Fuel pump won't shut off, Jeep won't start. - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 05-03-2014, 06:02 PM   #1
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
Fuel pump won't shut off, Jeep won't start.

Jeep died on my way home the other night. 1989, 2.5L, standard.

Didn't hear the fuel pump prime, so I assumed it was that, after swapping the relay's I had replaced recently, to make sure it wasnt that.

I replaced the fuel pump, but it still didn't prime. I cut out what seemed like a bad fusible link, which turned out to be good. it was a terminal near it.

So I went to start it, still nothing. Swapped relay's and it finally started pumping!!

but then it didn't stop... I put more gas into it. Still didn't stop. I even went as far as to swap my old fuel pump back into the tank. now that one isnt stopping either!

I know my automatic shutoff relay is bad, but everything else seems to be fine. It just won't build any pressure. Whenever I go to try and start the thing it just cranks.

TwoPointFiveLiter is offline   Quote
Old 05-03-2014, 07:39 PM   #2
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
replaced both relays, nothing changed.

I replaced the crank position sensor about 2 years ago.

TwoPointFiveLiter is offline   Quote
Old 05-03-2014, 07:58 PM   #3
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
Could a fuel pressure regulator stuck open be causing my Jeep to not start? It would make sense that it would keep it running, constantly trying to build pressure, right? But would that really stop it from firing?

Im stumped.
TwoPointFiveLiter is offline   Quote
Old 05-04-2014, 08:46 AM   #4
Jeeper
 
Defcon 1's Avatar
 
Join Date: Jun 2012
Location: South New Jersey
Posts: 830
Can you get a pressure reading at the fuel rail? You can rent a fuel-pressure gauge from Autozone. Hook that up and see what you have at the rail. It should prime up to around 30 psi and then stop. I don't know if the ASD waits to get to a certain psi and then shuts off, so there could be a clog somewhere in the system or the FPR is stuck open like you said.

If they ASD doesn't require a certain psi I would think that there is something electrically going on to keep the pump running continuously. I had installed a brand new fuel-pump relay and the relay turned out to be bad, so it kept my pump running continuously but the Jeep would fire. Also, can you get the Jeep to fire with an Ether shot down the TB? Maybe you have an ignition problem going on at the same time. First try to confirm that you have the correct psi getting to the fuel rail, it'll eliminate the regulator / a clog / ignition from being the issue.
Defcon 1 is offline   Quote
Old 05-04-2014, 07:47 PM   #5
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
Hey, I was looking at some of your topics earlier trying to figure this out.

but yeah, I bought two new relays, those arent the problem. and it's an 89, so there's no fuel rail, it's single point injection.

I havent tried to get a reading on the pressure yet, im gonna do that tomorrow. But my father today tried starting it by putting some gas directly in and it wouldnt start. So it looks like I also have no spark...

Bad ECU? Bad crank position sensor?
TwoPointFiveLiter is offline   Quote
Old 05-04-2014, 07:48 PM   #6
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
Im thinking it might be the ECU, even though it's only two years old. Cause I remember when it was in the process of dying, the voltage gauge was freaking out. It would go from 0 to normal level and back down very rapidly, over and over again.
TwoPointFiveLiter is offline   Quote
Old 05-04-2014, 10:17 PM   #7
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
So if my fuel pump wasnt kicking on, I would say it was the Crank position sensor. Because I've read that that stops the spark and stops the injectors.

However, my fuel pump is constantly pumping.

Maybe a mix of a bad fuel pressure regulator and something causing it to not get spark?

bahh...I just want my Jeep back.
TwoPointFiveLiter is offline   Quote
Old 05-05-2014, 09:26 AM   #8
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
I doubt it's the CPS, because I checked it with a meter. It's supposed to have 200 +- 75 ohms HOT. I checked COLD, and it had ~225. Even though I didnt check it when the engine was hot, because I can't, it's still in the normal range.

but then again, I read it's a fairly common problem. and it can cause the voltage gauge to not display properly, which it's fine at the moment, but when it was dieing it wasnt. My fuel pump is also acting odd, and it isnt getting spark at the plugs.

it might be a mixture of issues too. The act of something going bad caused my fuel pressure regulator to get stuck open?

Im gonna check for fuel pressure when I get home tonight. Is there any way to adjust the fuel pressure regulator? or do I have to just buy a new one?
TwoPointFiveLiter is offline   Quote
Old 05-05-2014, 08:37 PM   #9
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
The stupid fitting I had to test my fuel pressure was hitting when I tried to screw it in, so I have to buy a new one before I can test tomorrow.

Im also gonna pick up a CPS and try it out and at least rule it out as a possibility.
TwoPointFiveLiter is offline   Quote
Old 05-06-2014, 09:04 AM   #10
Jeeper
 
peety's Avatar
 
Join Date: Feb 2013
Location: Almost a PINEY...
Posts: 225
The CPS should not have anything to do with it, that is an output sensor that tells the ECU to fire the coil and injector...
It sounds like either the ECU or Ignition Switch. just above the relays are two test connectors, you want to look at the PINK wire, 12v switched from the ECU, it should gl dead after the Ign is turned off. This powers a ton of stuff on the engine. I will check my refference materials when I get home.
__________________
Patience and perseverance have a magical affect before which difficulties disappear and obstacles vanish.

John Quincy Adams
peety is offline   Quote
Old 05-06-2014, 07:46 PM   #11
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
I ended up using a Diagnostic/troubleshooting flowchart, it pretty much immediately brought me to "replace ECU and restart the test".

Took out the ECU, popper her open, and sure enough, one of the pieces is all melted.

So on my ride home, I had a melted wire going to my fusible link, blew my relay, and damaged my ECU. Causing no spark, and no fuel pressure.

But I got the new ECU ordered, hopefully the thing fires right up.
TwoPointFiveLiter is offline   Quote
Old 05-06-2014, 07:46 PM   #12
Jeeper
 
TwoPointFiveLiter's Avatar
 
Join Date: Feb 2012
Location: Central Massachusetts
Posts: 65
Thanks for the help too, Peety. I wish I saw your post before I picked the CPS up this morning. But whatever, I got a good backup now.
TwoPointFiveLiter is offline   Quote
Old 05-07-2014, 11:34 AM   #13
Jeeper
 
peety's Avatar
 
Join Date: Feb 2013
Location: Almost a PINEY...
Posts: 225
I did an external work around on mine. I added a relay powered and switched by the YELLOW wire coming from the Ignition switch and plugged the PINK in as the output to feed the components on the engine.
Glad you have it sorted.
P

__________________
Patience and perseverance have a magical affect before which difficulties disappear and obstacles vanish.

John Quincy Adams
peety is offline   Quote
Reply

Tags
fuel , fuel pump , relay , shutoff , wont start

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 12:40 PM.


User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC