LOST JEEPS :: View topic - Cranks but only starts with accelerator pedal depressed

New to forum got an 05 KJ that will crank with key an attempt to start but then won't. If you plant accelerator to the floor will start but runs rough and feathering throttle will keep going but it dies if you let off throttle the may or may not start the same way.

Things I've checked:
Spark-all coils are providing spark checked with plugs saw spark on all with my own
eyes

Injectors-Ohms are all 11.3 except one is 16, all are receiving power when back probed(have not checked with noid light when running)

Fuel pressure-checked with gage primes to 50 and holds when starting and when i get it to run as described before

Idle air control-removed and valve moves freely with little to no effort(unplugged and no change but will record code that it is not present),(havent checked any other way)

Tps-getting power will register on multimeter through full range

Replaced crank and cam position sensors with used sensors but was doing with old sensors already

Bought as a project that failed after shutting off in a parkinglot then began cranking as described.

Key on key off X3 will show codes on dash display. Pcm cleared daily due to interior lights are always on even after changing multiswitch on column, so cant leave battery attached.

Any great KJ techs that can give me some next step ideas to check?

Author:	CFAARON05 [ Sun Jun 02, 2024 7:07 pm ]
Post subject:	Cranks but only starts with accelerator pedal depressed
New to forum got an 05 KJ that will crank with key an attempt to start but then won't. If you plant accelerator to the floor will start but runs rough and feathering throttle will keep going but it dies if you let off throttle the may or may not start the same way. Things I've checked: Spark-all coils are providing spark checked with plugs saw spark on all with my own eyes Injectors-Ohms are all 11.3 except one is 16, all are recieving power when back probed(have not checked with noid light when running) Fuel pressure-checked with gage primes to 50 and holds when starting and when i get it to run as described before Idle air control-removed and valve moves freely with little to no effort(unplugged and no change but will record code that it is not present),(havent checked any other way) Tps-getting power will register on multimeter through full range Replaced crank and cam position sensors with used sensors but was doing with old sensors already Bought as a project that failed after shutting off in a parkinglot then began cranking as described. Key on key off X3 will show codes on dash display. Pcm cleared daily due to interior lights are always on even after changing multiswitch on column, so cant leave battery attatched. Any great KJ techs that can give me some next step ideas to check?

Author:	CFAARON05 [ Mon Jun 03, 2024 12:14 pm ]
Post subject:	Re: Cranks but only starts with accelerator pedal depressed
Update: took IAC out to clean due to being dirty and to see if might be a possibility. Plugged in but left out of throttle body and it idled, although high. Never had a code but may be part of my issue.

Author:	davidg91 [ Tue Dec 24, 2024 1:11 am ]
Post subject:	Re: Cranks but only starts with accelerator pedal depressed
CFAARON05 wrote: New to forum got an 05 KJ that will crank with key an attempt to start but then won't. If you plant accelerator to the floor will start but runs rough and feathering throttle will keep going but it dies if you let off throttle the may or may not start the same way. Things I've checked: Spark-all coils are providing spark checked with plugs saw spark on all with my own eyes Injectors-Ohms are all 11.3 except one is 16, all are receiving power when back probed(have not checked with noid light when running) Fuel pressure-checked with gage primes to 50 and holds when starting and when i get it to run as described before Idle air control-removed and valve moves freely with little to no effort(unplugged and no change but will record code that it is not present),(havent checked any other way) Tps-getting power will register on multimeter through full range Replaced crank and cam position sensors with used sensors but was doing with old sensors already Bought as a project that failed after shutting off in a parkinglot then began cranking as described. Key on key off X3 will show codes on dash display. Pcm cleared daily due to interior lights are always on even after changing multiswitch on column, so cant leave battery attached. Any great KJ techs that can give me some next step ideas to check? I see the same thing sometimes, never when the engine is completely cold, and not when turning it off and immediately back on, sometimes several times a day (frustrating!) and sometimes not for months at a time. When it happens, the engine has been off for 5-30 minutes. I too did a fuel pressure check which held constant running and after turning it off as documented. The issue persisted past a new engine.

Author:	davidg91 [ Thu Mar 06, 2025 9:54 pm ]
Post subject:	Re: Cranks but only starts with accelerator pedal depressed
After several years, and several times last week, of this sporadic crank but failure to start issue, even after a new Jasper engine, I replaced the cranskshaft and camshaft sensors, Delphi brand. Replacing them was not too difficult. We'll see whether that fixes the issue.

Author:	davidg91 [ Sat Mar 29, 2025 10:46 pm ]
Post subject:	Re: Cranks but only starts with accelerator pedal depressed
There are no codes displayed with the key cycling nor saved for a later scanner, but are there any real-time scanners that I could keep in the vehicle and connect when/if it happens again that might show any useful real time data?

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Cranks but only starts with accelerator pedal depressed http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=3&t=92944	Page 1 of 1

Author:	davidg91 [ Fri Aug 22, 2025 5:52 pm ]
Post subject:	Re: Cranks but only starts with accelerator pedal depressed
I still sporadically see the crank no start issue on a warm engine even with the new sensors. The Delphi crankshaft position sensor failed after a few months causing stalls, check engine light and threw codes. I put back in the original and it works again (no check engine).

Author:	WWDiesel [ Fri Aug 22, 2025 11:44 pm ]
Post subject:	Re: Cranks but only starts with accelerator pedal depressed
I would recommend replacing the Crankshaft Position Sensor and the Camshaft Position Sensor with new OEM ones. Your used CPS could still be bad and failing when it heats up. Crankshaft position sensor PN: 56041479AC Camshaft position sensor PN: 56041584AF

Author:	davidg91 [ Sat Aug 23, 2025 9:10 am ]
Post subject:	Re: Cranks but only starts with accelerator pedal depressed
I looked for the OEM ones, but Mopar 56041479AC Sensor-Crankshaft Position at least seems to be discontinued and not available anywhere. I do see Mopar 56041584AF Sensor-CAMSHAFT at moparpartsgiant. It's $120 compared to the $20 aftermarket ones, but worth it if it fixed the intermittent issue. I bought the Delphi, the most expensive of the after market ones, hoping it would be the best quality but that did not work out. Later, "someone" said that NTK sensors were used by Dodge. I don't know.

Author:	WWDiesel [ Sat Aug 23, 2025 2:16 pm ]
Post subject:	Re: Cranks but only starts with accelerator pedal depressed
NTK 73211 EH0395 Crankshaft Position Sensor https://www1.rockauto.com/en/parts/ntk, ... ensor,7196

Author:	davidg91 [ Sat Aug 23, 2025 5:25 pm ]
Post subject:	Re: Cranks but only starts with accelerator pedal depressed
There are many different experiences people have with different brand sensors. Here's just one thread: https://wranglertjforum.com/threads/ntk-sensors-vs-mopar.39102/

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