Idles rough, bogs down with gas, generally just running badly?

Tiny
KNOWHEREMAN90
  • MEMBER
  • 2000 DODGE DURANGO
  • 5.9L
  • V8
  • 4WD
  • AUTOMATIC
  • 250,000 MILES
About a week ago it randomly started to bog down while I was driving, has a rough idle, and the hole car is shaking pretty much all of the time. In the last month I've replaced the PCM, alternator, spark plugs and the tubes/wires that plug into them, distributor cap, ignition coil, O2 sensor, MAP sensor, idle air control valve, oil change, blower motor, and serpentine belt (it does look like the belt tensioner is a little loose, and the belt is squeaking).
Saturday, September 23rd, 2023 AT 9:14 PM

8 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,101 POSTS
Hi,

Is the check engine light staying on while the engine is running? If it is, have you had the computer scanned for diagnostic trouble codes?

When I read through the symptoms, the first thing I thought was an issue with fuel pressure. Have you noticed any dark smoke from the exhaust or odd smells? Also, have you checked for engine vacuum leaks?

Take a look at these three links. One explains how to test fuel pressure, one is for vacuum leaks, and one is for a possible plugged catalytic converter. These are the first things I would check.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Let me know your thoughts. I normally don't like giving three different possibilities, but your description made me think in a few different directions. LOL I have a feeling it is fuel pressure related, so start with that one. You will need a fuel pressure gauge, but most parts stores will lend one to you.

I attached the manufacturer's fuel pressure specifications below for you.

Let me know what you find.

Take care,

Joe

See pic below.

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Saturday, September 23rd, 2023 AT 9:59 PM
Tiny
KNOWHEREMAN90
  • MEMBER
  • 5 POSTS
Hey Joe, sorry for the late response, it took me a bit to get a fuel pressure tester. So, when I turn the key to on, the gauge goes up to about 20 and it's pulling some fuel into the line (not sure if that's normal or not), with the car running it hovers around 50. I replaced the bad belt tensioner pulley and idler pulley, but the tensioner is still jumping back and forth when the car is running.
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Monday, September 25th, 2023 AT 6:22 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,101 POSTS
Hi,

The fuel pressure doesn't sound right. It should be higher when the engine is off. Also, what line is drawing fuel? Is it a vacuum line at the regulator?

As far as the belt is concerned, let's get it running properly first and see what happens. If we can smooth the engine down, the tensioner may follow suit.

Let me know about the hose you are referring to.

Take care,

Joe
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Monday, September 25th, 2023 AT 7:44 PM
Tiny
KNOWHEREMAN90
  • MEMBER
  • 5 POSTS
After letting the car run for a couple min, when checking the fuel pressure, it would initially jump to 40ish, and then every subsequent test would be lower and lower. I attached another video. You can hear how bad it sounds after I give it gas.
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Monday, September 25th, 2023 AT 7:52 PM
Tiny
KNOWHEREMAN90
  • MEMBER
  • 5 POSTS
I'm not really sure but I'll post a picture.

*The gold cap is where I have the tester connected.
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Monday, September 25th, 2023 AT 7:54 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,101 POSTS
Hi,

The pressure when the key is first turned on should be much higher than 20 psi. Interestingly, when you have it running, it jumps to the normal range. However, I noticed when you hit the throttle, the gauge didn't jump.

I suspect it is the fuel filter/regulator issue. This component is located at the top of the fuel tank and fuel module. See pics below. See number 1 in pic 1 and number 3 in pic 2.

That is my first suspect. It requires the removal of the fuel tank to be replaced. Starting with pic 3, I attached the directions for the replacement of the component. Take a look through them and let me know if you have questions or are comfortable performing them.

If this was my vehicle, I would likely remove and replace the fuel pump assembly at the same time. You wouldn't want to remove the tank again. It's just a thought.

Take care,

Joe

See pics below.
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Monday, September 25th, 2023 AT 8:16 PM
Tiny
KNOWHEREMAN90
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I ordered one off Amazon, is this everything I'm going to need?
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Tuesday, September 26th, 2023 AT 10:15 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,101 POSTS
Hi,

Yes, that appears to be everything. I see the regulator/filter on the top.

If you have a chance, let me know how things turn out for you.

Take care,

Joe
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Tuesday, September 26th, 2023 AT 12:55 PM

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