Homebrew bypass/regulator valves:

In the past discussions related to added pusher pumps, and/or relocated Lift Pumps, it has become evident that while these mods are very helpful in better fuel flow and PSI, they also create a potential fuel blockage issue if they lose power or otherwise fail. That scenario often causes ALL fuel flow to be lost, with a resulting stalled engine due to fuel starvation.

Some of us have built and installed bypass valves and lines around these pumps to allow fuel flow even if the pump has failed ‑ some guys do this with manual ball valves, some. like me, use an automated valve that will change fuel flow automatically, with no manual action needed.

Here's an example of one of mine:



There's been some interest in exactly how these are made, so I decided to make one up out of relatively common ACE hardware store items for guys interested.

Here's a blown‑up shot of an easily constructed bypass valve made with ordinary and inexpensive components ‑ a 3/8 in close pipe nipple, 2 3/8 inch brass hose barb fittings, a spring, and a common 1/4 inch or so steel ball bearing:



The barb fitting at the top of that pic looking down inside is to show the seat that the ball bearing seats against when normal fuel flow is present, which closes off fuel flow from the pump output back to it's imput. The spring shown fits loosely inside the pipe nipple, and is only there to prevent the bearing from moving to the opposite end, and closing that end off ‑ the bearing has about 1/2 inch of free travel in this particular design.

Here's that valve in finished and assembled form:



If you apply fuel flow, or simply blow into one end, you get full flow ‑ blowing into the opposite end causes the bearing to seat, and completely blocks flow ‑ all automatically!

NOW, for guys needing a regulator for higher powered pumps like the Walbro with more flow and PSI, here's a homemade valve for that purpose:



In this example, you will see a 1/4 inch stainless steel acorn nut with a 1/4 inch threaded bolt section installed into it ‑ both are then inserted into a commonly available spring selected for this application. On the other side of the 3/8 inch close nipple, you see several 1/4 inch stainless washers ‑ these are shims used to adjust the pressure on the spring, and that of the head of the acorn nut against the surface of the T fitting next to it to the left. This particular setup will provide regulated fuel flow of about 20 PSI ‑ other fuel pressures can be obtained with different springs and/or shims.

If you want to combine BOTH a bypass AND a regulator all in a single assemby, no problem!



The above setup will provide about 20 PSI regulated fuel flow, AND will AUTOMATICALLY open up to allow full fuel flow to bypass the setup if the pump fails!

The finished assembly looks like this:



These setups are easily made ‑ I use JB Weld to seal the various threaded components together, since they require a mix of pipe and compression thread fittings, but that has been no problem, and no leaks to date. These are quick and easy to make, and are very inexpensive ‑ the most elaborate one was about $20 in parts, and is well suited to a Walbro pump ‑ which I just happen to have waiting to be installed on my own truck...

Here's a shot of just the bypass valve installed on a Walbro pump:



ENJOY!