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ZJ In tank Fuel pump Bypass..Also known as SWAMPY BYPASS..


 
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swamp boy
Cherokee Muderator
Cherokee Muderator


Joined: 01 Jan 2004
Location: New Orleans LA.

PostPosted: Sat Jan 03, 2004 6:28 am    Post subject: ZJ In tank Fuel pump Bypass..Also known as SWAMPY BYPASS.. Reply with quote

Ok here it is.. The Swampy Bypass Write up...

1st thing you do is make sure that your fuel pump is the problem..
That means eliminate all other possibilities . Change the fuel fiter First ..
Then go to the fuel rail.. On the drivers side of the engine there is a Shraeder valve.. Get a fuel pressure tester from auto zone.. (Rent it if you want..)
You should have 39# of fuel pressure with the key on... If you do not .
Locate the vacum hose to the Fuel pressure regulator..
(Round thing on the drivers side of the enging at the rear of the fuel rail ON 93-95 models..) With the engine running pull the line.. The engine should keep running .. The reinstall the line.. IF the engine stumbles . Your Regulator could be bad...
ON 96 and Up Models your Regulator is on the canister.. Check is the same.. Just harder to do since you have to drop the tank..
Then If your regulator checks out ok or you couldnt get your engine runnig to check it...
Do one more simple test just to make sure....
Take a cup of gasoline... Pour a small amount down the throttle body.
Get someone to start the engine... If it starts pour a little bit more if it should keep running then wait.. If it stalls without gas...
It is probably your fuel pump..

I started by ordering the fuel pump..

Here is a picture of it installed on my rig...
I got it from Jegs.. It is part # is 121-2225 Here is a link.http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=120563&prmenbr=361

Then I cut a hole in the floor.. You can drop your tank if you want but I had 22 gallons of fuel in the tank when my pump went bad...So I cut mine..

Be very carefull your fuel lines are under there..
Then I removed the stock canister .. Visible in the picture..

This will take a large screw driver.(Put it on the ridge and tap the cap loose..) Go under the Jeep and find the plug for the fuel pump and unplug it..Pull off the fuel lines.. ANd remove the canister..
(If you are going to cut the hole ...measure 18" from the tailgate trim and 18 inches from the drivers side wall and drill a large hole be very carefull you should be able to see the canister and trim it out accordingly..)
With the canister out.. Set it on a work surface..
Be carefull of the fuel level sender.. It can be popped off with a screw driver..
It will take a while but carefully open the top of the canister.. IT is obvious how to do it but be carefull not to break the clips.. (This may require two people but I did it on my own.)


When the canister is cracked open.. You will see the pump.
Open the bottom as well to access the in canister fuel filter.. Clean that well..


Cut the thin fuel line that holds the pump in. and pull it out.(Disconnect the wires and take them with you..
IT should look like this..


Test the pump on your battery one more time just to be sure..

Now that you are positive the pump is crap.. Throw it as far as you can...

Take your new pump and attatch some short wires to it...
Test it on the battery.. (Not for long it hurts the pump to run dry..)
Once you are sure the new pump is good proceed..

Install a piece of fuel line from the top of the canister and let it go to the bottom of the canister and connect it to the in canister filter...


Reinstall the canister , lines and feed the plug down.. Then you are ready for the next step..
Crawl under the Jeep.. You will see a fuel filter canister Drivers side (93-95)
Follow the fuel line to the unit body rail right in front of your control arm.
Cut the fuel line.. You want to remove about 7 or so inches..
Put the fuel line on both sides of the pump and slide it over the stock hard line.. Use 4 hose clamps to tighten it up..
Do not crush the stock fuel line.. Mount the pump to the inner unit body rail.. LIke above picture.. While you are at it make a small jumper with a loop on both sides and ground the pump to one of the mounting screws..

Take another piece of wire and run it along the fuel line to the plug that you unplugged earlier. The #1 location on the wire is the fuel pump feed..
(I am not going to tell you a color because it may be different.)
Take a test probe and find the one thats hot when the key is on.. ON mine its red with a tracer..

Cut the wire in half..
On the engine side of the wire crimp the lead and run that wire to your pump positive side...



Here is a picture of the ground side notice it runs to mounting screw like I said....

(this is a picture I took today.. 12/22/04 it shows dirt and sticks and all kind of crap that the pump has been thru..)

Here is a picture of how I ran my wire back up the fuel line..


make sure all connections are tight and use dielectric grease on electrical connections.. (Remember dont over tighten the fuel lines.)
Fire it up you should be done....

Note the pump makes a noticably whine.. (Typical to any high performance fuel pump.. ) It can be quieted down By isolating it from the frame with some type of rubber grommets or something.. You are on your own there..Mr. Green
If you have any questions drop me an Email..
If you have a 96 or newer ZJ/WJ Drop me an email ... Its a little different for you... You will need an inline fuel pressure regulator and it gets alot more complicated...

Thank you for takeing the time out to read this long ass post..
Look around here for more writeups of stuff I have done.. Like Half doors and back hacking...

rofl
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Unless you include the sawzall work..

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Code3TJ
Hacker
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Joined: 01 Jan 2004
Location: Uzbekistan

PostPosted: Wed Dec 22, 2004 11:29 pm    Post subject: Reply with quote

And here's the write-up on the tech page. Wink
http://jeephorizons.com/tech/zj_fuel_pump.html
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SpeedMaster
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Joined: 06 Feb 2006

PostPosted: Mon Feb 06, 2006 2:11 am    Post subject: Reply with quote

Have done the 'cut-through' to access my fuel-pump.
I'm not going to do the by-pass trick since I've got a -98 with the fuel-pressure regulator sitting on top of the fuel-pump assy....
And now that I've got the 'access-hitch' in my trunk I don't see why I shouldn't stay stock...

Hmm...I just wanted to notice other people following this write-up that the distance between the floor-sheetsteel and the plastic tank is very small...
I was very cautious when I cut my hole up and managed not to damage the tank at all...but it's very easily done...hence my warning here...

BTW...with the tank filled up...you will definitely get fuel leaking out on the floor...don't ask why I know this...
Soo...I strongly recommend that you siphon out a few gallons of fuel before trying to remove the fuel-pump assy from the tank...

//Ted
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Jeep GC -98 5.2Ltr V8 Limited
LandRover STW -76
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swamp boy
Cherokee Muderator
Cherokee Muderator


Joined: 01 Jan 2004
Location: New Orleans LA.

PostPosted: Tue Feb 14, 2006 5:51 pm    Post subject: Reply with quote

Hahahaha... I think I wrote in my writeup that there wasnt much gap between the floor and the tank... But good idea to post it here.. It indeed is a very small gap and the fuel lines are in that area as well ....

I am currently looking for a Fuel rail off of a 97 or newer.. That I can swap on to mine so I can put an Inline regulator on my Jeep..
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jwilliman
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Joined: 13 Mar 2006

PostPosted: Mon Mar 13, 2006 4:14 pm    Post subject: Reply with quote

I am interested in doing this on my 98. When I start up cold, it takes about 6 or 7 seconds to start but if i shut the engine off and try again within 30 min. it starts up fine. What is involved in doing this to a 98 with the inline fuel pressure regulator and what parts do I need?
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rogbrown
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Joined: 12 Apr 2006
Location: Phoenix

PostPosted: Wed Apr 12, 2006 5:34 am    Post subject: MSD Pump Pressure Reply with quote

Swamp Boy,

The MSD pump (PN 2225) puts out 120 psi all the time and your system is set to run off of 40 psi. I don't see where you put a regulator in-line to cut the pressure down.

So how does your engine run using120 psi all the time?

Do you get better mileage using the higher fuel pressure over the factory pressure?

Thanks.
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li'l jeep
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Joined: 12 Feb 2007

PostPosted: Mon Feb 12, 2007 10:28 pm    Post subject: Reply with quote

what are the extra steps needed for a swampy bypass on a 97 grand cherokee (5.2L)? i will be dropping the tank also.
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ZJDAB
Member


Joined: 28 Aug 2008
Location: MD

PostPosted: Sat Aug 30, 2008 4:00 pm    Post subject: Picutre of locationiones of el fuel pumpo Reply with quote

Just thought this may help....as i did miss my point of reference

http://images.kurklin.multiply.com/image/2/photos/25/500x500/4/DSCN6816.JPG?et=WC9hmbzg9CIkJS5Jyn%2BAaQ&nmid=99148069


The hole has a 8 1/2 inch diameter

starts 13 inchs from the lock and its center is 3 1/2 inches from lock
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don4life
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Joined: 06 Feb 2011
Location: holland, mi

PostPosted: Sun Feb 06, 2011 4:58 pm    Post subject: Reply with quote

i know this is kinda old post but i just put this pump on my 95 5.2 zj and now it is fouling the plugs in about 5 mins of running because it seems to be running very rich........so i was wondering what you did to regulate the fuel pressure??
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