here it is, the Swampy Bypass
word of warning, this write-up is my experience and is for
discussion purposes only. If you choose to make similar modifications
your vehicle, they are at your own risk. Please take all appropriate
precautions, especially with gasoline and any sources of ignition.***
The first thing you want to do
is make sure that your fuel pump is the problem. That means eliminate
all other possibilities. Change the fuel filter first. Then go to the
fuel rail.. On the driver's side of the engine there is a Shraeder
valve. Get a fuel pressure tester from Auto Zone or a similar parts
store. (They'll rent it to you if you want.) You should have 39 pounds
of fuel pressure with the ignition in the "on" position.
If you do not, locate the vacuum hose to the fuel
pressure regulator. It's the round thing on the drivers side of the
engine at the rear of the fuel rail on 93-95 models. With the engine
running, pull the line. The engine should continue running. Then
reinstall the line. If the engine stumbles, your regulator could be
bad. On 1996-present models, the regulator is on the canister. Check it
using the same method. It's just harder to do since you have to drop
the gas tank.
If your regulator checks out
okay or you couldn't get your engine running 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 keeps running then wait. If
it stalls without gas. it is probably your fuel pump.
I started by ordering the fuel
Here is a picture of it
installed on my rig. I got it from Jegs. It is part # 121-2225
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 extremely careful -
your fuel lines are under there.
Then I removed the stock
canister which is visible in the picture.
To remove it, you'll need 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 careful. You should
be able to see the canister and trim it out accordingly.)
With the canister out, set it
on a work surface. Be careful 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 careful
not to break the clips. (This may require two people but I did it on my
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
It should look like this.
Test the pump on your battery
one more time just to be sure it's bad. Now that you are positive the
pump is crap, throw it as far as you can...
Take your new pump and attach
some short wires to it. Test it on the battery, but not for long -
running the pump dry for any length of time will damage it. Once you
are sure the new pump is good proceed.
Insert a piece of fuel line
into the top of the canister and thread it to the bottom of the
canister. Connect the fuel line to the in-canister filter.
Reinstall the canister, fuel 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 on the driver's side (93-95). Follow the
fuel line to the unit body rail directly in front of your control arm.
Cut the fuel line. You want to
remove about 7 inches or so. Put the fuel line on both sides of the
pump and slide it over the stock hard line. Use four hose clamps to
tighten it up, but do not crush the stock fuel line. Mount the pump to
the inner unit body rail. 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 that's hot when the key is on. On mine it's 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 how I ran
my wire back up the fuel line.
Make sure all connections are
tight and use dielectric grease on electrical connections. (Remember,
don't over tighten the fuel lines.) Check for any fuel leaks before you
fire it up you should be done....
Note the pump makes a
noticeably 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 with that one.
If you have any questions drop
me an email. If you have a 96 or newer ZJ/WJ, send me an email as it's
a little different for you. You will need an inline fuel pressure
regulator and it gets a lot more complicated.
Thank you for taking the time
out to read this long ass post. Look around here for more write-ups of
stuff I have done - like half doors and back hacking...