Given the clean fuel we normally have, this modification is in the “nice to have but not required” category. Racor sells a vacuum gauge that replaces the T handle. The gauge shows the vacuum that the lift pump uses to pull fuel through the Racor. As the filter clogs, the vacuum increases. However, our Racors are located in the lazarette and if the fuel filter is starting to clog, it will show first at higher RPMs, not a time when anyone can easily check the T-Handle vacuum gauge.
The solution is to put the vacuum gauge at the helm. Racor sells a gauge (RK11233) which I installed in the empty gauge location on my Cummins instrument panel. You can find the kit in the West catalogue as a “Spin-on Fuel Filter Vacuum Gauge.”
Locate the fuel line which runs from the outlet side of the Racor to the lift pump. Cut it in the vicinity of the left rear engine mount and install a T fitting with hose barbs. The flow to the engine goes through the top of the T and the vacuum gauge hose to the helm goes on the stem of the T. The reason to install the T in this location is that the hose to the gauge should be limited in length and on a NT-32, the run to the helm from this location is within the Racor specified length while a run from the lazarette would be too long.
To be on the safe side, I put a valve in the vacuum line hose near the T so that if the gauge were to break or develop an air leak, I can shut the valve and keep air out of the fuel system. Also, be sure to protect the fuel hose and the vacuum hose from chafe.
You can check the gauge for proper operation by having someone briefly close the fuel shut off valve (with the engine running) in the lazarette while you observe the gauge. The vacuum will rise dramatically.
I find that if I change my filter once a year, the vacuum never rises. However, if an algae problem were to develop and begin to clog the filter, I would know about it long before the filter clogged, shutting off the engine at an inopportune time.
Jim & Mim McCrea
North Star – NT 32-154