Cherokee fuel press

Guys, if You don't help, nobody will.
I have a '92 Jeep Cherokee 4.0 which has had a stalling problem
for a few years which no one can seem to fix. Any help would be greatly
appreciated.
Let's get started. When it comes to 2250 rpm (under load or
acceleration) seems like someone pinched the fuel line and it just
doesn't want to accelerate. After a while, 3-4 seconds, it accelerates
like nothing was wrong.
So, I've been writing to all you guys before and after all answers, I
tried to check everything possible before ask again. It took some time
because I'm seaman and mostly on a ship but after replacing part by
part, here I am, back here.
First, new fuel pressure regulator... nothing happened, then oxygen
sensor (it seemed like it measures wrong values), still same.
New fuel filter (yesterday), still same.
In Haynes manual I found how to test fuel press and I have just done the
same and found:
With or without vacuum line attached, pressure is 22 psi. So, I tried to
drive around with gauge connected and mounted inside the cabin. Happens
that in the moment of "stalling" press drops to 18 psi (!?). When it
comes to my 22, things goes fine.
But nothing like in Haynes about 31 to even 39 psi!?
I tried to pinch return hose (possible only down before tank, everywhere
is a plastic hose) and nothing changed, it stays on 22.
Few months ago, even a fuel pump was removed and I expected dirty inlet
filter (one like a nylon bag) but nothing was wrong, clean and fine
filter found.
One more thing, it happens even with a full tank of gas.
Please, this group is my only and last hope. I like this car but the
damn thing just doesn't want to perform like it should.
Many thanks and greetings from Croatia, Europe.

Weak fuel pump.

Spdloader


"Davey" > wrote in message
...
> Guys, if You don't help, nobody will.
> I have a '92 Jeep Cherokee 4.0 which has had a stalling problem
> for a few years which no one can seem to fix. Any help would be greatly
> appreciated.
> Let's get started. When it comes to 2250 rpm (under load or acceleration)
> seems like someone pinched the fuel line and it just doesn't want to
> accelerate. After a while, 3-4 seconds, it accelerates like nothing was
> wrong.
> So, I've been writing to all you guys before and after all answers, I
> tried to check everything possible before ask again. It took some time
> because I'm seaman and mostly on a ship but after replacing part by part,
> here I am, back here.
> First, new fuel pressure regulator... nothing happened, then oxygen
> sensor (it seemed like it measures wrong values), still same.
> New fuel filter (yesterday), still same.
> In Haynes manual I found how to test fuel press and I have just done the
> same and found:
> With or without vacuum line attached, pressure is 22 psi. So, I tried to
> drive around with gauge connected and mounted inside the cabin. Happens
> that in the moment of "stalling" press drops to 18 psi (!?). When it comes
> to my 22, things goes fine.
> But nothing like in Haynes about 31 to even 39 psi!?
> I tried to pinch return hose (possible only down before tank, everywhere
> is a plastic hose) and nothing changed, it stays on 22.
> Few months ago, even a fuel pump was removed and I expected dirty inlet
> filter (one like a nylon bag) but nothing was wrong, clean and fine filter
> found.
> One more thing, it happens even with a full tank of gas.
> Please, this group is my only and last hope. I like this car but the damn
> thing just doesn't want to perform like it should.
> Many thanks and greetings from Croatia, Europe.

I would be looking at the connection on the throttle position sensor
first. I use a spray contact cleaner on the connections on mine. WD40
will work as a connection cleaner too.

They are a rheostat and can get a dead spot, but their electrical
connection can cause hiccups like you describe too. You can use a
multimeter on ohms and take the readings as you open the throttle with
it unplugged and the engine off. It should change evenly. If the
resistance bumps, you likely have found the trouble.

I hear you can clean the guts of the TPS too, but have never needed to.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Davey wrote:
>
> Guys, if You don't help, nobody will.
> I have a '92 Jeep Cherokee 4.0 which has had a stalling problem
> for a few years which no one can seem to fix. Any help would be greatly
> appreciated.
> Let's get started. When it comes to 2250 rpm (under load or
> acceleration) seems like someone pinched the fuel line and it just
> doesn't want to accelerate. After a while, 3-4 seconds, it accelerates
> like nothing was wrong.
> So, I've been writing to all you guys before and after all answers, I
> tried to check everything possible before ask again. It took some time
> because I'm seaman and mostly on a ship but after replacing part by
> part, here I am, back here.
> First, new fuel pressure regulator... nothing happened, then oxygen
> sensor (it seemed like it measures wrong values), still same.
> New fuel filter (yesterday), still same.
> In Haynes manual I found how to test fuel press and I have just done the
> same and found:
> With or without vacuum line attached, pressure is 22 psi. So, I tried to
> drive around with gauge connected and mounted inside the cabin. Happens
> that in the moment of "stalling" press drops to 18 psi (!?). When it
> comes to my 22, things goes fine.
> But nothing like in Haynes about 31 to even 39 psi!?
> I tried to pinch return hose (possible only down before tank, everywhere
> is a plastic hose) and nothing changed, it stays on 22.
> Few months ago, even a fuel pump was removed and I expected dirty inlet
> filter (one like a nylon bag) but nothing was wrong, clean and fine
> filter found.
> One more thing, it happens even with a full tank of gas.
> Please, this group is my only and last hope. I like this car but the
> damn thing just doesn't want to perform like it should.
> Many thanks and greetings from Croatia, Europe.

Mike Romain wrote:
> I would be looking at the connection on the throttle position sensor
> first. I use a spray contact cleaner on the connections on mine. WD40
> will work as a connection cleaner too.
>
> They are a rheostat and can get a dead spot, but their electrical
> connection can cause hiccups like you describe too. You can use a
> multimeter on ohms and take the readings as you open the throttle with
> it unplugged and the engine off. It should change evenly. If the
> resistance bumps, you likely have found the trouble.
>
> I hear you can clean the guts of the TPS too, but have never needed to.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
>
Few months ago, Jeep was at authorised workshop and guy hooked it up
on some kind a multitester for Chrysler/Jeep and complete test passed
through all of electronic items and found nothing wrong. Guy told me he
has no time to drive around with "tester thing" so we couldn't see what
happens when it comes to loaded 2250 rpm.
Mike, what about this fuel pressure, can it be just a damn pump?
Logically, when you pinch return hose, pressure should jump very fast,
right?

Hi Davey,
I would guess it's at least the fuel regulator:
http://members.cox.net/wilsond/Fixes...tml#fuelsystem Pinch
off the return line and you should have ninety pounds, if not replace
the pump, too.
God Bless America, Bill O|||||||O
http://www.billhughes.com/

Davey wrote:
>
> Few months ago, Jeep was at authorised workshop and guy hooked it up
> on some kind a multitester for Chrysler/Jeep and complete test passed
> through all of electronic items and found nothing wrong. Guy told me he
> has no time to drive around with "tester thing" so we couldn't see what
> happens when it comes to loaded 2250 rpm.
> Mike, what about this fuel pressure, can it be just a damn pump?
> Logically, when you pinch return hose, pressure should jump very fast,
> right?

I'm with Bill on this one. You should have 30-31 PSI with vacuum, 41
PSI with vacuum off. The fact that it will recover and run at higher
RPM after the stagger suggests that the pump has adequate capacity.
Best thing I can suggest is to check the pressure with the return
pinched first. If that gives 90+ PSI (don't hold it pinched any
longer than necessary) but still reads much below 30 PSI you could
also try a flow check by pinching the return line and opening the
schraeder valve on the fuel rail to pipe the gas to a bucket. I don't
have the number handy, but you will need to see a couple of
liters/minute flow that way. Then go buy a pressure regulator -
your's isn't holding what it's supposed to by a long shot. When my
pump was dying, anything below 20PSI would start it to stuttering.

On Sat, 22 Apr 2006 22:54:50 UTC "L.W.(Bill) Hughes III"
> wrote:

> Hi Davey,
> I would guess it's at least the fuel regulator:
> http://members.cox.net/wilsond/Fixes...tml#fuelsystem Pinch
> off the return line and you should have ninety pounds, if not replace
> the pump, too.
> God Bless America, Bill O|||||||O
> http://www.billhughes.com/
>
> Davey wrote:
> >
> > Few months ago, Jeep was at authorised workshop and guy hooked it up
> > on some kind a multitester for Chrysler/Jeep and complete test passed
> > through all of electronic items and found nothing wrong. Guy told me he
> > has no time to drive around with "tester thing" so we couldn't see what
> > happens when it comes to loaded 2250 rpm.
> > Mike, what about this fuel pressure, can it be just a damn pump?
> > Logically, when you pinch return hose, pressure should jump very fast,
> > right?


--
Will Honea

The first thing I do with a suspected fuel problem is change the filter,
then blow the old one back into a cup to see what was in it, and how plugged
it was. Shiny metal flakes are usually pump, but some is normal
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

Hmm, guys, I told you that my filter is brand new, pressure regulator is
new, filter on pump inlet was clean but pressure still behaves strange.
With or without vacuum line attached, pressure is always only 22 psi.
So, I drove around with gauge connected and mounted inside the cabin.
Happens that in the moment of "stalling" press drops to 18 psi (!?),
then it comes back to my 22 and rises a little bit , thing goes quite fine.
But nothing like in Haynes about 31 to even 39 psi!? Never.
Such a pressure never happens, even if I pinch return line (this is
even pain in the ass because only place where I can pinch return line is
down below the car just before tank. Everywhere else is plastic hose.)
Last thing remaining is stupid fuel pump. Has anyone had any problem
with fuel pump and how these problems look like on those cars?
Yes, one more thing, pressure remains same for a loong period after the
car has been stopped, so I assume that any kind of non-return valves
inside are still in a good mode. And I remember, when I changed filter
(few days ago), pressure rose to just about 24 psi and everything else
remain same.

L.W.(Bill) Hughes III wrote:
> Hi Davey,
> I would guess it's at least the fuel regulator:
> http://members.cox.net/wilsond/Fixes...tml#fuelsystem Pinch
> off the return line and you should have ninety pounds, if not replace
> the pump, too.
> God Bless America, Bill O|||||||O
> http://www.billhughes.com/
>
> Davey wrote:
>
>> Few months ago, Jeep was at authorised workshop and guy hooked it up
>>on some kind a multitester for Chrysler/Jeep and complete test passed
>>through all of electronic items and found nothing wrong. Guy told me he
>>has no time to drive around with "tester thing" so we couldn't see what
>>happens when it comes to loaded 2250 rpm.
>>Mike, what about this fuel pressure, can it be just a damn pump?
>>Logically, when you pinch return hose, pressure should jump very fast,
>>right?

Weak fuel pump.

Spdloader



"Davey" > wrote in message
...
> Hmm, guys, I told you that my filter is brand new, pressure regulator is
> new, filter on pump inlet was clean but pressure still behaves strange.
> With or without vacuum line attached, pressure is always only 22 psi. So,
> I drove around with gauge connected and mounted inside the cabin. Happens
> that in the moment of "stalling" press drops to 18 psi (!?), then it comes
> back to my 22 and rises a little bit , thing goes quite fine.
> But nothing like in Haynes about 31 to even 39 psi!? Never.
> Such a pressure never happens, even if I pinch return line (this is even
> pain in the ass because only place where I can pinch return line is down
> below the car just before tank. Everywhere else is plastic hose.)
> Last thing remaining is stupid fuel pump. Has anyone had any problem with
> fuel pump and how these problems look like on those cars?
> Yes, one more thing, pressure remains same for a loong period after the
> car has been stopped, so I assume that any kind of non-return valves
> inside are still in a good mode. And I remember, when I changed filter
> (few days ago), pressure rose to just about 24 psi and everything else
> remain same.
>
> L.W.(Bill) Hughes III wrote:
>> Hi Davey,
>> I would guess it's at least the fuel regulator:
>> http://members.cox.net/wilsond/Fixes...tml#fuelsystem Pinch
>> off the return line and you should have ninety pounds, if not replace
>> the pump, too. God Bless America, Bill O|||||||O
>> http://www.billhughes.com/
>>
>> Davey wrote:
>>
>>> Few months ago, Jeep was at authorised workshop and guy hooked it up
>>>on some kind a multitester for Chrysler/Jeep and complete test passed
>>>through all of electronic items and found nothing wrong. Guy told me he
>>>has no time to drive around with "tester thing" so we couldn't see what
>>>happens when it comes to loaded 2250 rpm.
>>>Mike, what about this fuel pressure, can it be just a damn pump?
>>>Logically, when you pinch return hose, pressure should jump very fast,
>>>right?

Davey wrote:
>
> Mike Romain wrote:
> > I would be looking at the connection on the throttle position sensor
> > first. I use a spray contact cleaner on the connections on mine. WD40
> > will work as a connection cleaner too.
> >
> > They are a rheostat and can get a dead spot, but their electrical
> > connection can cause hiccups like you describe too. You can use a
> > multimeter on ohms and take the readings as you open the throttle with
> > it unplugged and the engine off. It should change evenly. If the
> > resistance bumps, you likely have found the trouble.
> >
> > I hear you can clean the guts of the TPS too, but have never needed to.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> > Canadian Off Road Trips Photos: Non members can still view!
> > Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> > (More Off Road album links at bottom of the view page)
> >
> Few months ago, Jeep was at authorised workshop and guy hooked it up
> on some kind a multitester for Chrysler/Jeep and complete test passed
> through all of electronic items and found nothing wrong. Guy told me he
> has no time to drive around with "tester thing" so we couldn't see what
> happens when it comes to loaded 2250 rpm.
> Mike, what about this fuel pressure, can it be just a damn pump?
> Logically, when you pinch return hose, pressure should jump very fast,
> right?

I live in the rust belt so usually look for bad connections first. They
are cheap and easy fixes. Our 88's fuel pump is run via a ceramic
ballast resistor that is out on the fender near the rad. That is open
to the elements and gets bad connections now and then.

The ground for the fuel pump is the body and the mesh strap from the
rear of the head to the firewall goes rotten easy not letting a
consistent circuit happen, but that usually causes stalls at speed like
a CPS going bad.

That TPS is known to give an acceleration hiccup though. It is cheap
and easy to clean it's connections just for the heck of it. Mine need a
clean it every two years or so.

I have seen fuel pump impellers come loose on Dodge and Chrysler
vehicles though. The suckers hum and draw power right, but just a
trickle comes out.

If you think you actually got the return line blocked, then that pump
could be suspect. Low power to the pump can cause it too though.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)