Fly with a bad fuel pump?

[chrixxer]

35 minutes ago, teejayevans said:

FWIW, my A3B6 is ~20, 25 with boost pump on.

My F usually sits around 23-25 psi with the boost pump off, FWIW. Green arc is 14-30 psi. (Damn, I have a lot of pictures of my panels in flight...)

My E (also an -A1A) sat around 20 psi in flight, boost pump off (same green arc).

Edited July 23, 2018 by chrixxer

[BigD]

I would ask for ferry permit, that way if they reject it, you can take that to airport manager.
If they approve, find a ferry pilot.
You got 7 lives left by my count, so if you do it yourself I would plot the course over roads, early Sunday morning to avoid traffic, and circle the airport to get altitude before departing.

This is sage advice.


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[Browncbr1]

did you do the Dixie cup test using boost pump?   

You can also do the Dixie cup test with mechanical pump if you pull the plugs and crank it over.   

I would not fly it in its current state.   On my 67F, to get the fuel pump off, we had to remove the mag, and move some hoses, but also had to loosen the motor mount in order to get the arm out.   (The firewall was too close to the pump to get the arm out).   

[Hank]

Wonder if they out in the wrong mechanical fuel pump? 2psi is a normal cruise reading in my C, don't recall idle power pressure.

[HRM]

FWIW, my last flight for about an hour...

[chrixxer]

Wonder if they out in the wrong mechanical fuel pump? 2psi is a normal cruise reading in my C, don't recall idle power pressure.

2 psi? In cruise?!

The mechanical fuel pump in 3RM appears to be original to the airframe.


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[chrixxer]

Wonder if they out in the wrong mechanical fuel pump? 2psi is a normal cruise reading in my C, don't recall idle power pressure.

2 psi? In cruise?!

The mechanical fuel pump in 3RM appears to be original to the airframe.


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[jaylw314]

33 minutes ago, chrixxer said:

2 psi? In cruise?!

The mechanical fuel pump in 3RM appears to be original to the airframe.


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My eyebrows lifted looking at the IO-360 TCDS.  The maximum fuel pressure is listed as 35 psi, and the minimum psi is listed as -2 psi?????

[EricJ]

43 minutes ago, chrixxer said:

2 psi? In cruise?!
 

Carburetors don't need much pressure, just flow, but 2 psi sounds a little low even for a carb.

[ragedracer1977]

1 hour ago, EricJ said:

Carburetors don't need much pressure, just flow, but 2 psi sounds a little low even for a carb.

I usually sit around 5-6 psi in my carb C

[Hank]

7 hours ago, chrixxer said:

2 psi? In cruise?!

The mechanical fuel pump in 3RM appears to be original to the airframe.


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Sure, all the time. Red line on my fuel pressure gage is 6 psi, the wide green line is 2.5-3.5 psi.

Wasn't your fuel pump swapped out during troubleshooting? If not, it's probably the right one, but something is bad wrong. 

[HRM]

12 hours ago, jaylw314 said:

My eyebrows lifted looking at the IO-360 TCDS.  The maximum fuel pressure is listed as 35 psi, and the minimum psi is listed as -2 psi?????

interesting...could be a typo, but I doubt it. Probably the suction pressure that anything beyond starts to collapse tubing or something.

[jaylw314]

29 minutes ago, HRM said:

interesting...could be a typo, but I doubt it. Probably the suction pressure that anything beyond starts to collapse tubing or something.

I know, I was shocked.   I double-checked to make sure I was not looking at the TCDS for the carbureted O-360, that has limits of 0.5-18 psi.

[RobertGary1]

On 7/22/2018 at 5:20 PM, Yetti said:

The mechanic has desires to move it.  Unless he has desire to fly it....    I would not do it.   Yes it is more time to do the fuel pump.  Should take about 3 hours to change it out, it can be done with the mags on.  Some people say the mags need to come out, but if you are good at working blind it can be done.   The plane is already in a post maintenance state.   Hopefully they will let you do some fast taxi on their long runway.   The question is between 0 feet and 3000 feet. 

Do you take the engine off the mounts and rock it forward?

-Robert

[chrixxer]

59 minutes ago, RobertGary1 said:

Do you take the engine off the mounts and rock it forward?

-Robert

I did not. I don't know, but I doubt if, the mechanic did so. Lack of tools / etc. (he's working on it on the ramp, next to an active Hawkeye flight line, with whatever tools he can hand carry from a parking lot about a quarter mile away...) 

(Realized belatedly this was in response to something else. I'm fried...)

Edited July 24, 2018 by chrixxer

[Yetti]

1 hour ago, RobertGary1 said:

Do you take the engine off the mounts and rock it forward?

-Robert

Nope.   I did sacrifice a 5/16" allen wrench to make it the best length.   About 2"   I may have used some 1/4 inch drive sockets.   A couple wrenches for the fuel line and the allen wrench, sealant and safety wire and about 4 hours.   With lots of working by feel.  Spent alot of time getting the prop in the right place to get the lever in the right place with the gasket in the right place and start the cap screws.

[Guest]

1 hour ago, RobertGary1 said:

Do you take the engine off the mounts and rock it forward?

-Robert

That sounds like a needlessly complex way of changing the pump.

Clarence

[Yetti]

1 minute ago, M20Doc said:

That sounds like a needlessly complex way of changing the pump.

Clarence

That sounds like a needlessly way of creating lots of other might as well projects.   Like might as well change the motor mounts

[RobertGary1]

1 hour ago, M20Doc said:

That sounds like a needlessly complex way of changing the pump.

Clarence

I seem to recall more than a decade ago when I had a MSC change my governor that's what they said they did. Fortunately last time I did the gov it was with the engine off. Unfortunately it was because the engine came apart is spewed metal fragments through the governor.

-Robert

[chrixxer]

Update from mechanic:

"With boost pump on, engine makes full power. Without boost pump on, engine is limited to approximately 2100 rpm.

"The last fellow who offered his advice did not realize that the initial issue was the engine not making full power and quitting while in normal flight. This made an inflight restart necessary. The inflight failure was either caused by the ingestion of the ram air gasket into the throttle body of the fuel servo or the low fuel pressure either causing fuel percolation, based upon vapor pressure, or basic fuel starvation.

"If I recall our conversation correctly you said you could get the engine to make limited power by pulling the mixture back. That would be consistent with the fuel servo throttle body being restricted by the ram air gasket enough to make the fuel mixture too rich to support combustion due to the limited air flow.

"Let me know if I’m missing something. But I think we have enough facts now to draw some conclusions. The fuel lines look good with no fuel leakage observed from the entire fuel system.

"The review above is just so I can use you as a sanity check."



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[MIm20c]

I hope you get back into the air soon. I’m curious where the io360 fuel pressure probe is. On certain installs of the io550 it’s taken after the mixture control reduces the pressure. Around 11 psi wot lop is fairly common.  I wonder if that’s why the normal operating range is so wide. 

[Guest]

The fuel pressure pick up on Lycoming powered Mooney’s is taken off the finger screen housing on the servo.

Clarence

[MB65E]

Chris, what has been changed so far. 

Just the servo? 

Make sure the pump is the correct one and supports FI aircraft and not Carbed aircraft. 

-Matt

[Browncbr1]

Chris,

After a mechanical fuel pump is installed, you need to crank the engine with the plugs out to verify the new mechanical pump is pumping.   Sometimes, the finger misses the pin that moves up and down inside the case.    It is possible to install a mechanical pump that ends up not pumping because the pin is kinked to the side and missing the top of the finger... 

that 2psi might just be coming from gravity??   

Craig

 

Edited July 25, 2018 by Browncbr1

[RobertGary1]

Since I had Lycoming send me a new IO-360 my fuel pressure on the mechanical pump is always at the top of the green. Turning on the boost doesn't change anything when the engine is running.

 

-Robert