89 Jeep Cherokee Won't Start - No Fuel Injector Pulse

"whonea" wrote:
> Fuel pump won't stop the injectors from firing. I'm surprised
> at you,
> Mike. This is a perfect place to point to the ground strap
> <g>. Jump
> the battery negative to a clean bolt on the firewall and see
> what
> happens ( try jumpering to the ground lug on the firewall up
> by the
> MAP sensor - the one with the braided cable on it - as that's
> the
> cable that rots out).
>
> On Wed, 8 Jun 2005 18:40:18 UTC Mike Romain
> >
> wrote:
>
> > The ballast resistor for the fuel pump is out on the drivers
> side fender
> > by the radiator.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in
> '00
> > 88 Cherokee 235 BFG AT's
> >
> > langer1 wrote:
> &nbsp;> >
> &nbsp;> > "sevensixtwo_fmj" wrote:
> &nbsp;&nbsp;> > > Hey,
> &nbsp;&nbsp;> > > actually Help!
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > > Here's my symptoms:
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > > 1. Cranks fine
> &nbsp;&nbsp;> > > 2. Lots of good spark
> &nbsp;&nbsp;> > > 3. Timing was set TDC on compression
> stroke.. verified twice.
> &nbsp;&nbsp;> > > 4. Fuel Rail is pressurized
> &nbsp;&nbsp;> > > 5. Crank Pos Sensor functional (as far as
> we can tell)
> &nbsp;&nbsp;> > > 6. Map Sensor Functional (voltage too the
> sensor)
> &nbsp;&nbsp;> > > 7. Throttle Position Sensor is functional
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > > Big clue is the following and explains why
> its not firing:
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > > We stuck a Noid light on two or three
> injector plugs and
> &nbsp;&nbsp;> > > there's no pulsing to the injectors. This
> explains the lack
> &nbsp;&nbsp;> > > of starting. But WHY??? What could cause
> the fuel injectors
> &nbsp;&nbsp;> > > not
> &nbsp;&nbsp;> > > to be pulsed.
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > > We haven't done a compression test but
> we've got a
> &nbsp;&nbsp;> > > professionally
> &nbsp;&nbsp;> > > built long block so I'm not sure it needs
> to be done...
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > > Any thoughts or insight would be
> appreciated..
> &nbsp;&nbsp;> > > HELP HELP HELP
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > > Thanks
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > > James
> &nbsp;> >
> &nbsp;> > Having pretty much the same problem.
> &nbsp;> > It seemed to start with the sensor on the flywheel
> so that was
> &nbsp;> > replaced.
> &nbsp;> > The next time it stopped I had some test equiepment
> with me and I had
> &nbsp;> > no fuel pressure, replacing the relay seemed to fix
> it but not for
> &nbsp;> > long.
> &nbsp;> > Next came the fuel pump and filter, seemed to fix it
> but not for long.
> &nbsp;> > I have checked all the ground wires, I have no power
> to pump, fuel
> &nbsp;> > pump relay pulls in for three seconds, pump does not
> run, there is no
> &nbsp;> > ballist resistor anywhere to be found.
> &nbsp;> > On the drivers side fender there is a EGR selonoid
> and a relay that
> &nbsp;> > should be the fan control.
> &nbsp;> > This is a 87 AMC 4.0.
> &nbsp;> >
> &nbsp;> > --
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>
>
> --
> Will Honea

Ground strap is good, tryed a jumper though and cleaned connections,
still pump don’t run and can’t find any ballist resistor. Here’s a
picture of driver side, nothing under washer bottle either.

http://img.photobucket.com/albums/v1...p/IM000365.jpg

langer1 wrote:

>
> Ground strap is good, tryed a jumper though and cleaned connections,
> still pump don’t run and can’t find any ballist resistor. Here’s a
> picture of driver side, nothing under washer bottle either.
>
> http://img.photobucket.com/albums/v1...p/IM000365.jpg

Ok, I would then be opening up the loom just below that vacuum thing out
on the fender to look for two orange wires twisted together with the
thoughts of finding a corroded connection or failed crimp where someone
bypassed the resistor.

Or looking up on the firewall for one. It is the typical chrysler
ceramic one.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

"Mike Romain" wrote:
> langer1 wrote:
>
> >
> > Ground strap is good, tryed a jumper though and cleaned
> connections,
> > still pump don’t run and can’t find any ballist resistor.
> Here’s a
> > picture of driver side, nothing under washer bottle either.
> >
> > http://img.photobucket.com/albums/v1...p/IM000365.jpg
>
> Ok, I would then be opening up the loom just below that vacuum
> thing out
> on the fender to look for two orange wires twisted together
> with the
> thoughts of finding a corroded connection or failed crimp
> where someone
> bypassed the resistor.
>
> Or looking up on the firewall for one. It is the typical
> chrysler
> ceramic one.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's

If you look ar the above picture.
Just down from the right corner of the Air Box, there is a small
orange block/socket sticking up, the orange wire’s go to it.
Plugged in to that block is what, at first, looks like a fuse.
But it’s a diode with <- +> on it. Sure looks like it’s in the fuel
pump circut.

--
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langer1 wrote:
>
> "Mike Romain" wrote:
> > langer1 wrote:
> >
> > >
> > > Ground strap is good, tryed a jumper though and cleaned
> > connections,
> > > still pump don’t run and can’t find any ballist resistor.
> > Here’s a
> > > picture of driver side, nothing under washer bottle either.
> > >
> > > http://img.photobucket.com/albums/v1...p/IM000365.jpg
> >
> > Ok, I would then be opening up the loom just below that vacuum
> > thing out
> > on the fender to look for two orange wires twisted together
> > with the
> > thoughts of finding a corroded connection or failed crimp
> > where someone
> > bypassed the resistor.
> >
> > Or looking up on the firewall for one. It is the typical
> > chrysler
> > ceramic one.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
>
> If you look ar the above picture.
> Just down from the right corner of the Air Box, there is a small
> orange block/socket sticking up, the orange wire’s go to it.
> Plugged in to that block is what, at first, looks like a fuse.
> But it’s a diode with <- +> on it. Sure looks like it’s in the fuel
> pump circut.
>
> --

Did you test it? Could just be popped.

If it is the orange wires, then I would carefully bypass it or
temporarily use an inline fuse on it to see if the pump comes back on.

Mike

"Mike Romain" wrote:
> langer1 wrote:
> >
> > "Mike Romain" wrote:
> &nbsp;> > langer1 wrote:
> &nbsp;> >
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > > Ground strap is good, tryed a jumper though
> and cleaned
> &nbsp;> > connections,
> &nbsp;&nbsp;> > > still pump don’t run and can’t find any
> ballist resistor.
> &nbsp;> > Here’s a
> &nbsp;&nbsp;> > > picture of driver side, nothing under
> washer bottle either.
> &nbsp;&nbsp;> > >
> &nbsp;&nbsp;> > >
> http://img.photobucket.com/albums/v1...p/IM000365.jpg
> &nbsp;> >
> &nbsp;> > Ok, I would then be opening up the loom just below
> that vacuum
> &nbsp;> > thing out
> &nbsp;> > on the fender to look for two orange wires twisted
> together
> &nbsp;> > with the
> &nbsp;> > thoughts of finding a corroded connection or failed
> crimp
> &nbsp;> > where someone
> &nbsp;> > bypassed the resistor.
> &nbsp;> >
> &nbsp;> > Or looking up on the firewall for one. It is the
> typical
> &nbsp;> > chrysler
> &nbsp;> > ceramic one.
> &nbsp;> >
> &nbsp;> > Mike
> &nbsp;> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to
> tail in '00
> &nbsp;> > 88 Cherokee 235 BFG AT's
> >
> > If you look ar the above picture.
> > Just down from the right corner of the Air Box, there is a
> small
> > orange block/socket sticking up, the orange wire’s go to it.
> > Plugged in to that block is what, at first, looks like a
> fuse.
> > But it’s a diode with &lt;- +&gt; on it. Sure looks like
> it’s in the fuel
> > pump circut.
> >
> > --
>
> Did you test it? Could just be popped.
>
> If it is the orange wires, then I would carefully bypass it or
> temporarily use an inline fuse on it to see if the pump comes
> back on.
>
> Mike

Crank Pos Sensor functional (as far as we can tell)

Every three to six months I have to disconnect and reconnect CPS to
get vehicle to start. Previous owners had lots of troubleshooting done
to find this intermittent problem [replaced original, still had
problem eventually] - even gave me a new one with the vehicle [which I
still have] - I have put over 100k miles on this ride in the last 6
years, and still ’Every three to six months I have to disconnect and
reconnect CPS to get vehicle to start...’

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cno wrote:
>
> "Mike Romain" wrote:
> > langer1 wrote:
> > >
> > > If you look ar the above picture.
> > > Just down from the right corner of the Air Box, there is a
> > small
> > > orange block/socket sticking up, the orange wire’s go to it.
> > > Plugged in to that block is what, at first, looks like a
> > fuse.
> > > But it’s a diode with &lt;- +&gt; on it. Sure looks like
> > it’s in the fuel
> > > pump circut.
> > >
> > > --
> >
> > Did you test it? Could just be popped.
> >
> > If it is the orange wires, then I would carefully bypass it or
> > temporarily use an inline fuse on it to see if the pump comes
> > back on.
> >
> > Mike
>
> Crank Pos Sensor functional (as far as we can tell)
>
> Every three to six months I have to disconnect and reconnect CPS to
> get vehicle to start. Previous owners had lots of troubleshooting done
> to find this intermittent problem [replaced original, still had
> problem eventually] - even gave me a new one with the vehicle [which I
> still have] - I have put over 100k miles on this ride in the last 6
> years, and still ’Every three to six months I have to disconnect and
> reconnect CPS to get vehicle to start...’
>
> --

I got good advise on those plug and sockets, same for the throttle body
ones like the TPS and it was to do the same thing.

I went one better and recommend a spray contact cleaner inside them with
a smear of dielectric grease on the plug's sealing skirts. I get a good
2 or more years out of them before having to clean them again that way.

WD40 will sort of work as a contact cleaner in a pinch, but the fix
doesn't seem to last long. Real electronic cleaner is the best.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's