Electrical Gremlin in starting

[superchamp]

My Stinson has been giving me an intermittent electrical problem. To start, I turn on the master, then hit the starter button, and after 3 blades turn on the mags. The problem I have occassionally, as soon as I hit the starter button, all electrical goes dead (you can hear the electric gyro shut off). If I shut the master off, and turn it back on, the electrical powers up again. Then I hit the starter button, sometimes it cranks, and sometimes it shuts everything down again before it cranks. No circut breakers pop. I am suspecting something loose/or shorting out in the starter button itself, but whenever I want to test it, I can't get it to repeat the problem. I'm on floats, and fortunately it hasn't yet done this when I have shoved loose from a dock in a good wind, but the time is coming I'm afraid. Any ideas? I have check all the cables on the battery, starter, etc for tightness. Russ

 

[UP-M5]

sounds like the master contactor is getting bad and losing its internal connection. turning the master off and back on gets you a good connection again.

 

[Clyde and Susan]

It could actually be an internal bad connection between cells in the battery, I've seen that in the past. Otherwise it can still be one of the connections you've checked. The way to troubleshoot that is to connect a voltmeter on each side of each connection and then have someone activate the starter. A good connection will show near zero volts but the bad one will show from 5 to 12 volts when the starter is drawing current. ...Clyde Davis

 

[jrussl]

Check the battery cable where it is connected to the airframe. Pull the connection apart and clean any corrosion off. As Clyde pointed out above, you can also check this connection with a voltmeter.

Jeff

 

[superchamp]

Thanks guys. Just got back from a 4 day Canadian fishing trip, and fortunately did not have a single no start. I will check all you mentioned. Still hoping to have it fail here at home so I can track it down with my tester. It only does it where there is no tools or time to look for the gremlin.

 

[behindpropellers]

Make sure there is a ground strap from the engine mount to engine also.

Tim

 

[nanook]

gremlin

it sounds like a large voltage drop across your starter relay. You have to have 12 volts to hold the master relay closed. Your voltage drop is knocking your master relay off line... If you have dirty(burnt) contacts in your relay the resistance causes a voltage drop...find the voltage drop....

 

[BSEC]

It could actually be an internal bad connection between cells in the battery, I've seen that in the past.

Been there done that...

I had the same problem in a 185 and replaced everything one by one except the battery. I didn't replace the battery because it was less than a year old. Because the problem only came up a few times a year it took 2 years to try everything. Last spring I broke down and replaced the battery. I haven't had a problem since and wish I had tried the battery first.