Flight foiled by aux fuel pump

[cgrab]

The Facts: 1968 Cardinal, O-320 150 hp with mogas STC, Temp about 30F after 20s overnight.

Yesterday I cancelled a flight after turning on the master, then the Aux Fuel pump; it clicked a couple times then stopped. The pressure gage went up to 8 the to 0. I checked the circuit breaker and it was in. I put the plane away and drove to my meeting instead.
There was no water when I sumped the tanks but it could have gotten into the pump which is at the bottom of the system and frozen.

I'm wondering if when I go back when it is warmer, can I expect different results or should I be looking for a new pump?

 

[coloradobluesky]

I wouldn't replace the pump without eliminating that it could be frozen water. If its frozen water, you want to know about that because it could happen again.

 

[flyingron]

If you got frozen water in the pump, there's a good chance it was damaged as well. If ice just accumulated in a screen you may be ok.

I'd be looking carefully at the pump in either situation.

 

[frfly172]

If you have a sump for the pump,try sumping the pump,look for water,when the temperature is warmer.

 

[cgrab]

Thanks, I'll go out tomorrow and turn it on. If nothing then "off with their cowls" and I'll pull it apart. It sits on the front of the firewall and I'll just need to replace the safety wire which I think is allowed.
There is no drain in the pump.

 

[bnt83]

I keep wondering when my pump is going to take a dump. It is 47 years old.


They make a hammering noises when dry

 

[bnt83]

Thanks, I'll go out tomorrow and turn it on. If nothing then "off with their cowls" and I'll pull it apart. It sits on the front of the firewall and I'll just need to replace the safety wire which I think is allowed.
There is no drain in the pump.

There's a cap on the end and you need around a 1" wrench to get it off. In there is a screen, big rubber washer and a magnet.

MAKE SURE you remove the fuel selector knob then turn the valve to the unplacarded "OFF" position before trying it.

Firewall shutoff valves tend to leak by in the "OFF" position.

 

[cgrab]

My pump has a cap with a nipple and slot (no need for a wrench). I have had good luck with my fuel shutoff. We check it every year.

 

[bnt83]

Could be a low battery too. Easy to check before messing with anything else. Also easy to check the voltage on the load side of the switch, maybe the switch didn't make good contact.

 

[cgrab]

Thanks, I'll check the switch. Easy enough to do.

 

[James331]

Get some wire and start jumping stuff.

Can you see any drain on your electrical when you turn it on?

I had my boost pump just about have me convinced it was dead, turned out to be a screwed breaker, it was in but the pump wouldn't go on, wiggle it enough and sure enough the pump kicked over, lot cheaper than a new switch and way cheaper than a new boost pump.

 

[bnt83]

Get some wire and start jumping stuff.

Can you see any drain on your electrical when you turn it on?

I had my boost pump just about have me convinced it was dead, turned out to be a screwed breaker, it was in but the pump wouldn't go on, wiggle it enough and sure enough the pump kicked over, lot cheaper than a new switch and way cheaper than a new boost pump.

His and mine have "solid state interrupter" type pump, not a rotary. There are ring terminals on each switch making jumping super easy. The switches are basically impossible to replace but it is possible to get the back off the switch and clean the contacts.

 

[steingar]

Why does a high wing airplane need a fuel pump? I actually flew around for a year or two with a busted aux in my old Cherokee. Just didn't know any better.

 

[bnt83]

Why does a high wing airplane need a fuel pump? I actually flew around for a year or two with a busted aux in my old Cherokee. Just didn't know any better.

Because somewhere in CAR3 / Part 23 it says that gravity feed airplanes need ____ PSI (>0.5 IRRC) head pressure at the carburetor inlet during normal flying attitudes. The Cardinal doesn't during climbing attitudes.

 

[cgrab]

So I went by the airport on the way home last night and checked the switch for continuity. The switch is working so tomorrow I'll put power to the pump from a battery and see if it is the pump or the wiring.