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Unread 10-17-2011, 01:41 PM   #1
smlein
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2004 TJ 6cyl, slow start when cold, please help

Looking for answers, any ideas are appreciated...

My 2004 TJ Sport has trouble starting when cold. It cranks a couple of times before turning over. The slow start can be avoided if I the key to ON a couple of times before I try to start.

After running for a bit, if i don't let it sit for too long, it starts up quick, no problems. It was throwing an engine light and a P0301 code.

Per previous research and advice, I just replaced the entire fuel pump assembly module (which I'm told includes the fuel pressure regulator, which would keep the fuel from draining back to the tank causing the slow start). then disconnected the battery for a bit to reset the code.

The jeep's running smoother (so there was probably a fuel pump problem too), but the slow start issue remains.

Anyone have an idea on what it could be? O2 sensor? the fuel pressure regulator on the fuel rod? spark plugs? Fuel injectors?

Thanks for the advice.

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Unread 10-17-2011, 01:53 PM   #2
flying_bosun
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How's the battery?
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Unread 10-17-2011, 06:02 PM   #3
smlein
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Battery

The battery is good. The battery was replaced within the last year. Both it and the alternator were tested first in this process, before we moved on to the fuel pump.
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Unread 10-17-2011, 06:54 PM   #4
jkp
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Sounds like it's losing fuel pressure. Does it have a valve on the fuel rail? If so, check the fuel pressure after it has been sitting to see if it leaked down.

Possible leaking injector.
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Unread 10-17-2011, 07:18 PM   #5
smlein
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Fuel Pressure

As far as we (my mechanic and I) can tell, there's no valve on the rail to check fuel pressure. There's a (2nd?) fuel pressure regulator on the rail that may need to be replaced.

But a leaking injector... that's a new theory. Will have to keep it in mind.

Checking the pressure is likely the next step. Anyone know where (if) there's a place to hookup a fuel pressure gauge in this vehicle?

From our research so far, it looks like to check the pressure, we'll need to create a connection in the line. That kinda sucks (which is why it hasn't been done yet).
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Unread 10-17-2011, 07:28 PM   #6
jkp
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Well, that does suck. I know my '92 has a schrader valve test point. Not sure if the '06 has it or not.

There is not a fuel pressure regulator on the rail. It is a "fuel damper", per the FSM, used to dampen the pulsations from the injectors firing.

This may be useful: http://www.jeep4x4center.com/jeep-se....swf#toolbar=0
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Unread 10-18-2011, 12:31 AM   #7
Rubi4MyMrs
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Since you were getting the P0301 (misfire #1 cylinder), code you may well have the #1 injector leaking down & causing the hard start. The other thing is are you sure the fp module (including the regulator) was replaced? If so then I'd bet it's the injector.

The factory tool for checking the pump pressure involves opening the line going to the rail & a hose with a "T" fitting for a gauge going between the line & rail.
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Unread 10-18-2011, 07:10 PM   #8
smlein
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JKP - Thanks for that link! Very cool info. Very helpful.

Rubi4MyMrs - We replaced the entire FP module, so that should be clear. Thanks for the injector idea. That's two in a row... going to have to look into that.
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Unread 10-20-2011, 10:13 PM   #9
smlein
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Random update: Still slow-starting, but the engine light is no longer on. /boggle
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