Lycoming O-360-A1A engine driven fuel pump question:

How much fuel should be flowing from the outflow end of the pump? I am chasing a possible fuel restriction and when we disconnect the hose from the discharge side, it is a weak flow at best. Certainly not race horse flow as would be expected. Different airplane, same set up and similar results. At this point I’m thinking the flow rate is normal but wanted to see if any Mensa members here had a different opinion.

Only looking for info about the question I asked...and of course this is only for those of you that has flown a 170 with Wing-X.
Everyone else can go _ _ _ _ themselves

Cheers

So, how are you driving the pump? And at what rpm?

The pump, being engine driven, moves fuel at appropriate volumes, based on engine rpm.

Frankly, I think a better measure of pump health would be to measure pressure, as opposed to volume.

MTV

After talking with you earlier tonight, it is an interesting issue.

Say your engine driven pump goes TU. It is apparently now an obstruction in the fuel supply due to its inability to bypass fuel at the inlet pressure you'd expect from just head pressure in a gravity-fed system. A pump that's not being driven is constricting flow, or so I have observed inferred.

I have a 175 with an O-360A1A. Many (including myeself) have gotten rid of the fuel pumps (both mechanical and electric) all together. They are simply not needed in the high wing airplanes. There are tons of hem field approved to remove the pumps and install a 7/16 fuel line/fittings from the fuel valve forward. It was a no brainer for me, no pumps to maintain, less plumbing (and fittings to leak), less weight, no wiring
/switches/circuit breaker or fuel pressure gauge.

For my own little experiment even before I put the larger fuel line on, I disconnected the fuel line from the gascolator and flipped on my engine monitor and opened the fuel valve, right down to the last gallon in either wing over 24gph worth of fuel flow is being supplied to the carburetor. Straight out full throttle 2700rpm at sea level density I am burning a hair over 16gph, although usually on climb out I am seeing right about 15+/- .5.

Newbizor wrote:I have a 175 with an O-360A1A. Many (including myeself) have gotten rid of the fuel pumps (both mechanical and electric) all together. They are simply not needed in the high wing airplanes. There are tons of hem field approved to remove the pumps and install a 7/16 fuel line/fittings from the fuel valve forward. It was a no brainer for me, no pumps to maintain, less plumbing (and fittings to leak), less weight, no wiring
/switches/circuit breaker or fuel pressure gauge.

For my own little experiment even before I put the larger fuel line on, I disconnected the fuel line from the gascolator and flipped on my engine monitor and opened the fuel valve, right down to the last gallon in either wing over 24gph worth of fuel flow is being supplied to the carburetor. Straight out full throttle 2700rpm at sea level density I am burning a hair over 16gph, although usually on climb out I am seeing right about 15+/- .5.

Interesting. I have an Avon converted 175 with O-360 A1A, still equipped with fuel pumps. My engine, at ~ 5000 plus DA shows well over 18 gph at max power.

I’ve thought about removing the pumps on this and a 170 I owned with same Alcon conversion, but can’t really see the cost/benefit making it worth the $$$. Perhaps if I were installing this mod.....but at that point, I’d be so deep into bank accounts......

But to start off removing all that stuff, installing a new fuel line is a lot of messing around for minimal benefit, it seems to me. Unless you’re an A and P I suppose.

And, Zane, potential failure of the engine driven pump is the reason these STCs require an electric backup pump.

MTV

Great responses. I certainly like the idea of removing unnecessary items. Cost would be reasonable for the benefit IMO.
180 hp cubs don’t have any of that stuff and they seem to be working just fine.

akgreg wrote:Great responses. I certainly like the idea of removing unnecessary items. Cost would be reasonable for the benefit IMO.
180 hp cubs don’t have any of that stuff and they seem to be working just fine.

No doubt it’ll work. But cost to benefit? How many hours of labor would you guess?

Not arguing, just curious if someone has had this done and knows the approximate number of hours to do?

MTV

My mechanic loves hugs and unicorn t-shirts. I figure two of each should take care of it.

I too, have a C175 with O 360A1A, and have both fuel pumps. Didn’t know there was any option for removing them. The larger fuel line from the selector forward would be a pretty easy job. Who has an STC?
Dave

Dave,

As far as I know, there are no STCs. There are a number of these field approved.

MTV