Faulty starter solenoid or key switch ?

[Andrew Hamilton]

Recently developed an intermitent problem starting 0-360 Superior, sometimes having to hold key on for several seconds before starter will engage. Is this a faulty starter solenoid or could the problem be in the key switch.
I see in the Vans store they now offer protection diodes for the starter solenoid which weren't available when I finished my RV-7A several years ago.
Any thoughts are much appreciated.

 

[Lycosaurus]

Keyswitch contacts

Recently developed an intermitent problem starting 0-360 Superior, sometimes having to hold key on for several seconds before starter will engage. Is this a faulty starter solenoid or could the problem be in the key switch.
I see in the Vans store they now offer protection diodes for the starter solenoid which weren't available when I finished my RV-7A several years ago.
Any thoughts are much appreciated.

Andrew,

I take it you do not have a protection diode on your starter key switch wire (placed near the solenoid). This diode prevents arcing at the keyswitch from back-emf. The arcing slowly destroys the contact integrity of the keyswitch.

The solenoid or other part downstream may be flaky, however my money is on the keyswitch contact.

To test, remove the keyswitch wire from the solenoid, and place a voltmeter (or a 12v light bulb) connected from the keyswitch wire to grond (if I remember correctly, the keyswitch wire powers the solenoid with 12V)

Now activate the keyswitch. If you see intermittent power being applied then the keyswitch is faulty and you will need to replace it.

You can also just pull out the keyswitch and disconnect the wire there and perform the same check... or pull it out all together and check it on a bench with a ohm-meter.

You'll want to install protection diodes at all your solenoids inputs.

Good luck.

 

[Andrew Hamilton]

Alfio,
Many thanks for your help.
Before I built a plane I knew very little about the electrical systems.
I learnt alot during the building and still have alot to learn.

Thankyou.
Kind regards,
Andrew