Let's Talk EFI Fuel Delivery

[mattanonymous]

My original plan for the KA swap was to do the Honda Civic pump, catch can, and sending unit grafting (via welding) that spriso pioneered. However, charlee0620 got me thinking when he suggested going with PA2 or PA4 from here. It contains the pump, mount, and catch can all in one and requires only cutting (aside from the mounting ring). There's a separate sending unit from the company here.

Both of those options are return-style and have the pump separate from the sending unit. That led me to check if there's a readily available (OEM) combination pump and sending unit. There is! It actually seems like they're quite popular in later model cars. They also appear to include a type of catch can as well. Here's an example.

Before I go down the path of finding one that fits and has the correct pressures, I wanted to get buy-in from the group.

I was also wondering if it would be easy to convert to a returnless style to remove the need for the return line. Is it as simple as getting a pump with the right pressure and capping off the rail's return?

[fj20spl311]

As you found out, there are lots of OEM units that can be adapted. Its also very popular to use one of the aftermarket add-on units like the ones from "Tanks Inc." Almost all the units have fuel pressure in the correct range, so they can be controlled by the fuel pressure regulator.

I would not try to adapt a returnless style because they don't bleed off any air that gets sucked up in the system. I also have concern about controlling the fuel pressure. Most of the older systems use vacuum on the fuel pressure regulator to reduce the pressure under high vacuum...this is not how its done on a returnless system.

If you have an early car, just use the original line as the return and plump a new line from your added fuel pump.

[spriso]

You're going to want a EFI pump with a return for your KA24DE (which in many ways is similar to a SR20DE/T).

On our 510 swaps with the SR we put in Aeromotive in-tank fuel pumps which work brilliantly and do not require welding.

https://www.aeromotiveinc.com/product/p ... el-system/

We find that the Aeromotive system is just a touch too tall for the roadster tank-- but there are other weld free pumps of a similar design out there, but we have not found the perfect application to work in the barely 6" deep roadster tank.

Our go-to solution is still to go with a weld-in Honda Civic application, but do so with EXTREME CAUTION and leave that kind of work to the experts-- this is not a backyard conversion.

Michael

[bobd]

I've had the tanks.com set up for a while now and it still works fine.

[mattanonymous]

Thanks for the input. I guess if the Civic setup is still good enough for spriso's builds, it's good enough for me. Sometimes I get stuck on a small part of the project and this seems to be one of those times haha.

[spriso]

The Civic option works well for us because I can easily modify the tank-- the no-weld option looks great if you can find a pump that can be configured short enough (like the Tanks inc. pump listed above).

[Teesun68]

All..Doing KA 24DE swap..on the topic of fuel delivery, planning to go with Civic option and roadster tank mod as per Michael S. - what is the direction on the tank vent? Is using the standard roadster vent tube plumbed to the filler neck sufficient solution or does one need to do something with the grafted civic "bits"?

Thanks..Michael
68 1600 "under mods"
1990 XJS

[Mattk]

So I guess I should chime in here since I’m part of the reason for the wavering.

BDB6B8BC-8FF0-4A7D-9E0C-B8703B3128A6.jpeg

I have two of the OEM pumps. I have looked at them and found that adapting either would be difficult, not impossible, but not as easy as the PA pumps. I also thought about the Spriso approach and it required to much welding. I’m not great at welding and know that the welds must be perfect as even a pin hole leak can be extremely dangerous if not deadly. I’ve looked and looked, as you have, and I’ve decided to go the PA because of ease of install and a reduction of potential leak paths. As for the sender, $35
seems reasonable and easy. Work smarter not harder is my approach.

As for the return, you should have it. As stated above it will help with air that is going to be sucked in to the system and helps assure a more steady flow of fuel.

Just a note there are other easy install in-tank systems, I’ve chosen the tanks inc one because it the one that makes sense to me. Also if the Walbro pump should fail, replacing it is easy. Just open up the tank and replace the pump not the tray assembly. Though Walbro pumps are pretty dependable and reasonably affordable.

If you choose a path that requires welding, please let a seasoned pro do the work, just for safety sake, that’s of course assuming that you are not great at welding like me.

Cheers
Matthew

[nismou20]

Charlee0620, so, your Pa approach does not require any welding whatsoever?

[2mAn]

I removed the smog line from my car so if someone wants a free hard line to use as a return, its here in SoCal for ya

[Mattk]

Charlee0620, so, your Pa approach does not require any welding whatsoever?

Nope! That and that it has a Walbro pump are why I’m planning on using it. You can weld the inside mounting ring/flange if you want, but not required. Just drilling/cutting holes for the pump/tray assembly and sender. Then drilling holes for the screws...in a boiled out clean tank of course!! All info at tanks.com. You do need a flat surface to mount the flange to! But our tanks have flats that accommodate that. I plan on cutting out the stock sender location to accommodate my pump and place the sender off to the side a bit.

Cheers
Matthew

[Teesun68]

Thanks for the insights everyone. I'll see how easily I can source the civic option - need to go visit a tank building shop and chat with them soon. No welding on a fuel tank for this dude...lol

[Burbach]

I found a complete Civic tank with parts - all in great shape for $120. My tank is rust free but this unit also seems to take up some space and may be an issue when the tank gets really low..
So here's a great alternative - the remote fuel sump pump.. Edelbrock has their version https://www.edelbrock.com/adjustable-un ... 36031.html
but the Hyperfuel version maintains an extra 1.5 liter sump which alone can help you hop to a gas station when in need.. Price isn't all that bad but the only issue I can see is finding a place to mount it.. I'm looking into that now. https://www.summitracing.com/parts/hpf-40004/overview/