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Old 06-19-2017, 08:37 PM
tim2542 tim2542 is offline
Join Date: Aug 2009
Location: Redding,Ca
Posts: 594

Good comments but I would add put a voltmeter on the battery after it has set for at least several hours. If it not 12.8, it's not fully charged and yes that is .2 volts higher than a regular lead acid. If it is down, you need an approved charger to get it right, or a very long flight or two. Regular charger won't go into the saturation mode long enough to top it off. And it's a good chance this is your problem.
These batteries can lose capacity if kept too long at less than full charge, but you can recover them by drawing them off into a headlight or similar, down to 10 volts or so, recharge and repeat until the capacity comes up. Full instructions for that on Odyssey's website.
Tim Andres
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Old 06-20-2017, 04:29 AM
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N941WR N941WR is offline
Join Date: Jan 2005
Location: SC
Posts: 11,289

Originally Posted by ssokol View Post
...I know I've got good spark - one e-mag and one standard, both of which check out fine during run-up. ...


E or P-mag? The company is Emag Ignitions and early on they sold both an E-mag and a P-mag but now only sell the P-mag. The difference is the P-mag has an internal generator and the E-mag does not.

If you have a P-mag and it is prior to version 40 of the firmware, get it in for the upgrade and inspection. One of the things version 40 does is during starting is to fire the plugs at 4 degrees after TDC. Either way, try starting it with the traditional mag grounded (off) so it does not fire before the E/P-mag and then turn on (in-ground) the mag. That may also help you.
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
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Old 06-20-2017, 06:07 AM
vic syracuse vic syracuse is offline
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Join Date: May 2005
Location: Locust Grove, GA
Posts: 2,268

You might want to check that you don't have a parasitic drain on the battery and you are really beginning with a half-drained battery.

Vic Syracuse

Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
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Old 06-20-2017, 06:30 AM
Robert Anglin Robert Anglin is offline
Join Date: Mar 2008
Location: houston, texas
Posts: 791
Default Me too.

You have some very good suggestions above and I too would tell you that the 680 PC will carry the load if in good shape. Two other things that do come to mind here. The older big factory starters don't turn an engine very well and turn them slower than needed for good starts. And if the battery is good and has full load carrying capacity one needs to get as much of that pressure to the starter as one can so the starter can use it. We have seen so many RV's with #4 starter cable on them. Some times this works OK with a new generation starter, but if you want to get all the juice you can from the battery to the starter and not have much of a voltage drop or pressure drop if you like that term. Make your ground and feed cables for the starter circuit from #2 and clean good cable ends and luges so that you can transmit as much of that power to your starter motor as you can. And really old starters will start to drag tell you through twice the amperage on them with a jump supply.
Just a couple of pennies to put in the pot. Yours, R.E.A. III #80888
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Old 06-20-2017, 06:59 AM
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olyolson olyolson is offline
Join Date: Dec 2009
Location: St Louis, MO
Posts: 692
Default Starting


Had some start issues when I first bought my -4. The airplane has an IO-360 with a C/S prop which the builder decided needed the battery in the baggage compartment for weight & balance. Changed the starter wire to a #2 as described above (long way from the battery to the starter). Also changed the 149 LS lightweight starter to a 149 NL high torque starter and swapped out the PC 680 with an Earth X battery. I did all these one at a time and at each step the engine started faster & faster. To compound the problem, somewhere in this process the starter solenoid gave up further complicating the issue.

All those changes spun the prop incredibly fast but my hot start technique was lacking to say the least until someone clued me in (this was first injected engine). Ditto what my cousin Mark says above for a good hot start technique:

"Hot start procedure is simple: Throttle full, cycle the mixture once (full rich and back to ICO), crank."

Oh and did I say NO BOOST PUMP? Each engine behaves differently but Mark's technique describes the most common hot start method.

Oly Olson
AEIO-360, Hartzell C/S
RV grin every flight
"Sure is nice to have smart friends"
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Last edited by olyolson : 06-20-2017 at 09:26 AM.
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Old 06-20-2017, 07:03 AM
WAM120RV WAM120RV is offline
Join Date: Dec 2006
Location: Coventry. England
Posts: 595
Default Dispair!

Threads like this often make me wonder what you guys are thinking, then I slap myself and remember that the mechanical knowledge of most pilots is Zero!

From what you have said the problem is not the battery. The problem is poor hot starting which causes you to run the battery almost flat. So cure the hot starting problem and your battery will be fine.

Now you say 1 email make sure it is V40 as has been previously suggested. That upgrade prevents a host of othe potential problems

Does the mag have an impulse on it. If so with an email and an impulse you can be fairly sure of a good spark

You mentioned at the outset vapour lock, what have you done to address this and eliminate it as a cause. That is where I would start after ensuring the mesh is V40.

Hope this helps! BTW my 0-320 on a PC 680 with two PMags starts hot or cold second blade. Ok it is carbed but all fuel lines are fire sleeved and insulated from heat sink.

Steve Arnold

In completion stage of Loehle P5151
Built and now Flying G.BVLR Vans RV4
Rebuilt G.BDBD Tailwind
Rebuilt G BVTN Kitfox
Built G CDCD RV9A with WAM120
Riveted wings on Glastar G.LEZZ Now (G. SKUA)
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Old 06-20-2017, 07:12 AM
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titanhank titanhank is offline
Join Date: Aug 2007
Location: Friendswood, Tx
Posts: 184

My -6 with o-320 was doing the same thing as yours. I replaced the pc680 and it still would not start half the time and when it did, it would barely make it over the compression stroke. I tracked mine down to a burnt starter solenoid. The stock starter solenoids are bad to pit the copper disk inside every time the engine starts. I broke mine open and the face of the contactor looked like the surface of the moon. This does not make a good contact and severely restricts your cranking amps. I would replace the solenoid. They are cheap and easy to change. I also ran a ground cable directly to the starter. This makes it start right up.
Dual pmags
Catto 3-blade gen 3
Smoke system
Glass panel

Last edited by titanhank : 06-20-2017 at 07:16 AM.
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Old 06-20-2017, 07:17 AM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 7,606

Originally Posted by ssokol View Post
Long time lurker, first time (as an RV owner) poster.
Steve, all successful hot start methods base on a simple concept. The engine will fire when supplied a mixture that is within a fairly narrow range. So, the goal is to sweep the mixture through that range during the start process, either by beginning in a lean condition and moving toward rich, or beginning in a rich condition and moving toward lean. Either way, when you hit the sweet spot, it will light.

Sweep lean to rich (from Nigel):

Throttle open ~1/2 inch
Mixture Idle Cut Off
No priming, boost pump Off
Starter engage
Mixture slowly forward ('slowly' is at a rate that would take you from ICO to rich in about 5 seconds) until it starts, which is usually about mid range.
Throttle as required to set idle RPM
Mixture lean
Boost pump as required to keep it from stumbling if the fuel pressure fluctuates.

Sweep rich to lean (from Randy):

Throttle full open
Mixture full closed
As soon as it starts:
Throttle back to hi idle quickly
Mixture about 3/4 open (This is different on all planes)
If you have trouble keeping the idle, run the boost pump after it starts.

As a personal preference, I recommend learning the "lean to rich" method, as it does not begin with the throttle at WOT. The "rich to lean" method becomes a backup plan if it doesn't fire sweeping from lean, as it was left in a rich condition.
Dan Horton
Barrett IO-390
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Old 06-20-2017, 09:17 AM
Chkaharyer99 Chkaharyer99 is offline
Join Date: Oct 2011
Location: Pilot Hill, CA
Posts: 796

When I first bought my RV8 with IO360 I would run my battery down on hot starts because I didn't understand what my engine needed to start when my fuel system was compromised by boiling fuel. It's really disappointing when that happens.

It was a post like DanH and others that made the difference. Bottom line is you need the right air/fuel mixture, sparks at the right time and a starter system with a good enough battery to turn the crank rapidly enough.

My procedure is lean to rich like described. Almost always works. If that fails (occasionally it does) I go rich to lean. The fuel pump goes on right after start as mine spits as sputters until it does.

I recently upgraded from an Odessey PC680 battery and skytec Light Weight starter to a SJ16 battry (220 CCA) and B&C starter. I'm very impressed with the B&C.
The B&C engages first try, everytime and spins the engine faster with less amperage draw then the permanent magnet starter I was using.
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Old 06-20-2017, 10:04 AM
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erich weaver erich weaver is offline
Join Date: Aug 2006
Location: santa barbara, CA
Posts: 1,499

Im not criticizing the above hot start techniques; whatever works, right? I do find it odd however that folks are recommending against using the boost pump just prior to starting. I use mine, per the procedure recommended by by AFP. The logic seems sound to me: Circulate cool fuel from the tank through the system with the purge value open to get rid of the vapor while avoiding flooding the engine.

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