Engine wants to try to die above 40mph Help!
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
the whole idea here is the exhaust pressure when reving the motor will make you hand get pushed awa from the pipe
CF Veteran




Joined: Nov 2010
Posts: 5,840
Likes: 117
From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
It is not replaced until symptoms/testing point directly to it.
That is why I recommended testing of both fuel delivery and for exhaust restriction. Hunches and guesses generally leave you with less money in your pocket and still symptomatic.
It could be something entirely different, but in my garage, those two things would be the absolute first things I rule in or out, with tests that can help you isolate the root cause.
Thread Starter
Seasoned Member
Joined: Oct 2010
Posts: 348
Likes: 1
From: Central Texas (Round Rock)
Year: 1999
Model: Cherokee
Engine: 4.0
The fuel filter on a 99 is part of the fuel pump assembly, which is located inside of the gas tank; tank has to come down to replace.
It is not replaced until symptoms/testing point directly to it.
That is why I recommended testing of both fuel delivery and for exhaust restriction. Hunches and guesses generally leave you with less money in your pocket and still symptomatic.
It could be something entirely different, but in my garage, those two things would be the absolute first things I rule in or out, with tests that can help you isolate the root cause.
It is not replaced until symptoms/testing point directly to it.
That is why I recommended testing of both fuel delivery and for exhaust restriction. Hunches and guesses generally leave you with less money in your pocket and still symptomatic.
It could be something entirely different, but in my garage, those two things would be the absolute first things I rule in or out, with tests that can help you isolate the root cause.
Thread Starter
Seasoned Member
Joined: Oct 2010
Posts: 348
Likes: 1
From: Central Texas (Round Rock)
Year: 1999
Model: Cherokee
Engine: 4.0
So I cranked it up, put a piece of paper in front of the tail pipe (touching) the exhaust pushed it away at idle...reved, it was a a steady stream of air, keeping the paper pushed away...little bit of white exhaust, but it is fairly cold here today..
Pulled the air filter cover and the filter is fine... seems like a good amount of black stuff inside the hose that goes from the filter housing to the manifold...
How would i check the fuel delivery?
Pulled the air filter cover and the filter is fine... seems like a good amount of black stuff inside the hose that goes from the filter housing to the manifold...
How would i check the fuel delivery?
Thread Starter
Seasoned Member
Joined: Oct 2010
Posts: 348
Likes: 1
From: Central Texas (Round Rock)
Year: 1999
Model: Cherokee
Engine: 4.0
Thread Starter
Seasoned Member
Joined: Oct 2010
Posts: 348
Likes: 1
From: Central Texas (Round Rock)
Year: 1999
Model: Cherokee
Engine: 4.0
Put it in Neutral and reved it, with paper at the pipe...same thing as when it was in park...steady stream...
of course there is not an rpm guage, so just had to guess at 3k rpms...
of course there is not an rpm guage, so just had to guess at 3k rpms...
Member
Joined: May 2010
Posts: 116
Likes: 1
From: Gads Hill, Ontario
Year: 1996
Model: Cherokee
Engine: 4.0
If the problem is fuel delivery problem, it will go lean - usually causing bucking or spitting when this happens. If the problem is clogged cat, it will go rich.
I had similar problem, had computer hooked up to see O2 sensor signal while driving. I confirmed clogged cat by removing the (upstream) O2 sensor and going for a drive. When I stepped on the gas, it sounded like a jet taking off, or a compressed air hose running full blast.
New cat = runs great now.
I had similar problem, had computer hooked up to see O2 sensor signal while driving. I confirmed clogged cat by removing the (upstream) O2 sensor and going for a drive. When I stepped on the gas, it sounded like a jet taking off, or a compressed air hose running full blast.
New cat = runs great now.
Thread Starter
Seasoned Member
Joined: Oct 2010
Posts: 348
Likes: 1
From: Central Texas (Round Rock)
Year: 1999
Model: Cherokee
Engine: 4.0
So, if the problem turns out to be the Cat... Can I just get one of these and replace it? http://www.autopartswarehouse.com/de...1&apwidzU9j4QV
is it that simple? Not that I want to spend money on this when I really need a roof basket..LOL...
is it that simple? Not that I want to spend money on this when I really need a roof basket..LOL...
Seasoned Member
Joined: May 2010
Posts: 406
Likes: 0
From: Suffolk long island
Year: 1994
Model: Cherokee
Engine: 4.0 L I6
cut the old one out, your prob not planning on welding so bolt it back on with u bolts, or better yet, hit up the exhaust shop or a welding shop and have them weld it on. If you dont get it on right and leak before the cat, your problems will remain or increase
Thread Starter
Seasoned Member
Joined: Oct 2010
Posts: 348
Likes: 1
From: Central Texas (Round Rock)
Year: 1999
Model: Cherokee
Engine: 4.0
If we cut it out, and just clamp a piece of str8 pipe in there until we can get a hold of the cat, would that work for a couple of weeks?
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
if the cat was plugged the exhaust would of not gotten stronger when reving check fuel pressure would be my next step
Seasoned Member
Joined: May 2010
Posts: 406
Likes: 0
From: Suffolk long island
Year: 1994
Model: Cherokee
Engine: 4.0 L I6
If the cats actually clogged than yes. Its not legal though, and IDK if your year has 02 sensors after the cat..probably not unless you live in CA


