Fuel Boost Pump Voltage Regulator

[Dean Showalter]

Fuel boost pump is not working in "low" position.  It's an M20K, S/N 25-1187.  We're doing an annual inspection and need to fix the issue.  After troubleshooting, it appears the boost pump regulator P/N 880047-503 (model VR536) is bad.  We can't find a new one.  Anybody know of a shop that can repair this one?  Or where we can buy a new or serviceable one?  It's an Electrodelta part.  Thanks!

[Fly Boomer]

3 hours ago, Dean Showalter said:

Or where we can buy a new or serviceable one? 

Welcome!  How about LASAR?

https://lasar.com/fuel-system-1/fuel-boost-pump-regulator-880047-503

 

[Dean Showalter]

Thanks... I saw that as well, but when you try to add the part to the cart, it says "out of stock."  We've not been able to locate one yet.

[Fly Boomer]

4 minutes ago, Dean Showalter said:

Thanks... I saw that as well, but when you try to add the part to the cart, it says "out of stock."  We've not been able to locate one yet.

Give LASAR a call.  Sometimes their web site isn't accurate.

[Will.iam]

On 12/7/2024 at 1:06 PM, Dean Showalter said:

Fuel boost pump is not working in "low" position.  It's an M20K, S/N 25-1187.  We're doing an annual inspection and need to fix the issue.  After troubleshooting, it appears the boost pump regulator P/N 880047-503 (model VR536) is bad.  We can't find a new one.  Anybody know of a shop that can repair this one?  Or where we can buy a new or serviceable one?  It's an Electrodelta part.  Thanks!

Rats, I’m in the same situation except my annual is not til February. Was really hoping it would be an easy fix. Hope you find a place that has the part. I will be needing one soon as well. 

[Bolter]

Would a pump overhaul shop like Aeromotors have something like this, since it is related? 

[Fly Boomer]

4 hours ago, Dean Showalter said:

Thanks... I saw that as well, but when you try to add the part to the cart, it says "out of stock."  We've not been able to locate one yet.

I would also try Don Maxwell in Longview TX (world's most renowned Mooney shop).  He used to rebuild them.

I assume you have bench tested it to eliminate switches, breaker, wiring, etc.?

[Dean Showalter]

I really appreciate all the help on this.

I called and spoke with Oli at Aeromotors, and had a great conversation with him... but they don't work on these boost pump regulators.

And then I just got off the phone with Don Maxwell and he was very helpful as well.

My next step is I have a local friend / previous avionics technician / A&P who used to have a television repair business... he's going to take a look at it and see if he can repair it... if not, I can send it to Don Maxwell for repair.

At least now, we have uncovered some very good options!

I'll keep you guys posted.

[Dean Showalter]

Hey guys, I thought give an update in hopes it might help some others out there, especially Will.iam who said "Rats, I’m in the same situation except my annual is not til February."

We ended up sending the boost pump regulator to Don Maxwell's shop in Texas.  He has a contractor who repairs these units.  It worked out very well.  They turned it around in timely fashion and it worked great.  I adjusted it for the proper fuel pressure on "LOW" setting and the owner is happy to have it working again.

And for what it's worth, they returned the bad transistor to us that was replaced.  If it was simple, I could have done that myself.  But after taking the box apart, it looked pretty complex in there, just to change the transistor... all this to say, if I ever encounter this issue again and the part is not available, Don Maxwell Aviation will be the first thought on my mind.

Thanks Don, and keep up the good work on Mooneys!

Dean Showalter

P.S.  On this same airplane, I encountered a challenging issue with sealing up small exhaust leaks at the cylinder flanges / gaskets.  I talked about it in episode 249 of the Airplane Owner Maintenance podcast, in case anybody cares to listen to it... I'm certainly open to more thoughts and ideas from others who may have had the same issue.

[Yetti]

This is for a similar fuel regulator on the R model.    Pretty obvious what failed.  Parts are in the last post. 

   "

Hey @Dominik_B -- there are two components there, the rectifier (2 legs) and the bipolar transistor (3 legs).  I'll link to the ones I used below.  And just in case someone is reading this years in the future and the reseller has removed their product pages, the rectifier is MUR1540G and the transistor is 2N6668 PBFREE.  

 

https://www.mouser.com/ProductDetail/onsemi/mur1540g/?qs=Gev%2bmEvV0iZq6LchZ03NqA%3D%3D&countrycode=US&currencycode=USD

 

https://www.mouser.com/ProductDetail/Central-Semiconductor/2N6668-PBFREE?qs=l7cgNqFNU1ijRYXR1DLWNQ%3D%3D&countrycode=US&currencycode=USD

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Edited February 10 by Yetti