1990 Jeep Cherokee LTD no start/no spark

I'll check that out and report back.
Jesse

K....injectors aren't firing. Can manually operate relay to activate
pump but when cranking the injectors won't pulse or let fuel through.
Sounds like CPS again, doesn't it? Mike, in regard to not enough
voltage at coil....there is 10 - 11 volts.

Jesse

Just a thought>>>>>>>>> Since you dropped in a newer engine, is it
possible you clipped a harness wire, that is is shorting itself out at
the firewall?

I had a new engine dropped into my Cherokee, it gave the same symptoms
you describe, and we finally found a frayed harness wire that kept
shorting out against the metal.


--
Knifeblade_03
------------------------------------------------------------------------
Knifeblade_03's Profile: http://www.automotiveforums.com/vbul...?userid=262826
View this thread: http://www.automotiveforums.com/vbul...d.php?t=559753

http://www.automotiveforums.com

There is a CPS or pickup module and ignition module inside the
distributor as well. The distributor got clocked in correct right?
That shouldn't interfere with the power though, just the timing. Hmm,
but the engine needs both CPS signals to fire up, if they are not in
sequence??...

Anyhow, the distributor should be clocked with #1 plug wire as far away
from the block as it can be or in the 6:00 position looking at it from
the side of the engine. The base only fits one way so it can bolt
down. It must be bolted in to make the ground path.

You are not getting any power to the fuel pump or ignition when cranking
correct?

They do use a modified ford starter system with a starter relay that has
a power bypass used during cranking. There are a couple green wires on
it. I have seen these wires get mixed up on several different engine
removal or burned harness jobs. If you have 10 volts at the coil during
'cranking', then this shouldn't be the issue.

I live in the rust belt, so grounds are normally the first thing I go
after. I use a booster cable from the battery negative to the engine,
then the distributor shaft, then the body just to verify the major
players are there.

I have also seen bad alternators suck the ignition down. I would be
tempted to unplug it just for the heck of it and try. Depending on the
alternator, the field wire tags the coil power.

Then just to toss a strange one in, if the battery has a bad cell, it
can still give enough power to crank, but the electronics won't turn
on. This is worse on the newer Chrysler made systems than the old ones
though.

I doubt it has any bearing at all, but the O2 sensors are bad. All the
Renix O2 sensors are under recall. That shouldn't affect the start
though...

A bad connection on the Throttle Position Sensor can affect starting
too.

There are a few more guesses for you.

It's likely something silly. I would appreciate the follow up.

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)

spydey wrote:
>
> K....injectors aren't firing. Can manually operate relay to activate
> pump but when cranking the injectors won't pulse or let fuel through.
> Sounds like CPS again, doesn't it? Mike, in regard to not enough
> voltage at coil....there is 10 - 11 volts.
>
> Jesse

solenoid is functioning properly, injectors still not firing.

Hmmm....

Ok, you have a MAP up on the center firewall that sends a signal to the
ICM under the coil, the CPS and distributor pickup, the throttle body
IAC and TPS....

How many ground wires do you have bolted to the dipstick mount bolt?
Mine have 4 with 2 eye loops. I have an 87 and an 88.

You are right about the real distributor clocking being closer to 5:00,
I looked. Book is different...

Does the fuel pump cycle on when the key first hits run? It's ground
might be on the inside firewall above the gas pedal. Something critical
grounds there anyway.

Something sounds like it is going on related to that circuit because of
the effect when you jumped the ballast resistor. The orange wire with
the stripe is the one linking the systems I think. I have seen one of
those pinched and have seen and heard of several melted enough to short
the system down, down behind the engine where the exhaust crosses over.
There is a sensor on the T-case or something down there.

Could you have blown a fuse link? They are coming off the
solenoid/relay at the same terminal as the battery cable.

I am out of ideas I think....

Mike

spydey wrote:
>
> solenoid is functioning properly, injectors still not firing.

We seem to be on the same wavelength here...I was just thinking of
checking the MAP and the fuseable links. I'll let you know.

Thanks again
Jesse

Hi Mike,

GREAT NEWS!!!!!!!!! Problem solved. You're not going to believe it
but it all comes down to wiring. (which I suspected in the first place
but thought I had eliminated that). I went back into the harness and
started checking wiring. I realized that when I was checking the
ground wires inside the wire loom that I missed about a 18 in section
just after the main splice on the firewall, engine side. They looked
good but decided to investigate further. Upon a more thorough visual
inspection I noticed two little pin holes where someone had apparantly
probed the wires at one point in time. Remembering that the customer
had told me he had submersed the jeep past the windsheild in soupy
water at one time I decided to remove the covering on the
wires.......They literally fell apart.

So....it all comes down to a bad ground. It was something simple but
hidden. Thanks again Mike for all your input, I work on these jeeps on
a daily basis and I've never had one baffle me in 10 years as much as
this one has. Thanks

Jesse

Thanks for the update!

Man, those damn grounds on the old Jeeps are bad enough without
intentional damage. If I have to probe a wire, I put a spot of RTV into
the hole to seal it or at least some dielectric grease. (after seeing
exactly the same thing you have found)

If that Jeep was playing in the puddles, you might want to check the
tranny fluid out for water. Jeep didn't put a high water vent on the
tranny like they did for the diffs and t-case.

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)

spydey wrote:
>
> Hi Mike,
>
> GREAT NEWS!!!!!!!!! Problem solved. You're not going to believe it
> but it all comes down to wiring. (which I suspected in the first place
> but thought I had eliminated that). I went back into the harness and
> started checking wiring. I realized that when I was checking the
> ground wires inside the wire loom that I missed about a 18 in section
> just after the main splice on the firewall, engine side. They looked
> good but decided to investigate further. Upon a more thorough visual
> inspection I noticed two little pin holes where someone had apparantly
> probed the wires at one point in time. Remembering that the customer
> had told me he had submersed the jeep past the windsheild in soupy
> water at one time I decided to remove the covering on the
> wires.......They literally fell apart.
>
> So....it all comes down to a bad ground. It was something simple but
> hidden. Thanks again Mike for all your input, I work on these jeeps on
> a daily basis and I've never had one baffle me in 10 years as much as
> this one has. Thanks
>
> Jesse