FJ40 In-Tank Electric Fuel Pump Build (1 Viewer)

[reddingcruiser]

I have always figured that the factory guys know their stuff. While there are plenty of aftermarket external electric fuel pumps supplying fuel to a variety of engines, I believe the correct place for the pump is in the tank. There are a couple of good reasons why the factory put the pump in the tank:

• It keeps the pump cool by immersing it in the fuel.
• It provides the shortest distance from the tank to the pump.
• You don't have to listen to the pump buzzing.
• It accepts a OEM replacement pump. I have learned the hard way that not all external electric pumps are set up the same, making emergency replacements a challenge.
• The in-tank pump is half the size of it's external cousin.

So, here we go.

I looked at a number of pump setups online and decided the 90-93 GM/Chevy Pickup pump would be the easiest to modify, and the 5.7 TBI I have is the same vintage. I started my mission by buying a complete gas tank out of 93 Chevy Pickup, knowing I would need several key parts from the tank to get the pump to install the same as the OEM version.

This is the top of the GM tank,

Here are the parts I needed from the GM tank, including the stamped recess from the top of the tank.

Next job was to decide how to modify the OEM pump assembly. I could have purchased the pump assembly brand new for $230, but the complete tank and used assembly was only $35, and $45 for a new pump. Besides, I planned on chopping it up and couldn't justify cutting up a new one for an 'experiment'.

After some preliminary measurements from the FJ40 tank, this is what I came up with for an initial mock-up.

Next came the nerve racking part, cutting into a brand new FJ40 gas tank. The challenge was determining the exact location of the baffles and determining the final, permanent location for the fuel pump. I also had to take into account clearance issues with the passenger side seat. My seat are not stock and have plenty of room underneath, but there are some I had to make some provisions for the power seat mechanisms.

More tomorrow.

 

[Dynosoar]

Following

 

[diogenese]

It makes more sense to push modern petrol with high ethanol content to reduce the chance of vapour lock wich is always a possibility on a suction fuel system.

 

[Solace in Solitude]

Following!!

 

[budharris]

Following!!!

 

[78fj40mg]

Following!!!

 

[reddingcruiser]

Fortunately, the hole for the gas gauge sending unit is in a good spot for looking into the tank and determining the location of the pump. One thing I determined early on was I DID NOT want to end up on top of the drain plug because I figured that I would be able to use it to secure the baffle tray I needed to install later to ensure the pump did not run dry during steep climbs. This setup exists in most OEM tanks, particularly in off-road applications. I could probably have completed this project without the baffle tray since I never had fuel starvation issues when the pump was externally mounted, but I only wanted to go inside the tank one time.

I knew I would have to remove the fuel filler overflow tube and the center compartment vent tube. The good news is these are already built into the GM fuel pump assembly, as is the fuel return tube. I'll leave the stock FJ40 supply and return tubes and just cap them off, because you never know!!!

After measuring twice in hopes of cutting just once, I finally did the deed. You can see I pondered other locations while "measuring once".

When I started my plan was to install a substantial mounting ring to eliminate as much flex as I could in the top of the tank, have enough rigidity to form a seal and, yes, look cool. The depression for the fuel filler overflow tube needed to disappear in order to have a flat sealing surface for the mounting ring. The best way to do this was a little heat and a modified heavy duty C-clamp.

Once I had a flat surface, it was time to make a mounting ring. I could have just drilled a bunch of holes and used Nutserts, but that creates another set of problems with the raised heads, and the possibility of warping between the rivets and potential leaks. I wanted a nice clean seal, so this meant an inner ring strong enough to pull everything flat so I could use gasket material rather than a bunch of silicone for the seal.

This is what I came up with, from the top:

1. The inner ring, split so I could get it into the 4" opening.
2. The top ring.
3. The stamped recess from the GM tank that the pump assembly sits in.
4. The top portion of the GM pump mount. This was originally spot welded to the recessed portion. Drilling out the spot welds provided locations for the bolts I would use later to secure it to the new mounting ring. I added a few extra holes ensure a good seal.

This is a later picture after the key parts had been machined, drilled, tapped and gold-cad plated.

More later.

 

[diogenese]

It's a bit late now but you could have just done one cut on the inner ring and wound it into the tank, it might have made alignment a bit easier.

 

[RustyNailJustin]

I did this on one of my 45s a few years ago but with a Tacoma pump and am really happy with how quite it is and reliable.
Also the prefilter in tank is nice. If you wheel you can also invest in fuel mat for your prefilter, basically making a large area your pickup.

Looking good.

 

[reddingcruiser]

It's a bit late now but you could have just done one cut on the inner ring and wound it into the tank, it might have made alignment a bit easier.

I actually did this during the prototype phase and found that I had to remove a large portion of the circle to 'roll' ring into the tank. The split is easy to install, and I expect to do this just once.

 

[reddingcruiser]

In an earlier version of the fuel pump assembly I tried to work with the existing fuel inlet and outlet by bending them to the angles I needed to clear the underside of the seat. No bueno!

Compression couplings and steel tubing worked much better. Silver soldering was an option and I had used it on an earlier attempt, but the compression couplings gave me some adjustability to the return tube that the pump rests on, so I used them for all of the connections.

Next came a dry run of all the parts together. The ends are offset to allow for AN 90's if I want to go that route. The fuel fill overflow and vent tube connections are silver soldered in place as are the AN fittings.

The one interference issue I had no matter where I placed the pump assembly was with the fuel gauge sending unit. The fix was easy. I bent the bottom end of the float arm 180º to clear the pump. It has just enough room to clear the right side baffle.

Here's the tank just back from the powder coater with everything sitting in the tank.

 

[reddingcruiser]

The next project is to work on a baffle tray or use a fuel mat. I've mocked up a tray, the challenge is it has to fit through the 4" hole, which means it will need to be installed in sections. Here's the mock up. Obviously it doesn't need to be liquid tight since the object is to fuel to flow into it. It only needs to retain enough fuel to supply the engine when driving uphill and downhill at extreme angles. The return line dumps into this space and helps keep fuel at the base of the pump.

As I mentioned previously, I never had a fuel starvation issue with the stock FJ40 fuel pick up location, which is on the bottom left side of the tank. This should only improve the situation.

 

[78fj40mg]

In an earlier version of the fuel pump assembly I tried to work with the existing fuel inlet and outlet by bending them to the angles I needed to clear the underside of the seat. No bueno!

View attachment 1235896

Compression couplings and steel tubing worked much better. Silver soldering was an option and I had used it on an earlier attempt, but the compression couplings gave me some adjustability to the return tube that the pump rests on, so I used them for all of the connections.


View attachment 1235899

Next came a dry run of all the parts together. The ends are offset to allow for AN 90's if I want to go that route. The fuel fill overflow and vent tube connections are silver soldered in place as are the AN fittings.

View attachment 1235908

The one interference issue I had no matter where I placed the pump assembly was with the fuel gauge sending unit. The fix was easy. I bent the bottom end of the float arm 180º to clear the pump. It has just enough room to clear the right side baffle.

Here's the tank just back from the powder coater with everything sitting in the tank.

View attachment 1235910

View attachment 1235915

Very nice work Dick! Thanks for sharing!

 

[Coolerman]

Are you sure you own a Land Cruiser? Land Cruiser owners work benches are NEVER that clean!

That is some good work on that pump system.

 

[Tools R Us]

We used parts off of an FZJ80, welded into the FJ40 tank. Made baffle parts and pop-riveted them into the existing structure.

 

[Weber Sarge]

Just fyi - if you like those Wiha screw drivers , try out the KTC or Vessel JIS series drivers for Japanese industrial cross heads - you'll want to throw away every Phillips you own...
Interesting in-tank pump setup , good ideas there .
Sarge

 

[mdsims]

Good work ReddingCruiser. Question, what LPH flow rate is that pump? Do you anticipate being able to hear it run? I'd imagine that most of the sound will be drowned out by the engine and road noise. Just wondering as I have run walbro 190 & 255s on a modified Tacoma and I could hear that pump from the driver seat if I had the window rolled down. I don't recall ever hearing the OEM pump, so perhaps that loud operation is mainly an issue with the high flow models?

Otherwise, great work here, very thoughtful approach.

 

[reddingcruiser]

My 5.7L TBI uses the 12 psi/20 gpm pump. I am hoping to not hear the pump when it's in the tank. Right now it drives me crazy when driving around town. On the highway you don't notice the buzzing with all the other noise an FJ4o makes at 65 mph. Time will tell. Hopefully I'll finish the tank this weekend and get it in the following weekend.

 

[sadam_husain]

nice work mate (and Tools R Us) you wont ever regret shifting the pump into the tank where its supposed to be

 

[Norseman66]

Has anyone installed an in the tank pump in a 22 Gallon Con Fer aux tank?