An economical alternative to Holley Hydramat
For the fuel cell in Tom’s RX7, we were concerned about being able to pick up fuel when cornering. The fuel pick-up is in one corner of the tank so any slosh will uncover it.
After some research, I found these Walbro fuel pucks designed for snowmobiles. They come in a few varieties: single connection double connection and a right angle connection. Some come with vent holes.
You need at least one with a vent hole because if the system ever runs completely dry, the membrane will seal up and not reopen until the vacuum is released. The vent hole releases the vacuum without any action required.
I ordered four pucks. One 90-degree to go under the original pick-up point, two of the two ways, and a single with a vent hole for the end of the line. I also got some rubber hose rated for being submerged in fuel to connect the pucks,
I ordered it all from http://autoperformanceengineering.com/. The pucks are also available from Amazon. https://amzn.to/3djar0M.
The pucks have 5/16 fittings so the connector hoses are 5/16. I got a 5/16 to 1/2 adapter to make the connection to the fitting in the top of the fuel cell. I got some 5/16 copper tubing to make the runs between pucks.
Directly below the original pickup, I placed the MP-16. I then bent a piece of copper to place the next puck in the rear corner. I used an MP-14 here. I then made another run of copper to the other rear corner and attached another MP-14. I then ran the line to the front corner and installed the MP-13 to finish the line.
I was able to assemble the whole system above the tank and then feed it through the filler opening in the fuel cell. The most difficult task was getting the AN8 fitting connected to the bulkhead fitting as I made the clearance tight so the puck would sit on the bottom of the tank when installed.
Once we get everything working, (the fuel pump needs to be replaced) I will give it a go at pumping until it runs dry and see how much fuel is left in the tank,