Electrical problem, any ideas?

[MHemperly]

Well here is my problem

Last night couple friends and I jump in the airplane for an 80nm x-country to visit another buddy. So two of us get into the airplane to taxi down to the other end of the airport to pick up one more that's going on the trip (he is a cfi and teaches at my home field). When I turn the master switch on all seems normal. When I hit the fuel pump to prime the engine the pump hesitates for a second and then speeds up. When I turn it over I get a pop from the exhaust ( I think I did prime it a little too much, reason for the pop). So we taxi'd down to pick up our cfi buddy I shut it down and we get everything situated in the airplane. It took about 15 minutes before we were back in the airplane to get going I hit the master switch and the gyros start spinning again everything seems normal I hit the fuel pump and nothing. I gave it a minute and tried again and nothing. I called my mechanic and he seemed to think it was the fuel pump. After getting off the phone I try again and everything works perfect. Airplane starts just fine alternator shows a charge everything is running perfect. So we decide to go to the run up area and do a thorough run up again everything is prefect so we are on our way. Airplane ran great as always battery is pulling zero amps avionics, light all electrical is perfect. We land at French valley lock up the airplane and head to our buddy's house.

Now it's the next morning we get back to the airport and I do a preflight all looks good. We load up and when I go to hit the master. Nothing. I hear the battery solenoid kick on but nothing else hit the fuel pump and nothing. Turn everything off let it sit a sec try again and nothing. So I toggled the master switch about 5-7 times and finally we get power. Gyros come alive my 496 powers up fuel pump kicks so I get it going start up, again everything is running perfect. Alternator shows a charge the whole 9. Go down to the run up area do a thorough run up and it all checks out. We get in the air and it's running great and it did the whole way home. Battery wasn't pulling any amps all is well. So we land back at Van Nuys I park and put the airplane to bed. And it was just bugging me so much I had to go look things over. I checked the battery all looked good, clean terminals water levels looked normal. All connections looked good. I looked under the panel at the wiring by the master and fuel pump all looks secure and nothing is loose. So I try to start the airplane and again nothing when I hit the master so I toggle it like I did 5-10 times and finally hear the gyros start to turn but they sound weak and slow so I toggled it agiain and they speed up and sound normal so I hit the fuel pump and it doesn't do anything it actually shuts everything down when I hit the fuel pump. 496 shuts off and gyros stop spinning. So I turn everything off and let it sit a minute and try again. Same thing, hit the master gyros sound slow and then I toggle the master and finally get them to speed up and this time I hit the fuel pump and it primes as normal but this time I go to hit the starter and when I do it, shuts everything down when. So now I can't even get it started. I called my mechanic and explained the situation and he seems to think it may be a bad master switch or even the maybe the battery solenoid or even possibly a bad battery. He was just guessing as he doesn't live close and couldn't come look at it. He told me to put a volt meter on the battery and check it so I will do that in the next couple days. But as far as exactly what the issue is I'm lost. Everything looks normal when the power finally came on line it had no problem starting the engine so I don't think it's the battery I just think it's a connection problem.

So I figured I'd share this with you guys and see if you have any ideas or have experienced the same thing. Any suggestions or help would be greatly appreciated. I am going to have my mechanic fix it. I just want to see if maybe I can narrow the problem with your help. Thanks for reading and sorry it was so long.

Regards and happy safe flying

Mike

[orionflt]

Check your master solenoid, could have burnt contacts causing a bad connection

[carusoam]

I vote on the solenoids giving you a hard time...

Your description is solid enough to take to your maintenance guy....

Good luck,

-a-

Check the voltage coming out after each time you toggle the switch...

[MHemperly]

Check your master solenoid, could have burnt contacts causing a bad connection

Thanks orionflt. My mechanic mentioned that on the phone. Just out of curiosity if it turns out that this is the issue what would cause this? Just an old solenoid?

[carusoam]

They get old and dirty after forty years...

They don't cost much either. They are easy to find.

Best regards,

-a-

[MHemperly]

They get old and dirty after forty years...

They don't cost much either. They are easy to find.

Best regards,

-a-

Makes sense. Where is the solenoid located at in the airplane?

[N201MKTurbo]

On the back of the battery box

[MHemperly]

Thanks for the help guys. I'll keep you posted on the outcome.

[Seth]

My former 1967 Mooney F had the starter solonoid go bad.  It was a 43 year old part at the time.  I also had my aux fuel pump go bad in that airplane about 6 months later.  Replaced both wtih new, as I figured the first ones lasted for 43 years, the next ones had some good life in them.  I ended up selling the aircraft about a year later.  Cost difference for an overhauled pump would have been only a few hundred less than a brand new one, and it was one of the last brand new ones available as parts were just beginning to be in lower supply at that time, so I opted for a new pump.  Still sold the Core to the old one to a refurb shop.

 

My current 1983 Mooney Missile (Modded J) had issues with the master switch last year causing varying voltage.  Turns out it was just the contacts at the master swtich.  The wires were nice and tight, but I detached the wires, cleaned the contacts, reattached, and the problem was no more.

 

Good luck!  It may just be contacts on the Master that need to be cleaned, but it sounds like it may be more than that.  When my fuel pump was at the end of it's life, the resistance, or grounding issue, or something internally caused a horrible screeching sound on the intercom when it was in use as well as an electrical burning smell. 

 

The solonoid just wouldn't engage when it was time to restart the engine after a stop during a training flight (had to get some charts at a different airport - hadn't converted to the ipad yet), causing the engine starter to simply not engage.  All the gyros started spinning, master switch worked fine, and bam, starter simply would do nothigng. 

 

It happens that the instructor was a mechanic, so we decowled the airplane at the remote strip while the sun was setting.  My starter solonoid was located on the backside of the instruemnt panel on the firewall side of the instrument panel.  We got to it using a screwdriver and hammer and just tapped it with no fuel in the engine until we got it to engage.  We then recowled the airplane, got the plane started, and flew it right to the MSC to have the solonid replaced (he dropped me off at my field on the way - only time I ever got out of an airplane with the engine on - we didn't want to turn it off as we might not get it started).

 

Good luck finding the gremlin.

 

-Seth

[MHemperly]

Is the 12v solenoid a continuous operation or intermittent?

Seth- I checked the connections on the master switch and everything looked good. Considering the panel was done last year they should look good. I don't think it's the starter solenoid because after I got back from my trip when I tried to start it I would toggle the switch and finally get enough power to be able to hit the fuel pump without the gyros turning off. Once it was primed I went to start it and once I turn the key to start I heard a click on each attempted from the back by the battery.

[Mooneymite]

Can't really speculate until we know the condition of the battery (under load).

[MHemperly]

so the voltage of the battery is still 12.7V on the volt meter. and when i check the hot side of the solenoid it reads the same. I had a buddy sit inside while i held the volt meter on the cold side and it read zero volt as it should with the master switch off and while holding the meter on there he turned on the master and all i got was 4volts out of the other side. 

[carusoam]

Damn we're good!

I would guess that more than 4V is required to operate a 12V motor.

The device is continuous. You turn it on and it stays on until you turn it off and it goes off. The master switch hold voltage to it to hold it closed.

How much for the new part?

Best regards,

-a-

[MHemperly]

Damn we're good!

How much for the new part?

Best regards,

-a-

haha yes sir you are! the part was $57 from aircraft spruce. picked it up on the way home from work today.

 

thanks! 

[carusoam]

The power of MooneySpace at work!

-a-

[MHemperly]

The power of MooneySpace at work!

-a-

No doubt! I'll let you know how everything goes after the part is installed! 

 

Thanks again guys!

[Seth]

Congratulations!  Glad the troubleshooting worked. 

 

-Seth

[MHemperly]

Well its a done deal! Solenoid is replaced and everything is working great! the fuel pump even sounds stronger when i prime it! must of had a bad connection for a while! 

 

Again THANKS for all your help guys! 

 

Mike