Piper fuel pump usage/overusage?

alfadog

alfadog

Final Approach
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alfadog
My Arrow has an electric fuel pump (guess they all do) and I turn it on for takeoff and landing. Or at least most of the time I do. I sometimes forget if I am doing pattern work though I am getting better at my checklists and GUMPS checks during pattern work.

But I have a bit of an aversion to running it longer than absolutely necessary. This probably comes from the many fuel injected 1970's-era Alfa Romeos I have owned and the numerous fuel pump problems I have experienced.

My thinking is twofold:

1. Fuel pump has a life span and I will get more time between pumps if I limit usage.
2. Fuel pumps get hot and that severely shortens life span.

Obviously, the first is true but what about the second? Do y'all limit the amount of time you run the pump. I do not turn the pump on until around 1000' AGL on landing and turn it off at 600' on takeoff.

What do y'all do?
 
I go by the POH checklist and yes, they do burn out prematurely if you run them constantly.

Note however, Turbo Arrows are equipped with a two speed electric fuel pump, but it isn't used in normal operation. It's just to control vapor lock if it occurs.
 
Fuel pumps don't 'get hot', if they do they are defective and dangerous. I'd be more concerned with switching issues, ie if I was staying in the pattern, I'd just leave it on.
 
On our Arrows I keep it on until climb out during takeoff and turn it on before my Before Landing Check. Sometimes I have caught myself with it off at the PUFFS check on short final. If we are doing maneuvers then it is on for the entire flight since our practice area is so close. I don't think we have ever replaced the pumps since we got the aircraft in '06.
 
Sac Arrow said:
I go by the POH checklist and yes, they do burn out prematurely if you run them constantly.

Note however, Turbo Arrows are equipped with a two speed electric fuel pump, but it isn't used in normal operation. It's just to control vapor lock if it occurs.
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Turbo Arrow is a Continental FI system which is very different from the Bendix system on the Lycoming in the Arrow. The low side of the switch is the boost pump as you indicate, the high side of the switch is an emergency pump to keep the engine running if the FI pump fails.
 
Henning said:
Fuel pumps don't 'get hot', if they do they are defective and dangerous. I'd be more concerned with switching issues, ie if I was staying in the pattern, I'd just leave it on.
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How do you know this? Any electric motor gets hot (warm) when running. How hot can vary and certainly the fuel flow cools the motor but I would be rather surprised if it is not warmer after 60 minutes running than it is after 10.
 
steingar said:
Had to replace mine once, thus I am fairly cagey about its use.
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If you've already replaced it once, you will probably see a shorter service life from it by being sparing than letting it run a few extra minutes a flight. The worst thing on a machine is inactivity.
 
I leave it on until I am at 1,500 ft AGL, and turn it on a few miles out from entering the pattern.

I replaced one also several years ago.
 
You don't 'need' to turn the pump on unless the engine dies. Even at 14,500 I never had vapor lock issues in the Arrow. There is even a chance depending on the mode of the engine driven pump failure that the electric back up/boost pump won't do any good anyway. personally I don't use them for landing unless I have a reason to suspect a problem. It takes less than half a second to punch that switch if the engine stutters.
 
Which variant Arrow, which engine? Carburated or injected?

I know that with the Warriors, the electric fuel pump is there to put a little extra pressure in the system and as a backup if the fuel driven pump fails. It's used on takeoff, climb and landing...perhaps because with a slight up angle, you're making the pump push fuel just a little higher than in cruise.

I think the physics of that are the same for the Arrow.
 
I was recently asked if leaving the fuel pump on had any dangers associated with it. All I have ever heard of us plug fouling due to creating an over rich situation. The individual asked about pressure, and if the increased pressure over a long period of time could cause problems. I don't think so because people forget, and leave them on all the time. Is there a pressure relief valve soemwhere or is it just not enough additional pressure to over stress the system?
 
bflynn said:
Which variant Arrow, which engine? Carburated or injected?

I know that with the Warriors, the electric fuel pump is there to put a little extra pressure in the system and as a backup if the fuel driven pump fails. It's used on takeoff, climb and landing...perhaps because with a slight up angle, you're making the pump push fuel just a little higher than in cruise.

I think the physics of that are the same for the Arrow.
Click to expand...

I thought all Arrows were FI? Anyway, Arrow II; IO-360-C1C. I think it is simply there in case the mechanical pump fails; you put it on as a precaution.
 
bflynn said:
Which variant Arrow, which engine? Carburated or injected?
Click to expand...

All Arrows had fuel injected engines.

bflynn said:
I know that with the Warriors, the electric fuel pump is there to put a little extra pressure in the system and as a backup if the fuel driven pump fails. It's used on takeoff, climb and landing...perhaps because with a slight up angle, you're making the pump push fuel just a little higher than in cruise.

I think the physics of that are the same for the Arrow.
Click to expand...

The electric fuel pump is there in case of the engine driven fuel pump failure.
 
Interesting. Thanks. Didn't know that.
 
Anthony said:
I was recently asked if leaving the fuel pump on had any dangers associated with it. All I have ever heard of us plug fouling due to creating an over rich situation. The individual asked about pressure, and if the increased pressure over a long period of time could cause problems. I don't think so because people forget, and leave them on all the time. Is there a pressure relief valve soemwhere or is it just not enough additional pressure to over stress the system?
Click to expand...

I don't think the fuel pump increases the fuel flow. Regardless, you will either lean with it on, or you will have turned it off before you lean. I don't think leaving the fuel pump on causes any other problems beside increased wear and tear on the fuel pump.
 
Didn't read through all the posts but the pump is rated for continuous use, it's a Facet automotive pump that I think some folks like to put on hot rods. They go bad, I lost one about a year ago, be glad you have two. Any pattern work, it stays on all the time, forgetting to turn it off isn't an issue. Just make sure you're fuel pressure is good, too high can be bad too, espeically if you're running full rich in the pattern. I usually flick mine off when I get to 1500-2000' AGL.
 
bartmc said:
Didn't read through all the posts but the pump is rated for continuous use, it's a Facet automotive pump that I think some folks like to put on hot rods. They go bad, I lost one about a year ago, be glad you have two. Any pattern work, it stays on all the time, forgetting to turn it off isn't an issue. Just make sure you're fuel pressure is good, too high can be bad too, espeically if you're running full rich in the pattern. I usually flick mine off when I get to 1500-2000' AGL.
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It looks to be a Weldon pump. P/N 8120-G; Piper P/N 67881-05. Lists for maybe $1k and cheapest is almost $700. Not a cheap part or one I want to burn out prematurely. The Facet pumps are cheap, the Weldon pumps are expensive. :sad:
 
alfadog said:
It looks to be a Weldon pump. P/N 8120-G; Piper P/N 67881-05. Lists for maybe $1k and cheapest is almost $700. Not a cheap part or one I want to burn out prematurely. The Facet pumps are cheap, the Weldon pumps are expensive. :sad:
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I'd rather burn a pump than have 1000' in a PA28 to debug the problem and get the engine started. I can't imagine the Weldon not being rated for continuous use. I either leave mine on or off. always on in the pattern, always off not in the pattern. I figure flicking it off and on does more harm that leaving it on for a couple of hours.
 
bartmc said:
I'd rather burn a pump than have 1000' in a PA28 to debug the problem and get the engine started. I can't imagine the Weldon not being rated for continuous use. I either leave mine on or off. always on in the pattern, always off not in the pattern. I figure flicking it off and on does more harm that leaving it on for a couple of hours.
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Yes, I am leaning (LOL, a fuel joke) now toward leaving it on below 1500' so that would cover all pattern work.
 
bartmc said:
I'd rather burn a pump than have 1000' in a PA28 to debug the problem and get the engine started. I can't imagine the Weldon not being rated for continuous use. I either leave mine on or off. always on in the pattern, always off not in the pattern. I figure flicking it off and on does more harm that leaving it on for a couple of hours.
Click to expand...

Yep, if you're going to be in the pattern, just leave it on. Just don't forget to turn it off before you park so you know you still have a working mechanical pump.
 
On my old E30 and my E46 (BMWs), the fuel pump is lubricated and cooled via the fuel flowing through it.
 
If we're talking about the carbureted Lycoming Cherokees I leave the fuel pump on the entire time in the pattern and teach my students to do the same.

If I'm on tower frequency the pump is on. When I switch to departure it gets turned off.

Don't confuse the fuel pump usage with the injected birds. Different beast.
 
jesse said:
If we're talking about the carbureted Lycoming Cherokees I leave the fuel pump on the entire time in the pattern and teach my students to do the same.

If I'm on tower frequency the pump is on. When I switch to departure it gets turned off.

Don't confuse the fuel pump usage with the injected birds. Different beast.
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Lycoming/Bendix system, aux pump works same same as carb engine. Continental FI system Low is same, High is a pump that should run the engine should the injector pump fail.
 
Anthony said:
... The individual asked about pressure, and if the increased pressure over a long period of time could cause problems. I don't think so because people forget, and leave them on all the time. Is there a pressure relief valve soemwhere or is it just not enough additional pressure to over stress the system?
Click to expand...

How much additional pressure are you getting?

Try this: Fly normal cruise speed and altitude, electric pump off. Note fuel pressure reading on the gauge. Turn on electric fuel pump. Note pressure reading on gauge.

Is there a significant difference? On an Archer, the answer is no. Yes, Comtinental is different from Lycoming.

-Skip
 
Henning said:
Yep, if you're going to be in the pattern, just leave it on. Just don't forget to turn it off before you park so you know you still have a working mechanical pump.
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The 421 will tell you if you forget to turn off the pumps, the engines will diesel when you go to idle cut off.:mad2: the line guys will laugh at you.:mad2:
 
Skip Miller said:
How much additional pressure are you getting?

Try this: Fly normal cruise speed and altitude, electric pump off. Note fuel pressure reading on the gauge. Turn on electric fuel pump. Note pressure reading on gauge.

Is there a significant difference? On an Archer, the answer is no. Yes, Comtinental is different from Lycoming.

-Skip
Click to expand...

I don't think I've ever actually used the boost pump on the Turbo Arrow so I don't know. In the Arrow II, no difference.
 
N747JB said:
The 421 will tell you if you forget to turn off the pumps, the engines will diesel when you go to idle cut off.:mad2: the line guys will laugh at you.:mad2:
Click to expand...

On low? Doesn't seem right, in fact, the 310 doesn't have a 'low' anymore because there's an AD that has them on full time. 'High' most definitely it'll do that, but it's supposed to.
 
Henning said:
Turbo Arrow is a Continental FI system which is very different from the Bendix system on the Lycoming in the Arrow. The low side of the switch is the boost pump as you indicate, the high side of the switch is an emergency pump to keep the engine running if the FI pump fails.
Click to expand...

Or in one of my more memorable Turbo Arrow incidents, to keep the engine running if you suspect the engine-driven pump is failing due to low fuel pressure readings, but in reality it's working great and a leaky fuel totalizer fitting is spraying most of the fuel all over the turbo exhaust.
 
pericynthion said:
Or in one of my more memorable Turbo Arrow incidents, to keep the engine running if you suspect the engine-driven pump is failing due to low fuel pressure readings, but in reality it's working great and a leaky fuel totalizer fitting is spraying most of the fuel all over the turbo exhaust.
Click to expand...

Nice....
 
I believe the handbook for the PA-28-201 has you use the electric pump to change tanks too. Could be nice to have on if there is a vapor bubble in the lines when you switch over.
 
Skip Miller said:
How much additional pressure are you getting?

Try this: Fly normal cruise speed and altitude, electric pump off. Note fuel pressure reading on the gauge. Turn on electric fuel pump. Note pressure reading on gauge.

Is there a significant difference? On an Archer, the answer is no. Yes, Comtinental is different from Lycoming.

-Skip
Click to expand...

My Tiger has a Lyc. O-360A4K. The fuel pressure goes up slightly when I turn it on. That is a good sign it is working as you can't hear it over the engine noise. You see the needle move a bit to higher fuel pressure.
 
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