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My Jeep is being a Jerk!

I have a 1999 Jeep Cherokee Sport with 104K miles. It’s been a great vehicle with minimal mechanic issues over the last ten years. I service it regularly with oil changes and the manufacturer’s suggested maintenance.

Over the last year, it hasn’t been running properly from a sound and feel (and presumably mechanical) perspective. This “problem” is not present when the car has been running and is “warmed up” (i.e., after about three minutes of use). The symptoms are also more intense, the longer the car sits unused (i.e., overnight vs. over a weekend).

Basically, when I start the car and push the gas it’s not smooth and the acceleration is not consistent. The car is jerky and only accelerates (i.e., with the engine revving up) in quick sporadic intervals. I also hear/feel a clicking sound – almost like a mild backfire (i.e., spark of some sort).

When my foot is NOT on the gas, the engine idles low and in a few instances has shut off.

Anyone know why my Jeep is being a jerk?!

It certainly sounds like a weak fuel pump or bad fuel pressure regulator.

These are easy to test. A Haynes manual and a fuel pressure test kit from the parts store will answer the question for certain.

Thank you!

Just by the names of those car parts, it seems like they may be key to fixing the issue.

You say they are easy to test, but if they need to be repaired or replaced is that easy too? Is it costly or time consuming? I’d be taking it to my mechanic, so I just want an idea of the monetary investment I’d be making.

Be prepared for your mechanic to come up with a entirely different diagnosis,he can actually see,hear,test and feel how the car is running,much different than a internet diagnosis.

Agreed. And understood. I wasn’t going to run with this internet diagnosis as fact, but it was a helpful starting point. I’ll certainly use this information with discretion.

The regulator is easy to change, he pump is not. It’s mounted on top of the gas tank and sticking down into the gas.

But Oldschool makes an excellent point, as usual. My thoughts were conveyed to suggest a direction to go looking based on the symptoms and your comment that all the maintenance has been kept up. In truth it could end up being something enirely different, like perhaps a failing ignition system component.

The tests I recommended are good DIY things, low in cost, low risk, low investment, and fitting the symptoms. They were offered based on my assumption that you’d be looking into this yourself. The Haynes manual is a great way to educate yourself, but if you plan on taking it to your mechanic anyway, let him do the diagnosis. If you’re friendly enough with him and he’s not too busy he may even show you what he’s doing.

Thank you, The Same Mountainbike. Your responses to my post were very informative. I understand these are not definitive conclusions on the problem, but they’ve helped me narrow in on likely suspects.