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-   Traditional Aircraft Engines (https://vansairforce.net/community/forumdisplay.php?f=21)
-   -   The starter engages (delays) approx 5 secs after the key is turned to "start", why? (https://vansairforce.net/community/showthread.php?t=116599)

JanRV6UK 02-23-2016 05:23 AM
Quote:
Originally Posted by ao.frog (Post 1056049)
Hi guys.

This is an update to the tread I started a while back:

Two things has happened since then:

1) I have replaced the starter relay but the delay is still there.

2) The delay has gradually became longer: now it's 13-15 secs.

Therefore, I have decided it's time to get to the bottom of this once and for all. Today, I did some more checking and here's the results:

Immediately when the starter relay "clicks", there's power on the out side of the starter relay and the starter turns the engine.

When I manually put 12V onto the starter wire, the starter immediately turns the engine.

Therefore, it seems to me that the starter and the starter relay is OK.

I measured the volts on the little terminal on the starter relay which receives power from the ignition switch through a small wire.
I guess that's the terminal who makes the starter relay engage when you turn the key.
(I have the A-510-2 ignition switch)

There I discovered something strange: when I turned the key to "start", the volt on the little terminal showed 9,2V and then slowly started to increase. After approx 15 secs, the volt read 10,5 and didn't go further. (the starter key was held in "Start" position all the time)

Then I made a new wire, and connected it from the terminal of the ignition switch and to the little terminal of the starter relay.
The result was the same: approx 9,2V when the key was turned to "start" and held there. The volt climbed slowly to 10.5 and stopped.

Finally, I took a wire and connected it directly from + on battery to the little terminal on the starter relay, and now the volt read 12,0 right away and stayed there.

Based on these new findings, I'm thinking the fault is within the A-510 ignition switch. It seems to me that 9,2V on the little terminal shows that somewhere from the ignition switch and to the little terminal, there's some resistance who "steals" the volt.
The wire from the ignition switch and the little terminal is short, so I doubt the fault is there.
That leaves me with a faulty 510 ignition switch.

Before ordering a new one, I'm wondering if any of you have some other ideas?

Thanks.

regards Alf Olav
Hei Alf,

If you want to "prove" it is not the wired from the switch to the contactor ... run your good 12V test feed directly on the wire connected to the ACS starter switch ... or even simpler .. just jump the switch input ... to the switch output ... the engine should start to crank immediately ... That will show that the terminals in the switch have a high resistance .. giving you the voltage drop ... When you replace the switch .... open it up and take some photos of the internals ...

One other thing .. do you have a fly back diode fitted on your starter contact coil ? I assume you do ... but if you do not .. that will cause the starter switch contact points to deteriorate quickly .... Just a thought ...

Jan

Edwardoc 02-23-2016 11:22 AM
I to am having SkyTec Starter engagement delays. I also use the same key starter switch from ACS. I returned the starter to them and while they said it was fine I had them do a rebuild to update it. Upon reinstall it still delays. I can hear the relay on the starter "click" but no rotation at first. My Battery voltage shows a drop from about 12.3 v to 11.2-11.5 v. If I hold the key ofter the starter engages. Occasionally it will not engage even after holding for about 15 seconds. If I hold it and someone carefully moves the prop it usually engages and will engage after that sometimes. SkyTec suggested I run a wire directly from the starter terminal to the cockpit and when it does not engage put a volt meter on it and read the volts. They think I'm getting low voltage at the starter. I am also going to read some readings at the key and at the A/C starter relay. :)

jakej 02-23-2016 06:46 PM
A simple thing to check -One area that can cause problems is if you have not removed the paint from the engine where you attached the earth lead - found that sort of issue many years ago :-)

vic syracuse 02-24-2016 06:34 AM
I just recently had the solenoid that is attatched to the starter fail, and it showed the same symptoms---- a drop in voltage but no engagement of the starter.

Vic


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