Fuel Tank Relocation & Fuel System

Fuel cell mounted by previous owner. Click to enlarge – use browser back button to return.

When I purchased this truck, the in-cab tank had already been removed and replaced with a sumped poly fuel cell,  professionally mounted in the bed with baler twine and bungy cords.

The truck had a mid-late  80’s 350 small block Chevy swapped in using the standard engine mounted mechanical pump which was gravity fed from the fuel cell.

 

New tank includes mounting hardware. Click to enlarge – use browser back button to return.

I considered relocating this fuel cell under the bed between the frame rails.  Knowing in the future I would swap the 350 for a 5.3L, I decided to buy a new “relocation tank” instead of going thru the hassle and expense of buying the fittings needed to re-use the poly fuel cell, then modifying it later to an in-tank electric pump for the upcoming fuel injection.

 

I purchased the standard top-fill relocation tank from LMC merely because they had the cheapest shipping at the time.  From what I can tell, the LMC tanks are likely the same manufacturer as the Brothers tanks.   With the tank I purchased the correct 30 ohm sending unit to work with my stock 1966  fuel gauge.  I chose the top fill tank over the side fill as I did not want to deal with the extra hassle of trying to locate the fuel filler for the side fill.  I chose a fairly cheap, but good quality fuel cap from eBay.

Mounting new tank between frame rails. Click to enlarge – use browser back button to return.
Great placement of fuel filler. Click to enlarge – use browser back button to return.

Installation was rather simple and straight forward.  I did have the luxury of installing before I put in the wooden bed.  This made for a much easier job installing tank, sender, hose, etc.  I ran the truck this way for only a couple weeks before I decided to move forward with the 5.3L swap.

Mounted with straps. Click to enlarge – use browser back button to return.

 

Tanks Inc. PA-2. Click to enlarge – use browser back button to return.

For the 5.3L fuel injection system I would need an electric fuel pump.  I considered modifying the current fuel sender to accept an in-tank pump, but the would require some braising or other welding to allow the pump to attach to the sender supply tube.  I did not have the knowledge or tools to do this.  My best bet was to  use a universal in tank unit made for this type of system and included the pump and baffle and every thing I needed to do it correctly.  While I could have purchased the unit without a pump and used the trusty ol’ Ebay Kemso pump, but for about $20 more the Tanks Inc. PA-2 unit came came complete with a quality Walbro 255LH pump.  I purchased the Tanks Inc. PA-2 from Summit Racing online.

 

No hole saw, but this nibbler makes short work of the cutting . Click to enlarge – use browser back button to return.

Installing the Tanks Inc. unit meant easily dropping the tank since I had already installed the wooden bed floor.

The universal sending unit was a straight-forward install.  Assemble the pump, baffle, pickup and return tubes, cut the hole in the expensive tank, drill some holes, install gasket and screws… done.  I found plenty of online videos if there was any confusion.

 

 

Tanks Inc. PA-2 installed. Click to enlarge – use browser back button to return.

The fuel line and -AN fittings came in a kit from Ebay complete with all needed connections.  These are decent quality fittings and hose from which I have had no issues.

Fuel line and fittings ready to install. Click to enlarge – use browser back button to return.

 

Wix 33737 Filter/regulator. Click to enlarge – use browser back button to return.

Since I was using a return-less fuel rail, I needed to include the infamous “Corvette” fuel regulator/filter.  There are many manufactures available for these regulator/filters.  After some research, I chose a known quality Wix brand for this filter.  A Wix 33737 from O’Reilly was only a few dollars more than the questionable Ebay equivalents.

 

 

 

Wix 33737 Filter/regulator. Click to enlarge – use browser back button to return.

The regulator/filter was installed in a convenient location on the frame near the tank.  This made for a short return line and easily allowed the supply line to run to the rail along the inside of driver side frame.  A vent line was attached to the supplied tank vent tube and routed over and above the tank for proper venting  thru a fuel vent cap from the original GMC 5.3L donor vehicle.

 

Universal Fuel Level sending unit. Click to enlarge – use browser back button to return.

The original sending unit included a 30 ohm fuel level sender, so this needed to be adapted to 90 ohm or replaced.  It was much cheaper to replace with a standard universal unit.

This was easily done with a $20 unit from Ebay.    The universal fuel level sender required a 3″ hole in the tank. I found that with very slight modification, the unit would fit into the existing fuel sending unit opening and utilize the original o-ring and locking ring.

 

 

Plug welding mounting holes in top plate.. Click to enlarge – use browser back button to return.

I disassembled the new universal sending unit so I could easily make the necessary modifications.

This included notching the top plate and welding the mounting holes closed.  I also had to make the plate diameter very slightly smaller (less than one millimeter) by using the bench grinder.  By the time I got done with this, there was no galvanizing left on the plate, so I shot a layer of primer on it before reassembly just to slow down the inevitable rust.

 

 

Shaft and float arm adjusted per included install instructions. Click to enlarge – use browser back button to return.

Adjusting the length and float arm to the correct length was very easily done by following the included instruction sheet measurements for the specific depth of my tank.  10 1/2″ in this case.

 

 

 

 

 

Installing back into tank. Click to enlarge – use browser back button to return.

 

Using original o-ring and locking ring. Click to enlarge – use browser back button to return.

The original lock ring slipped right back in place successfully sealing the new sending unit in place.  Although the install instructions didn’t say it was necessary,  I added a ground wire as the original sending unit had.

 

 

 

 

 

I believe I covered all that was needed on this page, but here are the blog entries as I went along.

Blog entries about the tank relocation:
Bed floor upgrade and fuel tank install   December 4, 2019
Fuel system underway   March 14, 2020
Universal Fuel Sender     May 19, 2020