Backfires in drive but is fine in neutral and reverse?

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Jun 24, 2015 | 02:51 PM

papaj

Thread Starter

Senior Member

Joined: Oct 2011

Posts: 674

Likes: 0

From: Westfield MA

Year: 1992

Model: Cherokee

Engine: 4.0L

Backfires in drive but is fine in neutral and reverse?

So my dad's 97 crapped out and he changed the Crank position sensor and the coil now it idles fine and goes fine in reverse but as soon as it goes forwards it stumbles. Do we have a short somewhere or is this something else? Thanks

Jun 24, 2015 | 06:24 PM

Bustedback

CF Veteran

Joined: Feb 2010

Posts: 12,367

Likes: 23

From: Oroville, CA

Year: 1995

Model: Grand Cherokee

Engine: 4.0 with all of the noise and clatter

Quote:

Originally Posted by papaj

Check the fuel pressure. Throwing a crank sensor and coil at it didn't fix it, it's just a fluke it started.

Jun 24, 2015 | 06:54 PM

tjwalker

CF Veteran

Joined: Nov 2010

Posts: 5,840

Likes: 117

From: In the middle of Minnesota!

Year: 1999

Model: Cherokee

Engine: 4.0

Any check engine light? Even if one isn't currently on, I'd recommend hooking up a scan tool or a code reader to see if there are any "pending" codes.

Verifying fuel pressure is a good idea. Should be 49 psi, plus or minus 5 psi for a 97. If there are no codes, I'd recommend you test the "throttle position sensor".