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Old 04-01-2016, 07:17 PM
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HELP: Intermittent Starting Problems

I have a 2004 LJ that has had the following starting problems:

Over a month ago with random stalling problems, replaced the fuel pump, crankshaft position sensor with an AFTERMARKET unit and replaced the camshaft position sensor with an AFTERMARKET unit. Stalling continued until I replaced the camshaft position sensor with an OEM unit.

A month goes by and everything is great.

Two weeks ago, the following symptoms appear:

Turn the key, just cranks over and over.
Turn the key again, and it starts fine.

One week ago:

Needs three tries to start

This week:

Needs six tries to start - not sure it will again!

Should I replace the crankshaft sensor with an OEM unit, or do you think I have ECM problems?

BB

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Old 04-01-2016, 07:35 PM   #2
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Fuel pump check valve or leaky injector

Try this cycle key on off on off on off on off each time pausing 3-5 seconds in on position before attempting start

Also

Quit throwing random parts at God jeep

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Old 04-01-2016, 09:48 PM
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Ha! You are correct that I am throwing parts at it. Actually two mechanics have thrown parts at it because it has not thrown any codes. The one that replaced the fuel pump said there was very low pressure, so that was his reasoning. Ran beautifully for a week, then stalled again randomly. That's when the dealer replaced the camshaft sensor - and voila! No more stalling!

Now the starting problem plaques me. And oh, boy, do mechanics love it when you tell them what to do! Tomorrow I will try the cycling approach. What will that tell me?

This is my DD so that's why I'm desperate.

Thanks!
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Old 04-01-2016, 10:23 PM   #4
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When you cycle key you get repeat priming runs of fuel pump which is needed if you have a leaky check valve in pressure regulator in tank or a leaky injector pissing away rail pressure

So if cycling makes it start normally you have identified your issue
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Old 04-01-2016, 11:09 PM
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If the mechanic replaced my fuel pump, would that typically include the fuel pump check valve?
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Old 04-01-2016, 11:15 PM   #6
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Yes but not all new parts are good parts hence throwing on new parts just confounds finding problems as you can create problems where none previously existed
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Old 04-02-2016, 02:58 PM
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Today's Symptoms

Quote:
Originally Posted by Digger84 View Post
Yes but not all new parts are good parts hence throwing on new parts just confounds finding problems as you can create problems where none previously existed
Today it started up on the second try. I drove about ten minutes to the store. Came out and it started again on the second try - BUT idled a bit rough. It smoothed out after a minute, then I started driving - and....

....got a P0171 CEL code.

It has to go to a mechanic because I have no clue. Any thoughts?

BB
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Old 04-02-2016, 03:26 PM   #8
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Suspect your new fuel pump

What is rail pressure?

Sound familiar https://www.wranglerforum.com/f210/p0.../786385?page=1
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Old 04-02-2016, 04:49 PM
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Funny story - Just sold some Rubicon rims to a local guy. He tells me he has been a Jeep dealer mechanic for six years, so I tell him my story. Given the fuel pump is new, he says the stock Siemans injector suck, and thinks that may be the problem. He recommends Bosch 4-hole injectors. He may even do the work on the side!

So, I start to drive away, and after the third try it catches, and runs like one cylinder isn't firing for a minute, then smooths out. Maybe a lousy injector...
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Old 04-02-2016, 05:18 PM   #10
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Please attempt to identify a problem rather than guessing and throwing parts at it

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