Rough idle, dies when I give it gas

X

*xj-man*

NAXJA Forum User

Location

bel air maryland

• Jan 3, 2011

• #1

Any clues? I have a 1994 Cherokee and I'm having the hardest time trying to figure it out. So far I've replaced

O2 sensor
Every sensor on the throttle body
Fuel Filter
TPS

Heres the problem: Starts fine runs for about 4 seconds, until it begins to idle then either has a rough idle or it dies. Usually it runs slightly better whenever its colder but not for long. However whenever I press on the gas it almost automatically dies.

 

bcmaxx

NAXJA Forum User

Location

The West Kootenays,B.C. Canada

• Jan 3, 2011

• #2

Check your map sensor, and the little vacuum tube going to it

 

D

dennis461

NAXJA Forum User

Location

Waterford Township, NJ

• Jan 3, 2011

• #3

Does it backfire through the intake when it dies?

 

joe_peters

NAXJA Forum User

Location

Grants Pass, OryGun

• Jan 3, 2011

• #4

Hmm...

What TESTING have you done?

Put a fuel pressure gauge on it and post up the numbers.

 

M

MachRanger

NAXJA Forum User

Location

Waynesville, MO

• Jan 4, 2011

• #5

Have you pulled the plugs and checked them? See what the electrodes look like or maybe if you have a cracked insulator on one or more.

 

B

birchlakeXJ

NAXJA Forum User

Location

Melrose, MN

• Jan 4, 2011

• #6

1. Always review tuneup hardware when symptomatic. Fresh champion copper plugs, new wires, cap, rotor.

2. Testing fuel pressure is one of the first things that should be done. Could be something else, but proper fuel delivery should be ruled in or out early in the game. You can rent a gauge if you don't have access to one from a parts store for a few bucks.

 

E

ERock62

NAXJA Forum User

Location

Duarte, CA.

• Jan 4, 2011

• #7

Sounds very similar to my 93 XJ when my fuel pump died

 

X

*xj-man*

NAXJA Forum User

Location

bel air maryland

• Jan 5, 2011

• #8

Haven't really done much testing, I checked the fuel rail and it does have fuel pressure.
I replaced the fuel pump in the summer but that doesnt mean its not bad..
I also replaced the plugs about 4 weeks ago.
and it does backfire occansionaly but once or twice

Checked the MAP sensor and thats fine.

 

Last edited: Jan 5, 2011

B

birchlakeXJ

NAXJA Forum User

Location

Melrose, MN

• Jan 5, 2011

• #9

Still gotta verify fuel pressure............rent a gauge. Can't tell anything by just looking for fuel pressure at the rail. Must be measured.

As you mentioned, just because you replaced the pump last summer doesn't mean that fuel delivery is in spec. Newer parts fail all the time. What brand pump did you use? Just curious..............

 

X

*xj-man*

NAXJA Forum User

Location

bel air maryland

• Jan 5, 2011

• #10

Can't recall want brand fuel pump that is.. I guess I'll check the fuel pressure.
I hoped it was just a sensor or an easy fix.

 

B

birchlakeXJ

NAXJA Forum User

Location

Melrose, MN

• Jan 5, 2011

• #11

Post up the pressure numbers.

If you replace, stay away from Airtex pumps if there are other options at the parts stores. Not the best choice in my opinion (and other threads on this and other XJ forums back this up).

 

joe_peters

NAXJA Forum User

Location

Grants Pass, OryGun

• Jan 5, 2011

• #12

birchlakeXJ said:

Post up the pressure numbers.

If you replace, stay away from Airtex pumps if there are other options at the parts stores. Not the best choice in my opinion (and other threads on this and other XJ forums back this up).

Click to expand...

IMHO Bosch is the only pump worth a damn. www.rockauto.com has some great sales on them a couple times a year--last spare I bought for my 90 was $72 to my door!!