97 ZJ Cranks, won't start

97 ZJ 5.2 Limited.

Was fine yesterday, this morning got in to go to work and it cranked like crazy but wouldn't start. Checked codes, showing 12, 21, 55. Checked all underhood fuses, all good. Swapped relays around, no joy. Standing behind it I can smell gas after cranking it for a while. No obvious drips underneath. Any thoughts?

On 5/27/2014 12:18 PM, J. Clarke wrote:
> 97 ZJ 5.2 Limited.
>
> Was fine yesterday, this morning got in to go to work and it cranked like crazy but wouldn't start. Checked codes, showing 12, 21, 55. Checked all underhood fuses, all good. Swapped relays around, no joy. Standing behind it I can smell gas after cranking it for a while. No obvious drips underneath. Any thoughts?

Gotta have fire, fuel, air and turbulence.
Sounds like the spark is missing.

Lynn

J. Clarke wrote:
> 97 ZJ 5.2 Limited.
>
> Was fine yesterday, this morning got in to go to work and it cranked
> like crazy but wouldn't start. Checked codes, showing 12, 21, 55.
> Checked all underhood fuses, all good. Swapped relays around, no
> joy. Standing behind it I can smell gas after cranking it for a
> while. No obvious drips underneath. Any thoughts?

12 = battery disconnected within 25 start/stops
21 = O2 sensor
55 = end of codes

None of those are critical or would prevent starting.


First check that your battery connections are nice and clean.
Then crawl under and check for a burned wire to the O2 sensor(s).

I suspect that isn't your problem though.
Likely the one thing that isn't checked which is lack of spark.
(i.e. dead coil)

You can test it with one of these.
http://www.harborfreight.com/inline-...ker-69014.html

The other code that didn't throw could be the dreaded CPS (Crankshaft
Position Sensor) fault. That will get you, but usually only happens
when hot.

First check spark.

--
-- DougW -- 93 ZJ 4.0 http://revbeergoggles.com
HESCO Supercharger - 300W Stereo PPI/Audio Control - Bilstein HD Shocks
Flowmaster Exhaust - rear DCpower - custom gauge install - Brembo Rotors
Banks Header - and BEER, in the fridge! Who says old=slow.

On Tuesday, May 27, 2014 6:00:24 PM UTC-4, DougW wrote:
> J. Clarke wrote:
>
> > 97 ZJ 5.2 Limited.
>
> >
>
> > Was fine yesterday, this morning got in to go to work and it cranked
>
> > like crazy but wouldn't start. Checked codes, showing 12, 21, 55.
>
> > Checked all underhood fuses, all good. Swapped relays around, no
>
> > joy. Standing behind it I can smell gas after cranking it for a
>
> > while. No obvious drips underneath. Any thoughts?
>
>
>
> 12 = battery disconnected within 25 start/stops
>
> 21 = O2 sensor
>
> 55 = end of codes
>
>
>
> None of those are critical or would prevent starting.
>
>
>
>
>
> First check that your battery connections are nice and clean.
>
> Then crawl under and check for a burned wire to the O2 sensor(s).
>
>
>
> I suspect that isn't your problem though.
>
> Likely the one thing that isn't checked which is lack of spark.
>
> (i.e. dead coil)
>
>
>
> You can test it with one of these.
>
> http://www.harborfreight.com/inline-...ker-69014.html
>
>
>
> The other code that didn't throw could be the dreaded CPS (Crankshaft
>
> Position Sensor) fault. That will get you, but usually only happens
>
> when hot.
>
>
>
> First check spark.

Had Geico to it to the mechanic and let him deal with it. Just as glad I did--turned out to be the fuel pump--another big repair to fix a small part.