Engine-driven fuel pump failure IO-320

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MacFly

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MacFly
This past weekend, I had what I presume is failure of the engine-driven fuel pump on my RV with IO-320 (engine was factory-new, now with about 400 hours). I was about 350 miles into a 500 mile flight. At the start of the flight, the engine had started and run fine, and all engine displays were in the green for the entire flight. Stopped for fuel and lunch, afterward the hot start went OK but running a little rough. I noted on the EFIS engine display that fuel pressure was solidly in the red at about 4-6 psi...not RPM-dependant. That was new. I taxied out planning to see what it did on runup and the engine died on taxi. I got it started...the pressure was still low... I hit the boost pump and it jumped into the green. Boost pump off...engine died.

I found a mechanic at a nearby airport, that had a fuel pump on the bench from an O-320 he was rebuilding. He switched it out...the engine ran smoother but fuel pressure was still in the red at 7 psi. Am I correct that the IO-320's have a higher pressure mechanical pump than the non-FI version of that engine?

The guy was nice enough to store the plane inside, ordered a fuel pump (same model as the one that failed - the higher pressure version) and will put it in on on Wednesday. We're presuming that the engine-driven pump died and the pump he tried replacing couldn't manage sufficient fuel pressure for a fuel-injected engine.

Opinions....? I'm under the impression that engine-driven fuel pump failures are kind of rare on these Lycomings but this plane had been hangared pretty much unflown for about a year. The fuel pressure gauge had been green the entire flight, until it wasn't after re-fueling and the engine died. Flipping on the boost pump put it back in the green immediately. Seems odd, but I can't think of any other fuel issue that would act that way except fuel pump failure. Other thoughts? Something I'm missing?
 
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I've replaced two of them on my carburated RV-6 in 19 years. The pumps have two thin rubber diaphragms inside that ultimately rupture.

Changing one can be a beeyotch. I'm 50/50 on that. The first one I did was a piece of cake. The second one didn't go nearly as well.
 
kyleb said:
I've replaced two of them on my carburated RV-6 in 19 years. The pumps have two thin rubber diaphragms inside that ultimately rupture.

Changing one can be a beeyotch. I'm 50/50 on that. The first one I did was a piece of cake. The second one didn't go nearly as well.
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Ain't that the truth? First of all it's tight quarters (I thought boats were bad), especially with a prop governor right there. But mainly, getting the angle between the pump and the firewall and being able to get the pump lever under the rod was very difficult. Ultimately, Dick the Mechanic did that by using some safety wire to pull the lever down so that he could slide the pump in with the pump lever under the rod and then snipping the wire after the pump was seated and almost-bolted down. Sadly, it was the wrong pump, but it was a good try and a great learning experience that, on Wednesday, should transform that 2 hour rodeo in to a 1/2 hour basic exercise when the new pump arrives.

Ya gotta love the small-town airport experience and the aviation community. When we couldn't get the plane flying, Dick the Mechanic loaned us his car to drive 4 hours north to get home, and on Wednesday we'll drive it 4 hours south the pick up the airplane and return the car.
 
Wouldn’t be talking about that in public if I hadn’t gotten a ferry permit to do it (which I doubt one would be issued)

The reply to your argument that it was only 12 miles would be, it’s only 12 miles, so not difficult to move the part and mechanic rather than the aircraft.
 
MacFly said:
Right. Thanks.

So, what do you think about the likelihood that there was an engine-driven fuel pump failure?
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In your case I’d say 100%. Not sure I understand the question.
 
MacFly said:
Ain't that the truth? First of all it's tight quarters (I thought boats were bad), especially with a prop governor right there. But mainly, getting the angle between the pump and the firewall and being able to get the pump lever under the rod was very difficult. Ultimately, Dick the Mechanic did that by using some safety wire to pull the lever down so that he could slide the pump in with the pump lever under the rod and then snipping the wire after the pump was seated and almost-bolted down. Sadly, it was the wrong pump, but it was a good try and a great learning experience that, on Wednesday, should transform that 2 hour rodeo in to a 1/2 hour basic exercise when the new pump arrives.

Ya gotta love the small-town airport experience and the aviation community. When we couldn't get the plane flying, Dick the Mechanic loaned us his car to drive 4 hours north to get home, and on Wednesday we'll drive it 4 hours south the pick up the airplane and return the car.
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Mechanic Dick probably did this, but another little helpful trick is to turn the engine so the cam drive is at the top of the stroke, then push the rod up into the bore and stick it there with a little grease.
 
Chip Sylverne said:
Mechanic Dick probably did this, but another little helpful trick is to turn the engine so the cam drive is at the top of the stroke, then push the rod up into the bore and stick it there with a little grease.
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We did turn the engine and do that, but even at the top of the stroke the rod hung down enough that the end of the lever hit it on the way in and there wasn't enough room between firewall and prop governor to angle it down. What Dick did was use some safety wire to pull the lever down enough to clear the rod, install the pump, clear the rod, and snip the wire before tightening the bolts down all the way. Putting grease on the rod to hold it in place is a great idea though, and I'll pass that on. Thanks!
 
Stewartb said:
Do you have an overflow tube on the mechanical fuel pump? It should be obvious when it fails. Potential diaphragm failure is why we run the electric pump for takeoffs and landings. I wouldn't hesitate to make a flight with my electric pump.
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Well, I definitely hesitated but did make the flight.
 
Why? Electric fuel pumps are rated for continuous duty. I have friends who have no accessory cases so no engine driven pumps. They do have dual electric pumps but have never needed to use the reserve pump.

I'd need to swing my engine to change my own pump. Not fun.
 
Do you have a warning annunciator for fuel pressure? My IO-390 FP range is 14-45 psi.
 
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Stewartb said:
Do you have a warning annunciator for fuel pressure? My IO-390 FP range is 14-45 psi.
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I have an AG6, and it did announce the low fuel pressure as I was taxiing out. I think by that time I'd already noted that the fuel pressure was low. It was a hot start, so boost pump wasn't running at startup.
 
Stewartb said:
Why? Electric fuel pumps are rated for continuous duty. I have friends who have no accessory cases so no engine driven pumps. They do have dual electric pumps but have never needed to use the reserve pump.

I'd need to swing my engine to change my own pump. Not fun.
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They aren't flying low wing aircraft either, I'd wager.
 
The spec is for servo inlet pressure. It doesn't specify where the tanks are.

I have a bad habit of forgetting to turn on my aux pump for takeoffs and landings. I need to add a pump status light to remind me.

MacFly, was your engine driven pump's dribble tube dribbling?
 
Stewartb said:
The spec is for servo inlet pressure. It doesn't specify where the tanks are.

I have a bad habit of forgetting to turn on my aux pump for takeoffs and landings. I need to add a pump status light to remind me.

MacFly, was your engine driven pump's dribble tube dribbling?
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IF you have no pump and the tanks are below the engine, what do you think the servo inlet pressure will be?
 
pathetic GA engine tech.. "new engine with 400 hrs" and it already has a critical issue

PS - glad you made it but I think you used up one of your "freebie mulligan" lives flying it there on the electric pump. At least in the Cirrus there's a warning that the electric pump "may not be sufficient" to supply fuel to the engine.. it's mostly just a vapor lock preventative and primer
 
Salty said:
IF you have no pump and the tanks are below the engine, what do you think the servo inlet pressure will be?
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I get that you like to argue for argument's sake but I was talking to the OP.
 
Stewartb said:
I get that you like to argue for argument's sake but I was talking to the OP.
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The OP is flying a low wing. If that electric fuel pump had failed his engine would have stopped. His aircraft was not designed to run continuously with only the electric fuel pump. There is no argument in this post whatsoever.
 
Tantalum said:
pathetic GA engine tech.. "new engine with 400 hrs" and it already has a critical issue

PS - glad you made it but I think you used up one of your "freebie mulligan" lives flying it there on the electric pump. At least in the Cirrus there's a warning that the electric pump "may not be sufficient" to supply fuel to the engine.. it's mostly just a vapor lock preventative and primer
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I won't comment on the whole taking off with a known malfunction side of the ledger, but from a technical standpoint I'm afraid you're talking Apples and Contis -er- I mean pumpkins, :D. The Lyco FI electric pump setups in the NA variants are rated for continuous duty and neither starve nor flood the engine in open throttle operation. It's functionally....hope you're sitting down for this.... a second main pump. :eek:;)

Conti FI setups otoh are football bats. They do have a better mechanism for hot starts, since they're designed to flood the manifold and thus have return lines and flooding-rated boost pumps that allow for easier purging of vapors prior to attempting said hot start. I'll still take the harder to hot-start setup in the Lyco since I'm a W2 prole who can't afford a parachute, and otherwise fly Contis only in even numbers anyways.

Talking about the even number or chute philosophy on contis, former squadronmate had one of his RAM 520s blow a rod right off the top of the case in cruise flight last week (Cessna 340 RAM) with family on board. 600 hour engine (1600 TBO, which I didn't know was that low actually), #2 con rod, womp womp. He's pretty ****ed about the longevity question. I'm of course not one bit surprised, but I won't kick the man when he's down. Math worked though, all safe back on the ground. No insurance claim on this one though *ouch*.
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Sorry for the drift, now back to stoning the OP for daring flying on a Lyco-installed electric pump. :p
 
I had a rod break like that on a Continental IO-360. Metal throughout the engine, prop, and prop governor. Very expensive.
 
Stewartb said:
The spec is for servo inlet pressure. It doesn't specify where the tanks are.

I have a bad habit of forgetting to turn on my aux pump for takeoffs and landings. I need to add a pump status light to remind me.

MacFly, was your engine driven pump's dribble tube dribbling?
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No, no dribbling.
 
hindsight2020 said:
Talking about the even number or chute philosophy on contis, former squadronmate had one of his RAM 520s blow a rod right off the top of the case in cruise flight last week (Cessna 340 RAM) with family on board. 600 hour engine (1600 TBO, which I didn't know was that low actually), #2 con rod, womp womp. He's pretty ****ed about the longevity question. I'm of course not one bit surprised, but I won't kick the man when he's down. Math worked though, all safe back on the ground. No insurance claim on this one though *ouch*.
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Damn.. see and this is the part of GA that really bothers me. We have exorbitant costs and yet the reliability and dependability is dubious at best. You can buy some serious flying equipment for as little as $100K.. but, are you ready for that $50K rebuild in 2-5 years?

It's madness.

I wonder if it's just "big engines" in general though that tend to have issues, and ones that are ridden harder (like turbo's that spend their whole like between 75% and 100% power, as opposed to the NAs that cruise closer to 65% or less). I wonder how many hundreds (thousands) of club beater O320 and O360 engines there are well beyond TBO that still keep chugging along.. compared to the bigger engines that seem to have continual issues. Not long ago a Comanche was (perfectly) placed down on the highway here after he lost the engine.. there was an Aerostar that sat at Ramona for a little while with a destroyed cylinder on the left hand engine, and many Cirrus people you'll talk to have a hard time making it to TBO.. some needing work as early as 800 hours

Lightweight and simplicity is important, but people also (literally) depend their lives on this stuff. If it's poor engine operation that causes issues (running hot, running it too hard, etc.) then we have some work to do there in training pilots and standardizing practices that goes further than internet forums and "well Mike Busch said this, but I think he's an idiot, Lycos have no problem running well over 400!" or whatever

Either way, sorry for your friend. Glad he and family are fine.. but damn, that engine quit hard!
 
hindsight2020 said:
I won't comment on the whole taking off with a known malfunction side of the ledger, but from a technical standpoint I'm afraid you're talking Apples and Contis -er- I mean pumpkins, :D. The Lyco FI electric pump setups in the NA variants are rated for continuous duty and neither starve nor flood the engine in open throttle operation. It's functionally....hope you're sitting down for this.... a second main pump. :eek:;)

Conti FI setups otoh are football bats. They do have a better mechanism for hot starts, since they're designed to flood the manifold and thus have return lines and flooding-rated boost pumps that allow for easier purging of vapors prior to attempting said hot start. I'll still take the harder to hot-start setup in the Lyco since I'm a W2 prole who can't afford a parachute, and otherwise fly Contis only in even numbers anyways.

Talking about the even number or chute philosophy on contis, former squadronmate had one of his RAM 520s blow a rod right off the top of the case in cruise flight last week (Cessna 340 RAM) with family on board. 600 hour engine (1600 TBO, which I didn't know was that low actually), #2 con rod, womp womp. He's pretty ****ed about the longevity question. I'm of course not one bit surprised, but I won't kick the man when he's down. Math worked though, all safe back on the ground. No insurance claim on this one though *ouch*.
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Sorry for the drift, now back to stoning the OP for daring flying on a Lyco-installed electric pump. :p
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I'm surprised to see a shiny crank journal and not the jagged end of a broken rod. Do you know the rest of the story of how the rod failed? Any holes in the cowl?
 
Salty said:
Wouldn’t be talking about that in public if I hadn’t gotten a ferry permit to do it (which I doubt one would be issued)

The reply to your argument that it was only 12 miles would be, it’s only 12 miles, so not difficult to move the part and mechanic rather than the aircraft.
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nothing illegal about it, no ferry permit needed, nor would one be given. its experimental. is up to him even to put two pumps in it to begin with.
 
unsafervguy said:
nothing illegal about it, no ferry permit needed, nor would one be given. its experimental. is up to him even to put two pumps in it to begin with.
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That’s an interesting point. I’m not sure it’s completely accurate, but I’m also not saying it isn’t, I just don’t know.

Regardless, I still think it’s a really, really bad idea to fly with a malfunctioning mechanical fuel pump, even if legal, just my opinion.
 
Salty said:
Regardless, I still think it’s a really, really bad idea to fly with a malfunctioning mechanical fuel pump, even if legal, just my opinion.
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Then you should never, never do that.
 
Salty said:
That’s an interesting point. I’m not sure it’s completely accurate, but I’m also not saying it isn’t, I just don’t know.

Regardless, I still think it’s a really, really bad idea to fly with a malfunctioning mechanical fuel pump, even if legal, just my opinion.
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i don't disagree with you about doing it, but here is the legal side.
from FAA order 8130.2H:
(a) A special flight permit may be issued for an aircraft that may not currently meet applicable airworthiness requirements but is capable of safe flight, for the following purposes:

there are no applicable airworthiness requirement for an EAB aircraft. You never use the word airworthy to describe an EAB because of this. An EAB condition inspection is signed off with the phrase ""I certify that this aircraft has been inspected on (insert date) in accordance with the scope and detail of appendix D to part 43, and was found to be in a condition for safe operation."

which is exactly what a special flight permit allows with a type certificated aircraft.

so if the pilot determines the aircraft is a condition for safe operation it meets the requirements for flight the FAA spells out for an EAB, however, if there is incident i am willing to bet that FAR91.13 is going to be part of the discussion.
 
Salty said:
They aren't flying low wing aircraft either, I'd wager.
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doesnt matter, if the fuel pumps on a injected cessna quit the engine will also. you can't get enough head pressure to run a FI engine with just gravity feed.
 
Stewartb said:
I'm surprised to see a shiny crank journal and not the jagged end of a broken rod. Do you know the rest of the story of how the rod failed? Any holes in the cowl?
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I don't know the rest of the story on the rod, he said RAM's on the case doing oil analysis. Not sure what angle there is, since 600 seems late for a warranty claim. At any rate, as soon as he gives an update I'll add to the story.

Tantalum said:
It's madness.
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Oh I hear ya. The level of Stockholm syndrome when it comes to rationalizing eating insane costs for 1940s tractor engines in this hobby is unreal to me. At least the EAB guys have the clone engine market (and the legal avenue to jump in and out of it), which helps alleviate things a little bit.

It's one of the reasons I'm unwilling to dig deeper on the capex front; engine costs vis a vis warranty and reliability track record in this market is an all-hat-no-cattle affair to me. As an admitted beggar in the economic rung (resale participant), I don't object to the crappy reliability per se... I just don't feel like paying year 2020 listed cost premiums for what I know is a quality control basket case in a grossly non-recoursed cotton industry. I'll keep dumpster diving for IRAN and serviceable potato, and roll the dice like we essentially are doing unwittingly anyways.
 
Dick the Mechanic got the fuel pump today and installed it. Engine now running with the fuel pressure at the top of the green he tells me, so problem apparently solved. My buddy and I will take his courtesy car back (4 hour drive:() and retrieve the plane tomorrow.
 
Hopefully you're happy with the plane in spite of this hiccup.
 
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