Lift pump pressure monitor

[Lug]

Just had another lift pump quit, one year after install. What methods have others built to monitor the lift pump pressure and operation?
Justin

[HH]

I have an LED light so I know it is getting power, and then listen for it to run, either when starting or at shutdown. Make sure it is not your OPS unit.

[Lug]

New oil pressure switch that now runs another pump relay. The Racor filter head has two outlet taps so I have been plumbing a direct reading vacuum/pressure gauge in for troubleshooting. Would like a more permanent set up. An idiot light that comes on when there is a slight vacuum would be great. HH how do ypu have your power indicator LED wired?
Justin

[DennisG01]

Lug - I haven't done this myself, but couldn't you just install an electrical fuel gauge? Something like a 0-15psi? The gauge head can be mounted anywhere you want.

[Lug]

The gauge was my original idea, but then I started to price them out locally. Also a big bright light gives an immediate warning whereas the gauge has to be included in a scan and you know how hard it is to keep an eye on the gauges when cruising around AK? Especially during tourist/fishing season on the Seward and Sterling Highways.
Justin

[DennisG01]

Sure - if you're just looking for a basic "is it or isn't it working" thing, then a light is great idea. In that case, maybe just use a pressure switch with the appropriate psi rating that you'll be concerned about. I don't know what PSI you'll see at the LP - it might be hard to find a switch with a low enough rating. A few years back, I did something similar for engine oil pressure - a bright red light mounted on dash that only comes on at about 12 or 15psi and below.

[HH]

HH how do ypu have your power indicator LED wired?
Justin

I just tapped in at the fuse under the hood. It does not get power until the oil pressure comes up or the relay powers. But all that is telling me that voltage is going to the pump.

[Lug]

Another idea that we use in aircraft is to use a relay to sense current flow in the circuit to turn on the light. The downside to that is that it adds another component in series with the pump (or other component) that can fail and shut things down.
Justin

[Lug]

Just finished installing my fuel pressure light. Hobbs (Honeywell) pressure switch 2 psi, red 12 volt led from Radio Shack, and some wiring mods and a successful test drive. I used the old boost solenoid wiring and spliced new wires to the engine end to reach the pressure switch. Then unpinned the yellow wire from the pcm. Be careful because the factory wiring manual for the 94 has the wrong pcm plug called out on the schematic and the pin chart is mislabled. A couple of short runs to the led and viola a new idiot light on the dashboard. 2 psi switch does activate the led under hard acceleration so it almost acts like a wasting fuel reminder. Next mod might have to be one of the Walbro pumps.
Justin

[DennisG01]

Perfect! Thanks for posting your results. Was it hard to find the pressure switch?

[Lug]

Got the pressure switch from Reeve's Airmotive at Merrill Field. He ordered it up from Aviall. Probably cheaper suppliers then an aviation parts house, but I knew that was an almost sure bet because airplanes have Hobbs hour meters. The part number switch I used, if interested, is the 76061 which has two screw terminals and is a normally closed switch. The red led part number from Rad. Shack is 276-0270.
Justin