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O390 Weak Starter

F

Frankster13

Active Member
I have a beautiful, flying airplane. It’s a 14A with the O390.

I’m having issues with the starter from day one. It was build to the plan’s specifications. The starter does not seem to have the power to crank the motor over swiftly and stalls. It seems to do better with a warm engine however.

The starter and prop freeze/stall during start. I have to continue to engage starter when it stops and then will slowly kick over and continue cranking. I have a new motor, new starter and new Odyssey battery that I keep on trickle charge. It seems the starter is not sufficient to start the O390.

Any recommendations or suggestions? Are others having this issue? Is there a starter upgrade available?
 
Normal issue

My guess is you have a Skytek lightweight starter? You can change the starter to a NL (and risk snorkel interference) or go to an Earth X battery ETX900 flavor of choice. Either will solve the issue. I’m assuming you have a IO390 not O390…
 
Not a "Normal" issue...but...

...a well understood one...

Check your connections and voltages along the various points from the battery, through the Master Relay (Littelfuse 24115), the Starter Relay (Littelfuse 24012), the wire from the "I" terminal on the Starter Relay to the Starter Solenoid, the BFW-2ga wire from the Starter Relay to the Starter Motor. The Ground Wire from the motor to the motor mount. An aside, I recommend that you double up on or abandon the Van's "recommended" installation on the engine ground.

Ground the motor directly to the firewall/Batt (-). Use the lug on the motor case next to the lower left motor mount (5/16" hole - clean off the paint).

If all that fails, there is a known issue with a certain lot of clone starter solenoids that seems to be heat affected.

Replace the "beer can" solenoid that sits next to the starter motor. The replacement part is a BWD (Borg Warner) S5613 -- available from most autoparts suppliers as the starter solenoid for the 2005 Ford Crown Victoria (4.6L V8).
 
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dmattmul said:
My guess is you have a Skytek lightweight starter? You can change the starter to a NL (and risk snorkel interference) or go to an Earth X battery ETX900 flavor of choice. Either will solve the issue. I’m assuming you have a IO390 not O390…
Click to expand...

Came here to say this. Agree.
 
I have a 14A (IO 390) with the lightweight LS starter (Odyssey 680 batt) with 750 hours and haven't had this problem. Definitely not super fast cranking, but will usually provide a few 20-second start attempts (40 deg F) before winding down. I've had a few dead battery cases, once when I ran it down working on the panel, and twice before I figured out how to do hot starts. Consequently I always carry a jump starter (like this:
https://www.amazon.com/DBPOWER-1800...4&psc=1&mcid=270b1e5fe9e4359fa6ac7bfc9829f7d7
which has always solved the problem)
My FWF is all stock Van's, including the engine ground.

What I'm saying is that your problem is most likely some excess loss in the starter circuit or components. Checking the ground is definitely a good start. Maybe get some jumper cables and make a temporary engine ground to see if it helps. Or maybe get a jump starter like the one above and see if connecting it helps (could be a defective battery). If you have an EFIS with voltage readout see what happens to the voltage while cranking. There are lots of electrical system gurus on this forum who could jump in and help :)
 
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check grounds

It's been mentioned already, but I'll back it up with experience.

I had this problem on my -7. Just recently I was looking around the engine while doing an oil change. I grabbed the ground wire at the engine itself and could move it. I tightened that bolt and nut and haven't had the problem since.

Easy fix and it's free!
 
bjdecker said:
The Ground Wire from the motor to the motor mount.

Ground the motor directly to the firewall/Batt (-). Use the lug on the motor case next to the lower left motor mount (5/16" hole - clean off the paint.
Click to expand...

I have an NL-EC starter, just installed a brand new 2GA cable from batteries to starter, and don't have any starting issues, but I'm still going to check this as preventive maintenance since my cowling is off and all the floorboards are removed, thanks.


Freemasm said:
Go here/do this before replacing any componentry.

https://skytec.aero/aircraft-starter-performance-issues/
Click to expand...

Very detailed ! I'm going to copy it for future troubleshooting, thanks !
 
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