Robert Sailor
Well Known Member
So this issue has been going on for a long time and I want to solve it. I have an IO-320 Lycoming with 500+ hours. I purchased the aircraft 4 years ago and for the first year or so everything operated perfectly except the fuel flow transducer which I replaced.
As soon as I started long cross countries my current problem showed itself. I live on the Westcoast and unless I’m flying locally I’m climbing between 10-12000 feet. During this climb at high altitudes or more commonly when I reach cruising altitude and my cylinder head temps are hot, oil is hot and I start leaning more aggressively and reducing rpm my fuel pressure starts to drop. Normal pressure is about 23-25 lbs and it starts to drop to 10-12 lbs or even less. My EFIS alerts me and I throw on the electric boost pump, leave it on for a few minutes and my problem goes away only to return later or it may run for several hours with no issues. When I put on the boost pump the pressure rises immediately to about 28 lbs.
If I wasn’t over mountains I’d be tempted to leave the boost pump off to see what happens as the engine has never stumbled or lost rpm.
I’ve seen pressure drop to 6 or 7 lbs before I got on it but even then it was running fine. The boost pump trick has so far solved the issue BUT it shouldn’t be there.
My thoughts…it’s a mechanical engine driven pump, basically a diaphragm pump.
I had one fail on my Cessna 210 and it didn’t screw around, it failed, prop went full fine and I was pulled from my belts while I went through my normal sequence to get it running again….it’s what I imagine a diaphragm pump does at end of life.
So my friends say this….it’s a mechanical pump, it either works or it doesn’t.
They think the problem is with my transducer…I don’t buy into that, I of course agree that a mechanical pump usually works or it doesn’t however I don’t think there is anything wrong with the pressure transducer because when I hit the boost pump it immediately shows 28 lbs. if it was the transducer I’m sure it would show up when I turned the boost off and on, it doesn’t.
This situation is always associated with heat and higher altitude…..I’m stumped! Help me solve this if you can, id be very appreciative. Robert
As soon as I started long cross countries my current problem showed itself. I live on the Westcoast and unless I’m flying locally I’m climbing between 10-12000 feet. During this climb at high altitudes or more commonly when I reach cruising altitude and my cylinder head temps are hot, oil is hot and I start leaning more aggressively and reducing rpm my fuel pressure starts to drop. Normal pressure is about 23-25 lbs and it starts to drop to 10-12 lbs or even less. My EFIS alerts me and I throw on the electric boost pump, leave it on for a few minutes and my problem goes away only to return later or it may run for several hours with no issues. When I put on the boost pump the pressure rises immediately to about 28 lbs.
If I wasn’t over mountains I’d be tempted to leave the boost pump off to see what happens as the engine has never stumbled or lost rpm.
I’ve seen pressure drop to 6 or 7 lbs before I got on it but even then it was running fine. The boost pump trick has so far solved the issue BUT it shouldn’t be there.
My thoughts…it’s a mechanical engine driven pump, basically a diaphragm pump.
I had one fail on my Cessna 210 and it didn’t screw around, it failed, prop went full fine and I was pulled from my belts while I went through my normal sequence to get it running again….it’s what I imagine a diaphragm pump does at end of life.
So my friends say this….it’s a mechanical pump, it either works or it doesn’t.
They think the problem is with my transducer…I don’t buy into that, I of course agree that a mechanical pump usually works or it doesn’t however I don’t think there is anything wrong with the pressure transducer because when I hit the boost pump it immediately shows 28 lbs. if it was the transducer I’m sure it would show up when I turned the boost off and on, it doesn’t.
This situation is always associated with heat and higher altitude…..I’m stumped! Help me solve this if you can, id be very appreciative. Robert