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Wow. Look at all the threads concerning Lift Pumps these days. It’s confusing to an experienced Diesel owner, much less the guy who just bought his first Diesel truck.
I put some of my reasons for choosing this particular pump and setup after the installation, at the end of the post, so those that are just into the install and photos can get what they want without wading through a bunch of typing first. It’s nothing too wordy, just some basic, logical conclusions I’ve drawn after researching the subject, and determining THIS is the system for me.
There are also some graphs, specs and additional info on the Walbro I’ve gleaned during my research. I put it there in hopes that it would help consolidate some useful information for those choosing a similar path, or just seeking information.
My installation will be custom, so I bought allot of parts and then put them together to MY liking. See the end of the post for a cost breakdown of what I did, and parts list. Keep in mind, if you are just adding one GFS-392, and don’t care for all the stainless braided hose, you can reduce the cost of installation and time spent quite considerably by using rubber fuel rated hose and push lock fittings. Also, most of this install can be done while keeping your truck running on the stock system. Once you drop the tank, that's when the changeover occurs.
Ok, Let’s jump into this thing with both feet!
Just your basic, run of the mill Walbro GFS-392 here.
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Here it is decked out in its standard installation kit. The foam cover and insulated clamps keep vibration transmission to the chassis to a minimum. I am actually not using the barbed fittings you see at either end. There will be some AN fittings on there, I just put them on so I could keep track of the copper gaskets that seal the input and output.
![]()
This is my proposed location for the pump installation. I’ll be using the bracket that comes off the upper portion of the frame that’s not being used for anything on my truck.
![]()
Here’s one pump attached to the custom mount I made that bolts into the fame bracket shown in the previous pic. Keep in mind; you don’t have to do anything this fancy or complicated to put one of these pumps on your truck. All that’s really required is a couple of holes and some sheet metal screws. The reason the pump is offset to the right on this bracket is to allow access to a filter and fittings that will be on the input side of the pump. (To the Left.) Also, note the ground wire just goes to one of the mounting bolts. I made the bracket out of some ¾” tube cut to length, and welded some short bolts to it.
The bracket bolt is 7/16” X 6”
![]()
Here is a pic with 1 pump installed, (most of you will probably need or want only one pump) and also a pic with 2 pumps installed.(From here on, two Walbro pumps should be referred to as an "Overkill Deuce" setup. LOL!) Since this is a bypass* system, and my fueling mods aren’t that far down the road, I decided on installing 2 pumps now. For reference, 1 pump should supply about 75GPH at 0 psi. 2 Pumps should supply about 150 GPH at 0 psi. (There is a flow graph at the end of this install.) That is the reason I went with –8 hose (1/2”) for the feed and supply lines..
*Note: In a bypass system, a bypass valve regulates the pressure. The fuel you don’t use gets returned back to the tank.
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Here’s a pic of the backside of the bracket with the 2 fuel pumps installed.
![]()
Begin running the new fuel lines by first measuring your hose for each leg of the run.
I accomplished this with the hose itself. My method was install a fitting, connect it to the component, and then lay it out along its proposed route. At the termination point, I make a mark on the hose, (allowing for a little slack) cut the hose and install the other fitting.
All of the tank connection hoses were run, cut, and made up before dropping the tank.
I used a metal cut off wheel in an angle grinder to cut the hose.
![]()
After cutting, it’s important to clean the hose out. I used a Q-tip for this.
![]()
![]()
The rest of the fitting and hose assembly is pretty self-explanatory. Here are some pics of the install. This first pic shows most of the plumbing, the tank is removed in this photo.
![]()
I want to point out at this time, the yellow jumper wire that runs from the upper pump to the lower pump. This is a key feature of obtaining 150 + GPH from 2 pumps Vs. 1. If I begin to experience fluctuating pressure and fuel delivery at low tank conditions because the pumps are sucking all the fuel out of the fuel basket, the plan is to replace this jumper with 2 wires that run to a switch in the cab. This will permit me to shut off the lower pump, reducing my GPH to 75 or less.
I decided to protect the pump with an input filter, a very common Fram G3727. It also is the filter I use to protect the GFS-392 on my Fuel injected Rock Buggy.
I fabricated an input and output manifold for the 2 pumps instead of plumbing them with Tee’s. After welding them up, I pressure tested the welds for leaks with air, and soapy water. This turned out to be quite the ordeal, and if I had it to do over, I’d just plumb in the tee’s.
![]()
![]()
Moving on to the electrical portion of the project, the first order of business was to get the + wire from the pump up to the fuse block area of the truck. I just ran the wire in the existing split loom wiring harness. It is located on the Driver’s side frame rail. I left the existing stock wiring in tact.
I chose to mount my relay right next to the fuse block. The cartridge on the left of the relay in the photo is for the fuse.
After soldering all the wiring connections to the relay connector, I filled the bottom of it with RTV to keep moisture out of it, and preserve the connections. The negative coil wire (Ground) is the brown one that is terminated to the chassis.
![]()
For access to the stock fuel pump wire, you need to open the fuse box.
![]()
Then, you need to unclip the box from its holder. There are 2 of these clips on the upper sides of the fuse block.
![]()
After releasing them, roll the fuse block out of the holder, revealing the wiring below it.
There are 4 color-coded connectors attached to the block. There are also like colored squares next to where these connectors plug in on the block. They are Black, Brown, Blue and Gray. (To remove, slide the red lock, then lift the bail completely, the connector will now separate from the fuse block.) In this pic, you can see the Blue and gray connectors and the gray color-coded marker. You can also see the location of the Orange wire with red trace that runs to the stock lift pump. (It’s the one with all the black electrical tape on it. I soldered in the positive coil wire to this wire. (For reference, the wire I used is Yellow.)
![]()
I landed the power wire to the fuse holder here. If you are doing this while leaving the stock system intact so the vehicle will still run, disconnect this connection until the final tank mods and changeover are complete.
![]()
![]()
Fuel pump operation is accomplished in the following manner: When the ignition key is turned on, the stock orange wire with red trace receives power. The power is transferred to the yellow coil wire, which is soldered to it. Current flows through the electromagnetic coil of the relay, energizing it, therefore transferring the Normally Open contact with the wire from the fuel pump, to the common terminal of the relay, with the battery positive voltage to it. Current now flows through the fuel pump motor, to ground.
The entire install to this point was done with the stock system still in place and running. Kind of handy, because I ALWAYS forget one fitting, Screw, washer SOMETHING! LOL!
Beginning with the dropping of the tank, my stock system is going away forever. If you wish to retain your stock system for whatever reason, omit the portions that delete it. I allowed myself a weekend to complete the project from this point, and had plenty of time.
After dropping the tank, the first thing I did was the Tank Vent modification. Here’s the plugged stock fitting on the tank.
![]()
Here’s what will be taking its place a little higher on the tank.
![]()
Close up of the bulkhead fitting I used.
![]()
I put some of my reasons for choosing this particular pump and setup after the installation, at the end of the post, so those that are just into the install and photos can get what they want without wading through a bunch of typing first. It’s nothing too wordy, just some basic, logical conclusions I’ve drawn after researching the subject, and determining THIS is the system for me.
There are also some graphs, specs and additional info on the Walbro I’ve gleaned during my research. I put it there in hopes that it would help consolidate some useful information for those choosing a similar path, or just seeking information.
My installation will be custom, so I bought allot of parts and then put them together to MY liking. See the end of the post for a cost breakdown of what I did, and parts list. Keep in mind, if you are just adding one GFS-392, and don’t care for all the stainless braided hose, you can reduce the cost of installation and time spent quite considerably by using rubber fuel rated hose and push lock fittings. Also, most of this install can be done while keeping your truck running on the stock system. Once you drop the tank, that's when the changeover occurs.
Ok, Let’s jump into this thing with both feet!
Just your basic, run of the mill Walbro GFS-392 here.
Here it is decked out in its standard installation kit. The foam cover and insulated clamps keep vibration transmission to the chassis to a minimum. I am actually not using the barbed fittings you see at either end. There will be some AN fittings on there, I just put them on so I could keep track of the copper gaskets that seal the input and output.
This is my proposed location for the pump installation. I’ll be using the bracket that comes off the upper portion of the frame that’s not being used for anything on my truck.
Here’s one pump attached to the custom mount I made that bolts into the fame bracket shown in the previous pic. Keep in mind; you don’t have to do anything this fancy or complicated to put one of these pumps on your truck. All that’s really required is a couple of holes and some sheet metal screws. The reason the pump is offset to the right on this bracket is to allow access to a filter and fittings that will be on the input side of the pump. (To the Left.) Also, note the ground wire just goes to one of the mounting bolts. I made the bracket out of some ¾” tube cut to length, and welded some short bolts to it.
The bracket bolt is 7/16” X 6”
Here is a pic with 1 pump installed, (most of you will probably need or want only one pump) and also a pic with 2 pumps installed.(From here on, two Walbro pumps should be referred to as an "Overkill Deuce" setup. LOL!) Since this is a bypass* system, and my fueling mods aren’t that far down the road, I decided on installing 2 pumps now. For reference, 1 pump should supply about 75GPH at 0 psi. 2 Pumps should supply about 150 GPH at 0 psi. (There is a flow graph at the end of this install.) That is the reason I went with –8 hose (1/2”) for the feed and supply lines..
*Note: In a bypass system, a bypass valve regulates the pressure. The fuel you don’t use gets returned back to the tank.
Here’s a pic of the backside of the bracket with the 2 fuel pumps installed.
Begin running the new fuel lines by first measuring your hose for each leg of the run.
I accomplished this with the hose itself. My method was install a fitting, connect it to the component, and then lay it out along its proposed route. At the termination point, I make a mark on the hose, (allowing for a little slack) cut the hose and install the other fitting.
All of the tank connection hoses were run, cut, and made up before dropping the tank.
I used a metal cut off wheel in an angle grinder to cut the hose.
After cutting, it’s important to clean the hose out. I used a Q-tip for this.
The rest of the fitting and hose assembly is pretty self-explanatory. Here are some pics of the install. This first pic shows most of the plumbing, the tank is removed in this photo.
I want to point out at this time, the yellow jumper wire that runs from the upper pump to the lower pump. This is a key feature of obtaining 150 + GPH from 2 pumps Vs. 1. If I begin to experience fluctuating pressure and fuel delivery at low tank conditions because the pumps are sucking all the fuel out of the fuel basket, the plan is to replace this jumper with 2 wires that run to a switch in the cab. This will permit me to shut off the lower pump, reducing my GPH to 75 or less.
I decided to protect the pump with an input filter, a very common Fram G3727. It also is the filter I use to protect the GFS-392 on my Fuel injected Rock Buggy.
I fabricated an input and output manifold for the 2 pumps instead of plumbing them with Tee’s. After welding them up, I pressure tested the welds for leaks with air, and soapy water. This turned out to be quite the ordeal, and if I had it to do over, I’d just plumb in the tee’s.
Moving on to the electrical portion of the project, the first order of business was to get the + wire from the pump up to the fuse block area of the truck. I just ran the wire in the existing split loom wiring harness. It is located on the Driver’s side frame rail. I left the existing stock wiring in tact.
I chose to mount my relay right next to the fuse block. The cartridge on the left of the relay in the photo is for the fuse.
After soldering all the wiring connections to the relay connector, I filled the bottom of it with RTV to keep moisture out of it, and preserve the connections. The negative coil wire (Ground) is the brown one that is terminated to the chassis.
For access to the stock fuel pump wire, you need to open the fuse box.
Then, you need to unclip the box from its holder. There are 2 of these clips on the upper sides of the fuse block.
After releasing them, roll the fuse block out of the holder, revealing the wiring below it.
There are 4 color-coded connectors attached to the block. There are also like colored squares next to where these connectors plug in on the block. They are Black, Brown, Blue and Gray. (To remove, slide the red lock, then lift the bail completely, the connector will now separate from the fuse block.) In this pic, you can see the Blue and gray connectors and the gray color-coded marker. You can also see the location of the Orange wire with red trace that runs to the stock lift pump. (It’s the one with all the black electrical tape on it. I soldered in the positive coil wire to this wire. (For reference, the wire I used is Yellow.)
I landed the power wire to the fuse holder here. If you are doing this while leaving the stock system intact so the vehicle will still run, disconnect this connection until the final tank mods and changeover are complete.
Fuel pump operation is accomplished in the following manner: When the ignition key is turned on, the stock orange wire with red trace receives power. The power is transferred to the yellow coil wire, which is soldered to it. Current flows through the electromagnetic coil of the relay, energizing it, therefore transferring the Normally Open contact with the wire from the fuel pump, to the common terminal of the relay, with the battery positive voltage to it. Current now flows through the fuel pump motor, to ground.
The entire install to this point was done with the stock system still in place and running. Kind of handy, because I ALWAYS forget one fitting, Screw, washer SOMETHING! LOL!
Beginning with the dropping of the tank, my stock system is going away forever. If you wish to retain your stock system for whatever reason, omit the portions that delete it. I allowed myself a weekend to complete the project from this point, and had plenty of time.
After dropping the tank, the first thing I did was the Tank Vent modification. Here’s the plugged stock fitting on the tank.
Here’s what will be taking its place a little higher on the tank.
Close up of the bulkhead fitting I used.
