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Old 06-10-2013, 09:51 PM   #1
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Confused, Leaky Injector?

Ok, so I got around to putting the new Bosch fuel pump module in my '03 Wrangler X 4.0 after getting annoyed with the "hard start" that is common among jeeps, while also hoping to correct some other performance issues (hesitation, rough idle.)

Everything went smooth with the install, and before the first initial start I turned the key to the on position for 10 seconds or so to allow the system to build pressure. When I started it, it cranked for about 4-5 seconds and then fired up. This didn't come as too much of a surprise as the system had been relieved of it's pressure.

However, what has come as a surprise, is that since installing the brand new pump, every cold start takes longer than seems normal. Is it possible that I got a brand new pump and it has a faulty drain-back valve? Did I screw it up? Or should I start looking at the possibility of leaky injectors? Or better yet, is there something I'm overlooking or something I can do to narrow this down? Crank position sensor? All comments, guidance and suggestions are appreciated!

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Old 06-11-2013, 01:17 AM   #2
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Does the motor run rough for a minute then smooth out after a cold start?

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Old 06-11-2013, 05:57 AM   #3
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Not really. It runs well while driving, but still has the rough idle.
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Old 06-12-2013, 03:34 PM   #4
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UPDATE: Let the jeep sit overnight. Went out this morning and pushed the center of the port on the injector rail and no fuel spit out at me at all. So again it's an issue with pressure at the rail. But is it the check valve in the brand new pump or a leaky injector?
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Old 06-12-2013, 03:39 PM   #5
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Did you replace the entire fuel pump module or just the pump itself? It's my understanding that the check valve isn't in the pump itself.
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Old 06-12-2013, 03:44 PM   #6
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Entire module assembly, which includes the pump, sending unit and regulator. Sorry I should've mentioned it.
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Old 06-12-2013, 07:00 PM   #7
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Got out of work tonight and let the pump prime for 5 seconds before trying to start the jeep. Still started hard, which I find odd. Got home and left the jeep running to do a quick injector check(held a screwdriver on the injector and put my ear on the other end.) All sounded to be working correctly, but that does not rule out a leaky injector after the engine shuts down. I'm really at a loss here.
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Old 06-13-2013, 09:41 AM   #8
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So I drove the jeep for about 45 minutes this morning and then let it sit for 30 minutes before going to work. Got in to start it up and all it did was crank and crank. The pressure in the system was gone after 30 minutes? That seems really quick. Started right up during second attempt. Anyone have any ideas?
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Old 06-13-2013, 12:40 PM   #9
Knows a couple things...

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Odds are very good that you got a defective (leaky) fuel pump assembly. That exact same thing happened to me & replacing it again cured the issue. It took me months before finally convincing myself that I had exhausted all other possibilities including leaky fuel injectors.
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Old 06-13-2013, 01:16 PM   #10
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Odds are very good that you got a defective (leaky) fuel pump assembly. That exact same thing happened to me & replacing it again cured the issue. It took me months before finally convincing myself that I had exhausted all other possibilities including leaky fuel injectors.
That's what I was afraid of. I got the pump assembly from Amazon brand new. I don't know if I can send it back to them for a new one now that it's been installed and used technically. Which means I'll have to go through Bosch. Lovely.
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Old 06-13-2013, 01:18 PM   #11
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Unfortunately most electrical parts don't have a warranty once installed. I wouldn't hold my breath waiting for a free replacement under warranty.
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Old 06-13-2013, 01:33 PM   #12
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Unfortunately most electrical parts don't have a warranty once installed. I wouldn't hold my breath waiting for a free replacement under warranty.
So what's the point of the warranty? I guess at that point I'll just get a new regulator instead of the whole pump assembly.
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Old 06-13-2013, 04:28 PM   #13
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Amazon is shipping a new replacement at no charge. It'll be here tomorrow and I have 30 days to send back the defective unit. No charge for shipping or anything. Best case scenario?
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Old 06-13-2013, 04:52 PM   #14
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Amazon is shipping a new replacement at no charge. It'll be here tomorrow and I have 30 days to send back the defective unit. No charge for shipping or anything. Best case scenario?
Outstanding!

Best case... It works
Worst case.... It doesn't.

There was another member that went through about 4 or 5 before he got one that actually worked. Good luck.
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Old 06-13-2013, 05:03 PM   #15
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Outstanding!

Best case... It works
Worst case.... It doesn't.

There was another member that went through about 4 or 5 before he got one that actually worked. Good luck.
Hopefully it'll only take 2 for me. Fingers crossed. I'll update you after the install this weekend.
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Old 06-17-2013, 01:51 PM   #16
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So I'll try to give everyone a brief update. I dropped the tank again yesterday and found gas around the area of the locknut. So either the new gasket that came with the pump was bad or the locknut wasn't tight. I have a hard time believing the locknut was loose, but hey I'm not perfect. Anyways, the new pump and gasket are in, and it starts stronger than ever. It did not, however, correct the hesitation under load immediately after shifting or the rough idle.

On a separate note, Amazon told me to ship the used pump back to them, knowing it was soaked in gas. I let the pump air out and then repackaged it perfectly. I took it to UPS and the refused to ship it because it was soaked in gas, even though Amazon is the one who gave me the prepaid shipping label. I called Amazon after going to UPS and they told me to throw it out and I wouldn't be charged for the replacement. I'll be watching my statement closely...
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Old 06-18-2013, 02:41 AM   #17
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So I'll try to give everyone a brief update. I dropped the tank again yesterday and found gas around the area of the locknut. So either the new gasket that came with the pump was bad or the locknut wasn't tight. I have a hard time believing the locknut was loose, but hey I'm not perfect. Anyways, the new pump and gasket are in, and it starts stronger than ever. It did not, however, correct the hesitation under load immediately after shifting or the rough idle.

On a separate note, Amazon told me to ship the used pump back to them, knowing it was soaked in gas. I let the pump air out and then repackaged it perfectly. I took it to UPS and the refused to ship it because it was soaked in gas, even though Amazon is the one who gave me the prepaid shipping label. I called Amazon after going to UPS and they told me to throw it out and I wouldn't be charged for the replacement. I'll be watching my statement closely...
Amazon is really good about that. You shouldn't have any problems with them.

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