Ovation Low Boost Pump Failure

[carusoam]

Over the last three months, my Low Boost Pump has been misbehaving...

(1) turn the switch on, it runs for a while and stops intermittently...

(2) the intermittent stopping got to be longer and longer...

(3) earlier this week I hit the switch and nothing happened...

(4) the High Boost works as usual...

(5) the high Boost cannot replicate the LB's abilities. LB can run continuously while the engine warms up.

(6) the engine dies at least once after start without the LB continuously running.

(7) I take the plane to see the mechanic. He pushes the LB button, it works fine...

(8) I get a brief lesson on the adjustable pressure setting related to the low boost switch and what I might expect to do if the 1.5 AMU pressure regulator needs to be swapped out...

(9) I look forward to going back tomorrow to push the switch again.

(10) total run time on this pump is about an hour total. 15 seconds per fight...

(11) there is no fuel pressure gauge in this modern O.

My question...

Any of you fine Mooney pilots have difficulty with your LB switch not turning the fuel pump on?

Maybe it just needs more exercise,

-a-

[carqwik]

If it works some of the times and not other times, then it's (probably) not the pump but likely the switch that's the problem. 

 

Just went through a quick bout of my electric trim working intermittently from the yoke switch.  It worked fine with the autopilot running the show but hit or miss from the yoke...sprayed quick dry electrical contact cleaner on the yoke switch (after pulling it out somewhat from the yoke itself) and it now works all the time.  No mechanic needed.  Took about five minutes.

[Jeff_S]

I've got nothing on the fuel pump switch, but I had a similar experience with another electronics part that (wonderfully) fixed itself. The range/joystick knob on the MFD of my G1000 wasn't working after I bought the plane last summer. I could push and get the joystick and move the cursor around, but when twisting to control the range view nothing happened. I consulted Garmin and several avionics guys, and the consensus was I would have to pull the MFD and send it to Garmin for a flat $1000 repair (plus the cost of pulling/replacing the unit of course).  Given that the automatic range adjustment feature worked fine, I just decided to let it ride.

 

Lo and behold, in April I was futzing with the knob on a long flight to KC and it magically started working again. I had been both pushing and twisting at the same time for some reason that eludes me at the moment, but I theorize that since the plane had been living in Florida prior to my ownership (and not flown often) that corrosion had built up on the contacts, and after some drier Atlanta air and more usage that corrosion finally cleaned off. That was the first time in my life that an airplane problem fixed itself. I'm happy to have saved the AMUs, but not counting on too many more such instances!

[lmtinley]

On 6/12/2015 at 11:06 PM, carusoam said:

Over the last three months, my Low Boost Pump has been misbehaving...

 

(1) turn the switch on, it runs for a while and stops intermittently...

 

(2) the intermittent stopping got to be longer and longer...

 

(3) earlier this week I hit the switch and nothing happened...

 

(4) the High Boost works as usual...

 

(5) the high Boost cannot replicate the LB's abilities. LB can run continuously while the engine warms up.

 

(6) the engine dies at least once after start without the LB continuously running.

 

(7) I take the plane to see the mechanic. He pushes the LB button, it works fine...

 

(8) I get a brief lesson on the adjustable pressure setting related to the low boost switch and what I might expect to do if the 1.5 AMU pressure regulator needs to be swapped out...

 

(9) I look forward to going back tomorrow to push the switch again.

 

(10) total run time on this pump is about an hour total. 15 seconds per fight...

 

(11) there is no fuel pressure gauge in this modern O.

 

My question...

 

Any of you fine Mooney pilots have difficulty with your LB switch not turning the fuel pump on?

 

Maybe it just needs more exercise,

 

-a-

Hi, I have this exact problem now in my Ovation. What ended up being the problem? I've had to start the motor priming with high boost on the last three flights. 

[carusoam]

Just now, lmtinley said:

Hi, I have this exact problem now in my Ovation. What ended up being the problem? I've had to start the motor priming with high boost on the last three flights. 

there is a controller board for the fuel pump...

Hi boost, nothing gets in the way...

Lo boost, the controller board adjusts the output...

The controller board starts failing after 20years...

 

Let’s see if @M20Doc is familiar with where this device is mounted, and how to get it fixed...

It may be a Continental part and not a Mooney part...

PP thoughts only, not a mechanic...

Best regards,

-a-

[GeeBee]

Had a friend with an Eagle with similar symptoms. Loaned him my controller, problem went away. He tried getting a new controller, no joy. Bought one from a salvage yard. New Mooney may have them now.

 

[Mark89114]

I have an ovation and the low side quit working.  It is somewhere, relatively easy to access on the right side of the panel.  maxwell repaired the board for relatively low cost, he has a guy who knows which part to replace.  I don’t have the invoice as it was stolen, long story,

[Guest]

This should help you find it.

Clarence

[N177MC]

I successfully repaired the controller on n Eagle.  It's usually the power transistor that burns up.

[G-SLOT]

In a similar vein, what fuel flow do you typically see when priming with the low boost pump (mixture and throttle full forward)?

[carusoam]

5 hours ago, G-SLOT said:

In a similar vein, what fuel flow do you typically see when priming with the low boost pump (mixture and throttle full forward)?

I have the FT101 display...

And use seconds to count off fuel flowing to the engine...   1, one thousand, 2, one thousand....

I start counting after the FF becomes active on the FT101...

Unfortunately, i don’t remember the details of what the FF actually reads...

With the hi pump on, it’s about five seconds, then off for start...  whatever number it is displaying is in transition and not terribly meaningful On this display...

Expect that it should be going towards 25+gph.... if full fuel is unrestricted heading towards the engine... (?)

The Hi boost needs to replace the engine’s mechanical fuel pump that delivers the max fuel flow that you see during the Take Off run...

PP guessing only... not a mechanic...

Best regards,

-a-

[lmtinley]

Thanks everyone for the replies. I'm dropping her off with Maxwell with weekend to get the controller fixed. Will update with the results.