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Topic Review (Newest First)
03-21-2011 01:18 PM
Peepers
Quote:
Originally Posted by KP Texan View Post
An excerpt from the FSM reads: "The fuel pump is energized through the fuel pump relay by the PCM. The fuel pump will operate for approximately three seconds unless the engine is operating or the starter motor is engaged".....so basically that logic is controlled by the PCM, assuming that the contacts are opening/closing correctly within the ignition switch.

-Wes
This is what I was assuming it was a contact switch, when the starter kicked on it turned the fuel pump on. I will try the relay swap tonight, although I feel like you where if it was the relay then it might not work at all.

This also goes back to the PCM, which could be the problem as well, something about capacitors or something in a higher post.

My main concern at the moment it getting the fuel pump retaining nut back on properly and stop my CEL "Large Evap Leak". after that I'll fiddle with any inconsistanties...
03-21-2011 01:08 PM
KP Texan
Quote:
Originally Posted by Peepers View Post
Yes I am certain It is not kicking on when the key is in the run position. I had a leak in the line from the pump to the frame rail I was trying to diagnose. they key was in the run position for about a minute with no leaks, and the second the engine started cranking from turning the key, fuel started squirting out every where, and slowly died off after the engine was shut off as the fuel pressure decreased.
An excerpt from the FSM regarding key-on mode reads: "The fuel pump is energized through the fuel pump relay by the PCM. The fuel pump will operate for approximately three seconds unless the engine is operating or the starter motor is engaged".....so basically that logic is controlled by the PCM, assuming that the contacts are opening/closing correctly within the ignition switch.

Things to check first would probably be fuel pump relay and ignition switch. I'm leaning more towards the ignition switch because if it were a relay then it probably wouldn't run at all. The relay is easy enough to check by swapping with your horn relay but the ignition switch would be difficult to test. My ignition switch problem manifested itself as something that really seemed different because my start problem was completely intermittent. For $35 it may be worth it to swap in an ignition switch before doing anything with the PCM.

-Wes
03-21-2011 12:33 PM
Peepers
Quote:
Originally Posted by KP Texan View Post
Are you sure it's not priming when you turn the key to run? My pump is really quiet and hard to hear over that annoying beep when you turn the key on. The best way to tell is put a gauge on the fuel rail; you should see the pressure jump up as soon as you turn the key. Or, you could have someone put their head down near the tank as you turn the key on. If it doesn't run, something is not working right.

As far as the ring goes, you'll notice that the pump module is spring loaded and you can push it down into the tank. I first put my new seal on the tank and then pressed the module down and it pretty much stayed by itself...just make sure the lip on the module is seated all the way down on your tank seal before turning the plastic retaining ring. I also cleaned up the plastic threads and applied a bit of white lithium grease so that the ring wouldn't grab so badly. Turn the ring counterclockwise until you feel it click past the start of the tank threads, and then proceed to turn it clockwise to tighten by hand. I cranked down on it as hard as I could by hand and then I lightly tapped those plastic ridges on top of the ring horizontally with a big flathead screwdriver and hammer in the clockwise direction. You obviously can't go wailing on the plastic ring so be careful, but you can get it to tighten up a bit more and seal completely.

Hope this helps,

Wes
Yes I am certain It is not kicking on when the key is in the run position. I had a leak in the line from the pump to the frame rail I was trying to diagnose. they key was in the run position for about a minute with no leaks, and the second the engine started cranking from turning the key, fuel started squirting out every where, and slowly died off after the engine was shut off as the fuel pressure decreased.

I know my original problem was the seal there, putting the original back in, it would not stay "pressed in" like you mentioned. I replaced the seal and you could push the pump in and get it to stay. I will have to try lubing the threads when I put it back together this time. I was using a strap wrench and the nut would not budge. I even picked up a new mopar nut in hopes that my original might have been damaged, with no luck though.
03-21-2011 12:13 PM
KP Texan
Quote:
Originally Posted by Peepers View Post
Well this seems like the place to post my quirory. Two things, one from what I read here, and one seeing as you have done what I'm about to do:

1) on my 98, the fuel pump won't prime in the ON position, but once you start to crank the engine over it pumps up right away with no issues. is this normal, or something I should be concerned with?

2) I've been trying to get the retaining nut for the fuel pump to sit flat on the tank. one side is always higher than the other, and I currently am seeing a fuel leak from around the pump opening. I bought a new seal and nut, but it doesn not want to thread onto the tank. any hints or suggestions to help put it on?
Are you sure it's not priming when you turn the key to run? My pump is really quiet and hard to hear over that annoying beep when you turn the key on. The best way to tell is put a gauge on the fuel rail; you should see the pressure jump up as soon as you turn the key. Or, you could have someone put their head down near the tank as you turn the key on. If it doesn't run, something is not working right.

As far as the ring goes, you'll notice that the pump module is spring loaded and you can push it down into the tank. I first put my new seal on the tank and then pressed the module down and it pretty much stayed by itself...just make sure the lip on the module is seated all the way down on your tank seal before turning the plastic retaining ring. I also cleaned up the plastic threads and applied a bit of white lithium grease so that the ring wouldn't grab so badly. Turn the ring counterclockwise until you feel it click past the start of the tank threads, and then proceed to turn it clockwise to tighten by hand. I cranked down on it as hard as I could by hand and then I lightly tapped those plastic ridges on top of the ring horizontally with a big flathead screwdriver and hammer in the clockwise direction. You obviously can't go wailing on the plastic ring so be careful, but you can get it to tighten up a bit more and seal completely.

Hope this helps,

Wes
03-21-2011 11:54 AM
Peepers Well this seems like the place to post my quirory. Two things, one from what I read here, and one seeing as you have done what I'm about to do:

1) on my 98, the fuel pump won't prime in the ON position, but once you start to crank the engine over it pumps up right away with no issues. is this normal, or something I should be concerned with?

2) I've been trying to get the retaining nut for the fuel pump to sit flat on the tank. one side is always higher than the other, and I currently am seeing a fuel leak from around the pump opening. I bought a new seal and nut, but it doesn not want to thread onto the tank. any hints or suggestions to help put it on?
03-21-2011 11:33 AM
KP Texan
Quote:
Originally Posted by TexasT View Post
I love going to the National Seashore and little shell to Mansfield cut. Haven't been down there in two years...I need to make the trip soon. I'm just out of Kerrville so use the jeep on the hills usually.
Well, in my opinion, the Kerrville/Fredericksberg is about the most beautiful place you can be in Texas. I'd love to live in the Hill Country once I retire but, being 28 years old and in the maritime industry, that's not really an option for me at this point.

-Wes
03-20-2011 11:24 PM
TexasT I love going to the National Seashore and little shell to Mansfield cut. Haven't been down there in two years...I need to make the trip soon. I'm just out of Kerrville so use the jeep on the hills usually.
03-20-2011 11:02 PM
KP Texan
Quote:
Originally Posted by TexasT View Post
Excellent...I've been watching your thread and the good info. Glad it's fixed. Now enjoy the beach. Galveston?
Mostly Port A but really any of the various beaches around Portland, TX, which is where I live.

Thanks,

Wes
03-20-2011 10:56 PM
TexasT Excellent...I've been watching your thread and the good info. Glad it's fixed. Now enjoy the beach. Galveston?
03-20-2011 09:54 PM
rgaba awesome! Add that to the books! I know how relieved you must feel.
03-20-2011 08:10 PM
KP Texan IT'S FIXED!!!! I'm so happy right now!

I went to Oreilly's today and picked up three things: Crank position sensor, ignition switch, and turn signal switch. I figured than since I would have the steering column shroud off already for the ignition switch, I would go ahead and tackle my tj's problem about the turn signal not turning off on a left turn. Although more people seem to have problems with their CPS, I decided to do the ignition switch/turn signal first. I knew my ignition switch was a bit iffy already because I could turn off my accessories while the engine was still running...it also just didn't have a good positive feel to it when turning the key. I was skeptical that the ignition switch would fix it but I was completely wrong!

My Jeep starts on every turn of the key now, rather than being intermittent. As stated, I did have a problem with the check valve on my fuel pump too so I guess those two problems combined made my situation even worse. Oreilly's was also very good about taking my $70 uninstalled CPS back as a return...I didn't think they would do it so I was surprised at that. The ignition switch was only $35 and a piece of cake to install. The only problem I ran into was the need for a security T10 security torx but I was able to find a whole set of those for cheap at Oreilly's too. Hopefully my findings help someone troubleshoot their TJ in the future!

-Wes
03-20-2011 12:53 AM
KP Texan My next two tries will be the cps and the ignition switch. I plan on changing the cps tomorrow.

-Wes
03-19-2011 11:47 PM
rgaba
Quote:
Originally Posted by KP Texan View Post
Yes, the pump primes every time I turn the key.

Thanks,

Wes
I'm not sure what else it could be? Replacing the pump assy gave you new primary and secondary check valves. You've already verified this with a pressure check. Have you checked the pressure after some time sitting? , right before cranking? You may have received a defective unit? Proper tune up and rail pressure should start that thing right up. The only other thing I could think of is the cps. Maybe the seasoned jeepers in here can chime in. The cps was the culprit in my bmw 535i for intermittent starting problems. I was able to test it with a multimeter.
03-19-2011 11:27 PM
KP Texan Yes, the pump primes every time I turn the key.

Thanks,

Wes
03-19-2011 11:17 PM
rgaba
Quote:
Originally Posted by KP Texan View Post
I went to the dealer and bought a new seal for peace of mind; it was only $9.50. I also cleaned all the rust under there and rewired my tow wiring.

The good news: my tj now holds fuel pressure at the rail after I shut it off (verified with gauge). It actually seems to idle and run better.

The bad news; I've still got an intermittent start issue. I have to do several short starts and then it will fire off like nothing is wrong.

What could this be????!!!!! Please help!! My wife is pissed off at all the time and money I spent working on it today, especially since I assured her this was the starting issue .

Thanks so much,

Wes
My friend's 94 4cyl YJ also had a starting issue but it wasn't like my pump,check valve problem. It was his ECM. He brought his ECM to me to install new capacitors. He told me he found out on the forums that when the capacitors are going bad, the ignition had to be cycled several times to build up enough charge on the caps to power the fuel pump. The new caps installed in the ECM fixed his problem. I don't know if this fix applies to 4.0's ECM but can you hear your fuel pump prime when you put the ignition in position 2? Dont crank, just listen for the pump.
03-19-2011 10:51 PM
KP Texan I went to the dealer and bought a new seal for peace of mind; it was only $9.50. I also cleaned all the rust under there and rewired my tow wiring.

The good news: my tj now holds fuel pressure at the rail after I shut it off (verified with gauge). It actually seems to idle and run better.

The bad news; I've still got an intermittent start issue. I have to do several short starts and then it will fire off like nothing is wrong.

What could this be????!!!!! Please help!! My wife is pissed off at all the time and money I spent working on it today, especially since I assured her this was the starting issue .

Thanks so much,

Wes
03-19-2011 10:23 PM
rgaba
Quote:
Originally Posted by KP Texan View Post
On closer inspection, this tank seal looks like new. It's flexible and there are no cracks, damage, or wear marks. Im thinking it will work fine but I don't want to have to drop my tank again.

Thanks,

Wed
I also replaced my pump/sending unit assembly because of starting issues. (2 to 3 long cranks before it would start). I found one at a salvage yard for $50. My seal was also in good shape and I ended up reusing it. It's been several months now and no evap emission cel codes. I think you'll be fine with the old one. Just make sure all is clean when reassembling. It starts right up now. My TJ actually sat for a week and a half when I was out of town and I was anxious to see how it would start after sitting that long and it started right up. Good luck to you with the repair.
03-19-2011 09:53 PM
pappaw I just put one in my 99 this weekend. I purchased an Airtex fuel module from my place of employment(Adavance Auto) and it came with a new gasket(seal).
03-19-2011 01:31 PM
KP Texan I'm think I'm just going to have them welded up on Monday .... By the time I screw around with jb welding and all that stuff, $100 doesn't sound that bad to have it fixed right. Besides, I want to get the tj up and running so I can hit the beach!

-Wes
03-19-2011 01:06 PM
99jeeper what ya decide to do with the tub holes?
03-19-2011 12:45 PM
KP Texan On closer inspection, this tank seal looks like new. It's flexible and there are no cracks, damage, or wear marks. Im thinking it will work fine but I don't want to have to drop my tank again.

Thanks,

Wed
03-19-2011 03:11 AM
KP Texan A few photos of the project:

I had over a half tank of fuel so I spent a bit of time siphoning... not really much fun.


At least I can now properly treat some of the rust on my skid plate. It's amazing how much crap the skid plate was holding; no wonder it was rusting from the inside!


The new module...see, no tank seal with it!!


-Wes
03-19-2011 01:57 AM
KP Texan
Fuel Pump Module Replacement...

Due to a starting issue I've been having with my '97 Sahara, I dropped my fuel tank this evening in order to replace the fuel pump module. I realize that the this starting issue has nothing to do with the sending unit but I was able to get a whole module for about the price of the pump alone at most places. When I opened the box up to my new Bosch fuel pump module, I realized that there is no seal for the top of the tank. It even states in the FSM that you must replace that seal whenever changing the pump. When any of you guys have changed out your pump or module, did yours come with that tank seal? My friend that owns the auto parts store is checking on it tomorrow but I was just wondering what your experiences were.

Thanks so much,

Wes

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