question whether your crankshaft position sensor is actually faulty or not. Did you buy one from the dealership or elsewhere? These Jeeps can be picky about sensors. I'm not saying the only quality sensor is from the dealership, but Advance and Auto Zone sensors for these Jeeps have been known to cause issues and a faulty crankshaft position sensor is right in line with symptoms you describe. Of course, so is a faulty fuel pump or fuel pressure regulator.
Next, get an OBD2 reader if you don't already have one. The plug-in version or bluetooth version, your choice. Let's see what the computer reads for certain parameters like the coolant temperature.
Next, what's the condition of your spark plugs?

 

And while talking about the 'basics', ensure your battery cables (connections) are clean and free of corrosion. And clean the ground cable to your engine ....and wiggle/reseat the engine-to-body ground strap and battery-to-body ground too. If they don't exist, add them. There are plenty of harness connections and connectors around the engine bay I would wiggle and/or disconnect, and reconnect to make sure they are all making good contact. Be careful you don't bend any connector pins in the process. Check for any damaged or cracked hoses. Make sure the PCV valve hose is good and rubber grommet is in good shape.

On the temp sensor, it's easy to ohm out (engine cold/engine hot) and compare to a temp/ohm table. That would help you rule that possibility out. Even a $5 Harbor Freight VOM tester will do the trick:
https://www.cherokeeforum.com/f2/coo...esting-188821/

If it does turn out to be the fuel pump, they're relative easy to replace on these Jeeps. It's possible w/o removing the tank. But even removing the tank isn't that big of a deal if you run it low-ish on fuel.

 

Total new guy here. I don’t have any of those testers except a multimeter so I’ll need to put together a list and see what I can do. Working with a pretty limited budget this month. An OBD2 reader might be good to have anyway though.

I got the CKSPS from O’Reilly’s. There was a code being thrown but don’t remember which.

Spark plugs were brand new when I bought it, I believe. Not sure. What’s the best way to tell?

Forgot to mention, I have a new distributor cap I installed, and I did see some corrosion on the old one.

 

Battery cables are good and clean, I did that not long ago (a couple months maybe).

I’m not familiar with the ground straps you mentioned but I can find them and then check them. Could a non-existent ground cause something like this? I was suspecting electrical because it seemed water caused most my trouble, but with this morning’s cold related incident I’m not sure.

The VOM tester I can get, there’s a Harbor Freight in town.

PCV valve? Unfamiliar to me.

 

Positive Crankcase Ventilation valve. Located at the top/front of the valve cover. If they become clogged, inopperable, or the hose or rubber valve cover grommet cracks it can cause a loss of vacuum. Engine vacuum is important b/c it's what causes the air/fuel to mix (boil) for optimal combustion. They're cheap and inspecting/replacing is part of routine maintenance.

https://www.freeasestudyguides.com/e...cuum-test.html

 

Got it. Will do some research. Thank you.

 

old-fashioned reply, but try spraying some WD40 around the distributor cap, back in the day, had an old Ford that used to need that..cheap thing to try

If it works, replace relevant ignition components, cap, rotor, wires

 

Every 30,000 miles spark plugs, wires, cap and rotor. Old plug wires hate humidity!!

 

Quick update. Checked all my grounds, cleaned them up. I also cleaned the IAC valve. Put it back together and would not stay started unless I used the gas. My battery voltage with lights and accessories on while the car is running is just under 12. As a test, I rev the engine while idling at park and let the RPMs drop suddenly. It tries to die, but eventually corrects itself in about five seconds. It will try to die when I drop the rpm after holding it at anything over 1700 RPM. I’m suspecting there’s an issue with the alternator. I’m also suspecting I have a problem with my fuel supply. Tried to get a fuel pressure tester at Harbor freight, but they led me astray and I got the wrong one. Any other advice now that I’ve got to this point?

 

Your symptoms point to low available battery voltage. At a slightly high idle, you should see approximately 14.4 volts on the battery using your DVM. Have battery "load tested" and have your alternator tested. Gotta resolve this before continuing to diagnose any other conditions that may or may not continue to exist.

 

I agree with this, you should have more than 12V with the engine running. Measure it at the battery terminals it should be about 14V with engine running

A few times and alt I have had a flat battery from leaving my headlights on, as my buzzer doesnt work (intending to rectify this issue one day)

So, I jump it with my Lithium jump pack, but it wont idle for a few minutes until the alt has charged the battery, the flat battery sucks the juice out of the jump pack, and I have to keep my foot on the gas pedal.

I have found that disconnecting the battery entirely and just leaving the lithium pack under the hood means it will idle straight up, and I have driven it like that when if I was running late. It is a 1000CCA model and is only about the size of a Bible

 

This can be tested, running, with even a cheap 10$ Harbor Freight version of a multimeter. Please keep your hands safe.

He gave you good advice on where to start your assessment of what's going wrong.






Good luck, GOD Bless.

 

I got my hands dirty yesterday and changed the alternator. Didn’t even have to take the support brace off. Upon inspecting the old alternator, the black plastic piece that holds the ground to the alternator was loose. The little nut under the ground was loose, and the plastic housing could slide partway off the alternator. So I suspect that was the problem. However, I changed it anyway. Runs good. 14.5-14.8v under full accessories. Full charge. Fingers crossed.

 

As for cranking a long time before starting, I think I had a dirty fuel injector. My neighbor has a couple jeeps of my era and he gave me some fuel stabilizer and fuel injector cleaner. That may not be the total solve but it seems to have helped.