XR4Ti Archived Tech Articles

    Walbro 255 liter per hour Fuel Pump Installation - Chris Grayson's comprehensive write-up on the installation of the Walbro 255 liter/hr fuel pump in place of the XR4Ti's stock in-tank fuel pump.


Post Date:    Thu, 11 Apr 2002
Subject:      Walbro GSS340 Fuel Pump Upgrade Installation (XR4Ti)
List:         imon@lists.merkurowners.org



There are two reasons for installing an upgraded fuel pump in an XR4Ti. 
The first reason is obvious - you need more fuel for your modified 
engine. The second reason is unfortunate - one of your fuel pumps died. 
Whatever your reason, the Walbro GSS340 255 liter per hour high 
pressure pump is a great choice. It's dependable, quiet (you cannot 
hear it running in an XR4Ti), and cheap! I purchased mine from J.D.'s 
Performance online at www.jdsperformance.com [Editor: link dated April
2002) for $109. Anyway, I figured that I would create a write-up on the 
project in case anyone would like to perform this upgrade themselves. 
Basically, this procedure involves removing the two existing fuel pumps
and replacing it with the GSS340, and then extending the high pressure 
fuel pump wiring to the fuel tank to control the new fuel pump. The old 
low pressure fuel pump wiring will no longer be used.


Recommended Items:

Walbro GSS340 Pump (255lph High Pressure)
1' fuel hose
25mm to 50mm hose clamp
14-16GA butt connectors (blue)
14-16GA ring connector (blue)
12ft 12GA red stranded wire
6ft 12GA black stranded wire
Electrical tape
Epoxy


Recommended Tools:

Wire crimpers
Wire stripper
17mm socket
13mm socket
10mm socket
8mm socket
Screwdrivers
Jack
Two jack stands
Hammer
Chisel
Rags


Recommended Steps:

1.) If possible, remove as much fuel from the tank as you can. This can
be done using a few methods:

    a) Use a siphon pump through the filler tube to suck out the fuel 
into a gas can.

    b) Disconnect the fuel hose from the return side of the fuel pressure
regulator, and attach a separate fuel hose to carry the fuel to a gas 
can. Turn on the engine. Since so little fuel is used at idle, most of 
the fuel will flow out the return hose into the gas can. This, of course, 
only works if you don't have a dead fuel pump.

    If you cannot remove most of the fuel from the tank, the tank will be
VERY heavy when you go to lower it from the vehicle. In addition, 
several gallons of fuel could spill out when the tank is pulled away from 
the filler tube. Make every effort you can do empty the tank as best you 
can.

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2.) Lift the left rear seat bottom forward and remove the bolt that 
attaches the rear seat belt receptacles to the floorpan.

3.) Remove the left rear seat back by removing the four screws (two on 
each side) that attaches the rear seat back hinges to the rear seat back. 
Lift the rear seat back away.

4.) Remove the left rear side bolster by carefully bending the retaining 
tabs at the bottom and lifting the side bolster up and away.

5.) Remove the 2 screws retaining the left shock bolt cover and lift 
away the shock bolt cover.

6.) Pull up the plastic cover on the left rear seat belt mechanism and 
remove the retaining bolt.

7.) Disconnect the two spade terminals that connect to the rear speaker.

8.) Remove the screws retaining the left rear plastic side shelf 
*including* the 2 screws at the rear of the left back seat wall panel. 
Lift away the left rear plastic side shelf.

9.) Remove the seven screws that attach the rear hatch wall panel to 
the body. Disconnect the hatch light wiring and lift away the rear 
hatch wall panel.

10.) Remove the hatch floor cover.

11.) Remove the three plastic push retainers that secure the left rear 
hatch wall panel to the body and lift away the left rear hatch wall 
panel.

12.) Remove the stowed jack and tire iron.

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13.) Make sure that the vehicle has cooled completely. Fuel and hot 
exhaust pipes don't mix.

14.) Open the fuel door and remove the three screws retaining the filler 
tube to the body. Place the gas cap and screws aside.

15.) Raise the rear end of the vehicle and support it with jack stands.

16.) Remove the exhaust pipes *if necessary*. The fuel tank can be 
removed without removing stock exhaust pipes, but this may not be the 
case with an aftermarket exhaust.

17.) Near the entry point of the filler tube into the fuel tank, remove 
the bolt retaining the filler tube bracket to the lip of the fuel tank.

18.) Place a bucket, box, or other object beneath the fuel tank, 
leaving a 4 to 6 inch gap between the two. This will be used to support 
the tank as you begin to lower it.

19.) Remove the six screws retaining the fuel tank shield to the body.

20.) Carefully remove the two bolts retaining the fuel tank straps to 
the body. Support the tank such that it does not suddenly drop on the 
supporting object you placed beneath.

21.) With the fuel tank resting on the supporting object, use a small 
screwdriver to remove the two fuel clips at the fuel line connections 
at the top of the tank. Once the clips are removed, disconnect the fuel 
lines. Also disconnect the vent tube, the fuel pump wiring connector, 
and the fuel gauge wiring connector.

22.) Pull the fuel tank away from the vehicle.

23.) If the filler tube grommet remained on the filler tube, remove it 
and re-install it on the tank.

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24.) The in-tank fuel pump is secured by a large locking ring. The ring 
has several tabs sticking up. Using a hammer and chisel, carefully tap 
the locking ring counterclockwise until it releases. Alternate the tabs 
you are tapping on occasionally to help ease the release and to prevent 
damaging a tab.

25.) Lift away the locking ring, and remove the fuel pump assembly from 
the tank. A small screwdriver may be used to separate the pump 
coverplate from the tank in case the o-ring is sticking.

26.) Clean any rust and small pebbles that fall on the fuel pump 
coverplate's seat on the tank. Be careful not to let anything drop into 
the tank at all times!

27.) Remove the two spade connectors that connect to the top of the in-
tank fuel pump.

28.) Remove the two small screws that retain the fuel pump to it's 
bracket.

29.) Separate the fuel pump and the rubber fuel hose from the assembly. 

30.) Remove the dangling fuel pump wiring by snipping it away at the 
"through-wall" connector on the coverplate. Do not snip away the fuel 
gauge wiring!

31.) Drill a hole through the coverplate large enough to pass the new 
fuel pump wiring through it. Deburr the hole as necessary.

32.) The new pump will now be placed where the old in-tank pump used to 
sit. Cut a section of fuel hose long enough such that the distance from 
the tip of the new pump outlet to the steel fuel tube is about 1/4". 
Slip the fuel hose over the pump outlet and slip that over the steel 
fuel tube.

33.) Attach the sock filter to the bottom of the new fuel pump such 
that the sock extends toward the rear of the vehicle. You may have to 
remove the pump from the fuel tube, affix the sock filter, and then 
stick the pump back on the steel fuel tube a few times to get it 
positioned properly.

34.) Tighten the hose clamps to the fuel hose at the fuel tube and the 
fuel pump outlet.

35.) Use a steel hose clamp to attach the fuel pump body to the bracket. 
If the 1/4" gap from the previous step was attained, there should be 
just enough pump body for the hose clamp to wrap around.

36.) Wrap a thickness of electrical tape (or otherwise cover the wiring) 
at the point where the wiring will pass through the coverplate. Try not 
to tape the wire inside of the tank - the gasoline may eat it.

37.) Install a grommet in the drilled hole that the wires will pass 
through, if possible.

38.) Plug the supplied fuel pump wiring pigtail into the fuel pump, and 
guide the wiring though the drilled hole.

39.) If a grommet was not installed in step 26, apply a large glob of 
epoxy to the fuel pump wires and the drilled hole. What we are trying to 
accomplish here is to prevent the wiring from moving around the drilled 
hole, which could rub the wires bare and perhaps cause a spark. Allow 
epoxy to dry.

40.) Carefully lower the fuel pump assembly into the fuel tank. Make 
sure you remember to install the o-ring.

41.) Place the locking ring over the fuel pump coverplate and use the 
hammer and chisel to tap it clockwise into position.

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42.) Using a small flat blade screwdriver, carefully remove the hairpin 
clip from the fuel line on the input side of the external fuel pump, and 
disconnect the fuel line. Have rags available, for gasoline will spill 
out of the fuel line.

43.) Carefully remove the hairpin clip from the fuel line on the output 
side of the external fuel pump and disconnect the fuel line.

44.) Carefully remove the hairpin clip from the fuel line on the input 
side of the fuel filter and remove the "S-shaped" fuel line from the 
vehicle.

45.) Remove the three bolts attaching the external fuel pump to the 
welded body bracket.

46.) Disconnect the external fuel pump wiring connector and remove the 
pump from the vehicle.

**** Now would be a great time to change your fuel filter!

47.) Connect the fuel line that used to connect to the input side of the 
external fuel pump to the input side of the fuel filter. Install one of 
the three hairpin clips that were removed to lock the fuel line into 
place.

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48.) Work the grommet up from the floorpan where the external fuel pump 
wiring passes through.

49.) Cut the external fuel pump wiring between the branch point in the 
wiring harness and the floorpan grommet.

50.) Pull the floorpan grommet off of the wiring.

51.) Thread one of the bolts that once secured the external fuel pump to 
the welded body bracket into the hole in the floorpan grommet (this will 
seal the hole that remains from the removed wiring).

52.) Insert the floorpan grommet into the hole in the floorpan.

53.) Cut the external fuel pump ground wire a few inches from the branch 
point in the wiring harness. Place a piece of electrical tape over the 
end of the wire - it will not be used anymore.

54.) Use a butt connector to connect the external fuel pump power wire to 
the 12' length of 12GA red stranded wire.

55.) Carefully run the red wire into into the hatch area. Follow the path 
of the existing hatch wiring harness as it enters the left side of the car,
 passes below the rear washer fluid bottle, runs along the rear end of the 
hatch behind the jack stow bracket, and to the in-tank fuel pump grommet.

56.) Secure the red wire to the existing hatch wiring harness in many 
places using electrical tape.

57.) Attach a ring terminal to the end of the 12GA black stranded wire.

58.) Remove the screw securing the ring terminal ground to the body below 
the hatch striker.

59.) Insert the black wire's ring terminal over the existing ring terminal 
ground below the hatch striker and re-install the screw.

60.) Carefully run the black wire behind the jack stow bracket and to the 
in-tank fuel pump grommet.

61.) Work the grommet up from the floorpan where the in-tank fuel pump 
wiring passes through.

62.) Cut the wiring for the in-tank fuel pump between the grommet and the 
in-tank fuel pump connector. Do not cut the fuel gauge wiring.

63.) Pull the wiring for the in-tank fuel pump out of the grommet.

64.) Your goal now is to connect the red wire from the fuel pump to the 
12GA red wire you ran though the body, and also connect the black wire 
from the fuel pump to the 12GA black wire you grounded below the hatch 
striker. Both wires should pass through the floorpan grommet just like the 
old wiring used to. It is optimal to install a connector somewhere between 
the fuel pump and the floorpan grommet, but not necessary. I ended up using 
the old connector for the external fuel pump as the connector for my new 
fuel pump. This option looks very professional, and is extremely functional.

65.) Tape the red wire and the black wire together from the fuel pump to the 
connector (if installed), and from the connector (if installed) through the 
grommet and to the wiring harness branch near the right rear taillamp. Use 
electrical tape. Note that the grommet can be slid along the wiring to 
facilitate the continuous application of tape.

66.) Use electrical tape to tape the fuel gauge wiring from the fuel pump 
to the wiring harness branch near the right rear taillamp.

67.) Insert the floorpan grommet into the hole in the floorpan.

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68.) Lift the fuel tank up, allowing the fuel filler tube to enter the tank.

69.) Support the fuel tank with the bucket, box, or other supporting object 
you used during disassembly.

70.) Connect the pressurized fuel line to the fuel tank and insert the 
hairpin clip.

71.) Insert the duckbill clip on the return fuel line and connect it ot the 
fuel tank.

72.) Connect the fuel gauge wiring connector and the fuel tank vent tube.

73.) If necessary, connect the fuel pump wiring connector.

74.) Make sure the fuel tank straps properly pass through the fuel tank 
shield, raise the shield, fuel tank, and straps, and insert the bolts that 
retain the fuel tank straps to the body.

75.) Install the six screws that retain the fuel tank shield to the body.

76.) Install the bolt that attaches the fuel filler tube bracket to the fuel 
tank lip.

77.) Install the three screws that retain the fuel filler tube to the body 
through the fuel filler door.

78.) Lower the vehicle to the ground.

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79.) Install the stowed jack and tire iron.

80.) Install the left rear hatch wall panel, securing it with the three 
plastic push retainers.

81.) Install the hatch floor cover.

82.) Connect the hatch light wiring to the rear hatch wall panel and 
install the rear hatch wall panel, securing it with the seven screws.

83.) Install the left rear plastic side shelf, securing it with the 
screws. You'll have to slide the front edge of the shelf behind the left 
back seat wall panel.

84.) Connect the two spade terminals that connect to the rear speaker.

85.) Install the left rear seat belt mechanism, securing it with the 
retaining bolt. Make sure to install the round black spacer between the 
mechanism and the body, inserting the dowel into the hole in the body. 
Snap the plastic cover on the seat belt mechanism in place.

86.) Install the left shock bolt cover, securing it with two screws.

87.) Install the left rear side bolster. You may have to carefully bend 
the retaining tabs at the bottom to faciliate installation.

88.) Install the left rear seat back by installing the four screws (two 
on each side) that attaches the rear seat back hinges to the rear seat back.

89.) Install the bolt that attaches the rear seat belt receptacles to 
the floorpan.

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90.) Partially fill the fuel tank. Four gallons of fuel should be fine. 
It is recommended that you don't insert too much fuel, just in case 
you have to drop the tank again for any reason.

91.) Prior to turning on the engine, you can pressurize the fuel system 
by turning on the ignition for a few seconds, thereby letting the fuel 
pump cycle, turning off the ignition, and repeating several times. Or, 
if you would like, you can simply crank the engine for ~15 seconds 
until the fuel pressure builds and the engine fires.

92.) Once the engine is running, check underneath the vehicle for fuel 
leaks.

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Published by Chris Anglin.