3rd Gen Tech: Walbro pump and Tank Vent
 

Walbro GFS-392 Install with pics and allot of information!

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.

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.

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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.

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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. (Not shown.)
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”

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Here is a pic with 1 pump installed, (most of you will probably need or want one pump) and also a pic with 2 pumps installed. 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 75GPM at 0 psi. 2 Pumps should supply about 150 GPM 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.

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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 to cut the hose.

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After cutting, it’s important to clean the hose out. I used a Q-tip for this.

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Continued
 

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.

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Close up of pump install. 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 + GPM fro 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 GPM 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.

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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.

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For access to the stock fuel pump wire, you need to open the fuse box.

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Then, you need to unclip the box from its holder. There are 2 of these clips on the upper sides of the fuse block.

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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.)

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I landed the power wire to the fuse holder here.

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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.
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.

After dropping the tank, the first thing I did was the Tank Vent modification. Here’s the plugged stock fitting on the tank.

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Continued
 

Here’s what will be taking its place a little higher on the tank.

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Close up of the bulkhead fitting I used.

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Please note at this time any hole you drill in your tank or in the top of your fuel canister should be small enough that the fitting you put into it actually barely threads into it. This will help control the amount of sealing your O-ring (or Teflon washers) has to do.

Drilling the hole. This is where I chose to put the vent fitting. When drilling the hole, hold a cup or something on the inside of the tank, under where you are drilling to catch any shavings that drop into the tank.

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The hole, and then a pic of the fitting installed.

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To remove the pump, first mark everything so it will go back the same.

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Using a punch and hammer, lightly tap the retaining ring CCW to remove it.

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This is the stock canister, where the remainder of the modifications will take place. If you wish to leave the option open to revert back to stock, purchase the Liberty canister and modify that one, instead. (P/N is in the parts list.)

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Disassemble the pump canister. I removed the pump and the brackets that hold it (They are permanently glued), the sending unit, and I separated the top from the fuel pump cup.

I cut the pump wires off the inside connector. You may wish to leave them, but if you do, make sure you secure them so they don’t interfere with anything.

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Here are the 2 siphon hoses we need to mount to the fuel canister lid.

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Continued
 

Begin by grinding the stock inlet fitting and ribs off the top and underside of the lid, drill a hole just large enough to thread the fitting in and install the first fitting.

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Underside

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Repeat for the 2nd fitting

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Underside

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When installing the siphon tubes, it’s important to get the length right. It makes it easier if you bend the tube before installing them by forming them with your hands. Remember, the lid will collapse about ¾” so allow for that also.
Here’s pics of my tubes in their final collapsed position.

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These next pics show the bottom of the fuel cup before and after adding additional holes to it. The additional holes allow the cup to fill faster. The holes are drilled in the bottom of the cup, but toward the left sidewall of the cup, so they do not speed up the draining of the cup as much when fuel is sloshing forward or backward. There is a plastic “Screen” that pops out easily with a screwdriver. Make sure you remove it before drilling! I recommend drilling from the bottom side into the cup.

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I retained the stock high PSI return line. Disregard the blue wire routing in this pic, I was experimenting with how to run it without using a zip tie.

Pic of tank reassembled, ready to go back in.

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Continued
 

Before installing the tank, I removed the old feed line completely off my truck, and put my AN fitting on my filter housing and connected the new line to it.

Here are a few post install pics, enjoy!

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There are several reasons I chose the GFS-392 pump to work with. I’m only going to list 10.

1). Familiarity. Go with what you know. Before this Diesel thing took off with me, I was in to Performance Gas motors. I still am, actually. The gas motor world is where I was first exposed to the GFS-392.

2). Personal Experience. I have a GFS-392 on my Holley Commander 950 fuel injected Off Road Buggy, and have personally had 4 years of trouble free off road service from it.

3). Availability. ALL the pumps out there are probably reliable. (Except the one in the stock Dodge fuel tank, LOL!) In the unlikely event something DOES go wrong, I already have a spare GFS-392 pump on hand. For those of you that don’t have a spare, one can be had for a little over $100 just about ANYWHERE it might fail. These things are popular, and plentiful! Something most people don’t think about until their $300-$400 High Zoot pump OR their Stock pump goes out in Nowhere, USA and they can’t get one for a couple days.

4) Price. Without a doubt, they are less expensive to purchase OR replace than either the stock pump that comes in the Dodge, or just about any of the competitive pumps. For reference, $212.00 list for the paper weight Dodge put in the tank, but I’ve seen it as cheap as $165.00, and about $300.00+ for “other” aftermarket pumps (No install kit).

5) Adaptability. It’s small, and it fits practically anywhere. It was used originally to pump gasoline, so I’m not too concerned about ULSD ruining it by lack of lubrication! (I run a lubricant in my fuel, anyway.)

6). Replacement. It doesn’t get any easier to replace, 10-minute job tops, depending on where YOU decide to put the thing, not where it fit, or in Dodge’s case in the Fuel tank!

7). Performance. Flow rates and pressures that will support upwards to 800HP. If you want more, Start off with one GFS-392, and then when you finally get to the point where you need more, add another one for a whole lot less than replacing your system with any other system out there.

8). Ease of installation. I’ve read some people consider the GFS-392 a difficult system to install. Nothing could be further from the truth! It’s dirt simple. It’s definitely no tougher than installing any other aftermarket pump. Once you inform yourself about it, you wont believe how easy it is to understand, and install.

9). Time effective. There are companies out there that offer complete kits for those who want or need something Turnkey, and quick.

10). Quiet operation. Although I “Hear” some of the other pumps are working on their noise levels.

In closing out this portion of my post, I have NOTHING to gain by providing you with my opinions, reasons, and methods of installation. I’m not selling ANYTHING.

The Diesel aftermarket is a VERY COMPETITIVE place. Who you are talking to and trusting as an “Authority” on the subject might just have something to gain by convincing you that you need something more expensive.

Here is a copy of a spec sheet and graph for the GFS-392

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Most of my fittings and hose came from Summit

Parts list for my install:

Part Number Part Description QTY EA PRICE

14-FPA 7/16” Pickup assembly 2 24.00 48.00
*5140832AB Jeep liberty fuel canister 1 71.76 71.76
G3727 Fram Fuel Filter 1 15.00 15.00
GDP-Bypass/1540CK Bypass Pressure Reg. and adj. Kit 1 90.00 90.00
GSL-392 Fuel Pump 1 125.00 125.00

Fittings
1- -8AN to filter in and out
Part Number Part Description QTY EA PRICE

EAR-9892086ERL FEMALE 8 MALE 6 REDUCER 1 9.00 9.00
EAR-9919EFGERL -8 AN TO 12MM-1.5 ADAPTER 1 12.00 12.00
SUM-220648 -6AN TO 3/8 NPT ADAPTER 1 3.00 3.00
SUM-220687 -6 90 HOSE END SWIVEL 1 13.00 13.00
SUM-220690 -6AN HOSE END STRAIGHT 3 4.88 14.64
SUM-220836 -8 AN MALE TEE 1 10.00 10.00
SUM-220846 -8AN TO 3/8 NPT ADAPTER 1 3.00 3.00
SUM-220890 -8AN HOSE END STRAIGHT 2 6.95 13.90
SUM-220887 -8 90 HOSE END SWIVEL 2 6.95 13.90
**128-3040 -8 AN TO 10MM-1.0 ADAPTER 2 7.00 14.00

Fuel Line
SUM-230815 S.S. BRAIDED HOSE-8 15 FT 1 63.00 63.00
SUM-230606 S.S. BRAIDED HOSE-6 6 FT 1 20.95 20.95

* Purchase from Dodgeparts.com This is optional; you could modify your existing fuel canister. Included here in case you want to leave the “Return to stock” option open.

**Purchase at: Walbro External Fuel Pumps they also sell them in –6 if you are only doing one pump.


TOTAL COST for one pump install like I did it, $500.00

great job, this will come in handy when i re do my fuel system thanks. :U:

Thanks! Let me know if you have any questions, and Good luck with your modifications! :U:

Dang good write up!

I've been looking at a 392 for teh pulling truck... Gonna make the jump now!

why did you go with duels? i have a single and the absolute bare minimum psi i have seen is 17 psi. it idles at 19. 17 was up a bridge with a traler in its ass. how much power you putting down?

nice write up :U: