Engine turns over, but takes a while to get going

Hello.

I own a 98 Jeep Classic 4.0 6 cylinder with what I believe to be called a manual shift on the fly transfer case. Sorry. New to the 4x4 scene. She's got 130k miles.

I just drove my new-to-me jeep from Southern California to Colorado where I've decided to live. Elevation change is approximately 5000 ft. Not sure if that requires me to adjust my timing like the guy at O'Reileys suggested.

Issue: Typically when on the colder side, my engine is having trouble firing up. I turn the key, give the electronics a few moments to wake up, and then turn to ignition. She seems to turn over just fine, but it takes a long 2-5 seconds to get going. I've had the battery tested twice in the past few weeks and both readings have been at or near perfect. A mechanic told me that it should fix itself after a few weeks of my computer realizing my new environment. An older post I found in our forums led me to believe that it might be my injectors. Any confirmation or solid redirection would be appreciated.

Thank you.

Are ALL the tune-up parts fresh ? Cleaned the Throttle Body and Idle Air Controller recently ? Used any good quality fuel injector cleaner in the gas tank ? 2-5 seconds is not unusually long for start-up.

You can do some research on the Check Valve which is a common failure leading to longer start times.

The tune-up parts are not fresh, but inspected and okay. I should probably learn to identify the throttle body and idle air controller before I look to clean them. And I'm going to pick up some injector cleaner tomorrow.

Thanks for the response!

A dirty Idle Air Control Valve is usually associated with rough idle. You will know when it's dirty, believe me.


What you are describing, and my XJ suffers the same issues, is what seems to be caused by the check valve in the fuel pump. What the check valve is supposed to do is make sure the fuel rail maintains a certain pressure. I checked my rail pressure with a gauge I borrowed from advance and I could see the fuel pressure drop VERY quickly when I turned off the engine. Unless someone corrects me that is the check valve. I've been living with the issue for some time now. Worst thing is that it puts extra work on the starter.


When I park my Jeep nose up on an incline I really notice the difference. Gravity is a ***** after all...

If this is your worst problem after a good tune up you can live with it. Replacing the check valve involves dropping the fuel tank and replacing the pump assembly. Not a major deal but it can be a PITA.


While you're tuning up your XJ here are a couple tips.

Flush your cooling system NOW! These Jeeps are bad for clogging radiators and heater cores and are prone to overheating. Ask me how I know.
CLEAN YOUR COOLING SYSTEM!!! LOL Sorry to yell, but it's important.

Check your front end and steering components and replace as needed. These Jeeps are prone to an issue known as Death Wobble so don't let your front end go unchecked.

Basically, if you maintain these Jeeps you will get YEARS and YEARS of good service from them. These issues I've mentioned are issues I've had to resolve or live with on my own Cherokee. Good maintenance would have prevented most of it.


Welcome to the Cherokee Family!!!

Awesome. Thanks for all the information!

And if we were to imagine me as someone who never did his own time up, and more or less depended on a mechanic the majority of the time, it would probably behoove me to know that "tune-up" implies checking the spark plugs, battery power, inspecting and (if necesaary) replacing hoses, inspecting brakes and checking fluids...?

i want to say that the map could be to blame. also try disconnecting the battery for a couple of minutes to reset the ecu.

Try turning the key forward 2 or 3 times before actually trying to start it..

dobesrgrt said:

Try turning the key forward 2 or 3 times before actually trying to start it..

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Do what?

What does this do besides prime the fuel rail the same as cranking it would do?

turning the key to the run (not start) position will fire the fuel pump for a few seconds...building pressure. If it starts quicker after doing this a couple (2) times, the check valve could be to blame for the longer start times. As said previously, 2-5 seconds in not unusual for XJ's as the computer needs to see at least 300 rpm to fire everything.

Secondly, don't trust that "mechanic" at the parts store. XJ's timing is not adjustable...set by the computer.

My XJ is older ('89), but "tune up" usually means new cap/rotor (if you have those), plug wires (if they're old), and spark plugs gapped correctly (0.35, IIRC). My XJ doesn't like the fancy spark plugs...use OEM plugs (Champions?). They'll work just fine!

And, enjoy Colorado. I lived there for 15 years before being able to move back to Montana...the "last best place"...LOL

Naturally, now that I'm looking for the problem, it seems to have subsided. Whatever. Thanks for the input. I need to set aside some time to spend with the Jeep.

Before the coil died on my Jeep, I was noticing that it took longer and longer to start. In Hindsight, this was an indication of the pending failure, but I wrote it off to the pressure leak-down on the fuel rail caused by a bad check valve, like everyone else is saying.

Now, to be fair, I also replaced the fuel pump and filter before I got the Jeep running again, so this may have helped a bit. However, changing the pump does not change the regulator and check valve.

Napa was more than happy to sell me a new coil for $50, which is kinda expensive if you don't know for sure it's bad, but it's at least another thing to think about if changing the check valve doesn't fix the problem.

BartsXJ said:

Naturally, now that I'm looking for the problem, it seems to have subsided. Whatever. Thanks for the input. I need to set aside some time to spend with the Jeep.

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This is how it always works.

But yeah, take some time, do a good inspection of the engine, plugs, transmission etc etc. There is a world of information on here to help you figure out what to look for.

Do the basics for a tune up and then re-inspect. That way you have a solid foundation on which to base future concerns.

These trucks are GREAT vehicles but the newest one is at least 11 years old so expect maintenance to be a regular part of your life.


PEACE