Hard start, changed fuel pump, still hard start - JeepForum.com
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post #1 of 21 Old 09-28-2015, 06:04 PM Thread Starter
gaddman
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Hard start, changed fuel pump, still hard start

Hello everyone, I'm about to lose my mind on this heep. Lately I've been having trouble getting it to start after sitting overnight. After reading many posts on here I decided to change out the entire fuel pump unit. I dropped the tank, put in a new fuel pump (Precision from O'Riellys) and then filled up the tank. Same issue! Is it possible that I got a bad pump? I have pressure at the rail when I depress the valve but it's not a lot. If I cycle the key 6-8 times and let the key sit on for a few seconds, then it'll it start and once it's going and I shut it off, it'll crank back up no problem which is what makes me think that I possibly got a bad pump. Is there anything that I'm missing to help diagnose why it's still not starting?

Any help would be appreciated.

Thanks,
Alan
97 Sahara

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post #2 of 21 Old 09-28-2015, 06:09 PM
TJ4Jim
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If you have a test port on your fuel rail I would say it's time to get a gauge reading to be sure.

If you come to a fork in the road take it.
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post #3 of 21 Old 09-28-2015, 06:18 PM
Jerry Bransford
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That still sounds like a bad fuel pump, which is why I only recommend Bosch or Mopar fuel pumps. Store brand pumps are not worth the effort to install, few last more than a year or two. An off-brand (Spectra) fuel pump I installed 3-4 years ago lasted just over 12 months, just past its warranty.

When you have a choice, buy American made.
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post #4 of 21 Old 09-28-2015, 06:19 PM Thread Starter
gaddman
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Yea, I've got to find a place that has a gauge that I can rent/borrow. I went to O'Reilly's and Advance and neither one of them had a guage. I'll have to check Auto Zone tomorrow.
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post #5 of 21 Old 09-28-2015, 06:21 PM Thread Starter
gaddman
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Quote:
Originally Posted by Jerry Bransford View Post
That still sounds like a bad fuel pump, which is why I only recommend Bosch or Mopar fuel pumps. Store brand pumps are not worth the effort to install, few last more than a year or two. An off-brand (Spectra) fuel pump I installed 3-4 years ago lasted just over 12 months, just past its warranty.
I hear ya Jerry. I didn't see your posts on them until tonight. If I had known, the extra $120 for Mopar would have been worth it. Good thing is that the one I have has a lifetime warranty. Bad thing is that I have to take the thing back out.
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post #6 of 21 Old 09-28-2015, 07:33 PM
Andy5150
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My jeep would crank for a long time before starting, and I cured it by cleaning the throttle body.
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post #7 of 21 Old 09-28-2015, 07:43 PM
Jerry Bransford
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Quote:
Originally Posted by Andy5150 View Post
My jeep would crank for a long time before starting, and I cured it by cleaning the throttle body.
The below symptom he described confirms it's from a leaky fuel pump.

Quote:
Originally Posted by gaddman View Post
If I cycle the key 6-8 times and let the key sit on for a few seconds, then it'll it start and once it's going and I shut it off, it'll crank back up no problem which is what makes me think that I possibly got a bad pump.

When you have a choice, buy American made.
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post #8 of 21 Old 09-28-2015, 07:52 PM Thread Starter
gaddman
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Just for good measure, I did clean the throttle body yesterday. Really didn't do anything. I was also trying to figure out why I have a whistling sound when I hit the gas hard and was checking the throttle body gasket. Still haven't figure out what that is either.
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post #9 of 21 Old 10-02-2015, 03:55 PM Thread Starter
gaddman
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Just a quick update. I measured the pressure with a gauge and was getting 48-50 psi while running. I turned the Jeep off and waited for the pressure to drop, which it did but it took hours. After 20 minutes it was still sitting at 42 psi, it took 3 hours for it to drop to 30 psi. This is all in line with the FSM. Here's my next question, could this be something electrical? The reason I ask is that when I first turn the key on, the fuel gauge doesn't move, neither does the battery gauge. I have to cycle the key 2-4 times before either gauge will register and then cycle it another 3-4 times before I can attempt to start it. I've took a couple of videos and here are the links. The first video is what I normally go through to start on a cold engine. The second video is still cold but it takes a couple of cycles to start. After letting it run for a couple of minutes, it started every time after that without a problem. Am I just trying to talk myself out of having to take out that stupid fuel pump again or could this be something with the PCM or something else? Any help would be greatly appreciated.

Video 1 http://drive.google.com/open?id=0B5Z...2xObDlISVVVcFk

Video 2 http://drive.google.com/open?id=0B5Z...mNzMmtxeHgzczA

Thanks
Alan
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post #10 of 21 Old 10-02-2015, 09:52 PM
crazyj23
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My jeep has the same symptoms as yours. I also changed the fuel pump with the same results. I've kind of given up because I don't want to waste money. After reading a lot about the hard to start issues, it's lead me to the crank position sensor. I will be changing that next. I'll post again about how it goes.
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post #11 of 21 Old 10-03-2015, 10:24 AM Thread Starter
gaddman
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So this morning I went to the garage and put the fuel pressure gauge on the rail again. There was zero pressure reading as I knew there would be from sitting overnight. I turned the key on and the fuel gauge and battery gauge didn't move once again but the pressure on the rail jumped up to 50 psi immediately. I didn't do anything for about 30 seconds and then the gauges both moved. I decided to try cranking it up and it started on the first try. I'm very confused at this point. So I've left the test gauge attached and have been recording the readings periodically. Here's the photos at 3 min and 50 min so far. I'll go back out and check it again at 1.5 hrs. I really don't know where else to go and the FSM hasn't really been a help. I did to a test of the instrument cluster and it was exactly in line with the FSM checklist. Please, if anyone knows what this could be, it would really be appreciated.

The top pic is at 3 min after shutting the engine off and the second pic is at 50 min.
Attached Thumbnails
jeep fuel 3 min.jpg   jeep fuel 50 min.jpg  
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post #12 of 21 Old 10-03-2015, 10:49 AM Thread Starter
gaddman
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Fuel pressure at 2 hours.
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post #13 of 21 Old 10-03-2015, 12:38 PM
crazyj23
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I've read about leaking injectors causing this issue as well. What engine codes are you getting?
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post #14 of 21 Old 10-03-2015, 12:40 PM Thread Starter
gaddman
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Quote:
Originally Posted by crazyj23 View Post
I've read about leaking injectors causing this issue as well. What engine codes are you getting?
I'm not getting any codes.
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post #15 of 21 Old 10-03-2015, 01:01 PM Thread Starter
gaddman
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Just checked it all again. Depressurized the fuel system, turned the key, pressure only went up to about 10 psi and it took 6 more on/off cycles with the key before it got up to 42 psi. This thing is just so inconsistent that I'm going to take the fuel pump back out and go get a new one. We'll see what happens.

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