Today's engine puzzler #2

[rv6n6r]

I was inspired by David Harris's recent puzzler -- and who doesn't love Click and Clack? Here's my engine puzzler. Probably an easy one but I'm posting because it stumped me for a while, and perhaps some other engine-challenged folks like me can get some benefit. At the risk of getting beat up like David did, I'm not going to post the answer right away. But it will be later today or tomorrow, or as soon as someone gets it. If you're frustrated by that you can subscribe to this thread and you'll get the follow-ups in your inbox.

So here's the setup: at around 1400 hours the engine began having a hard starting issue. Mostly it would start right up but maybe 1 out of 10 times it would just crank and crank. I could get it started with some starter fluid (I know, not safe, but it did the trick).

This is an RV-6 with Lycoming O-360 A1A, cabureted, P-mag right side with aircraft ignition harness, traditional magneto left side, iridium lifetime plugs all around. I had the magneto serviced, adjusted the carb, checked the fuel screens & verified no water in the fuel, cleaned & gapped the plugs. Checked all ignition wires with no problems found. No change.

Then I listened to an EAA webinar by Vic Syracuse. Bingo!

The clues are there, if you know the answer write it on a set of James Aircraft RV-6 high speed fiberglass pressure recovery wheel pants and send it to me PO box [etc.] OR post it here :-)

[Hitt7A]

Malfunctioning primer

[rv6n6r]

Originally Posted by Hitt7A

Malfunctioning primer

No primer installed. Should have said.

[rv8ch]

Bad ignition key switch?

[rv6n6r]

Bad ignition key switch?

Don't have that either, just a starter button and two mag switches (actually a grounding mag switch and a P-mag switch). All working good.

Again, the clues are in my original description, not in any component I didn't mention.

[Skid]

Do the Irdium plugs have screw on ends for the plug wires to attach to? I would believe that could cause that issue. Although you stated a convention mag on one side so that couldn’t be an issue for those plugs.

[Taltruda]

He mentions that a spray of starting fluid will make it start, so I?m thinking the electrical and ignition systems aren?t the problem. I?ll guess that the carb bowl is draining out somehow..

[BobTurner]

Originally Posted by Taltruda

He mentions that a spray of starting fluid will make it start, so I?m thinking the electrical and ignition systems aren?t the problem. I?ll guess that the carb bowl is draining out somehow..

I agree, fuel problem. I?d guess a stuck needle valve (once engine starts with starter fluid the vibration frees the valve).

[AaronG]

Starts with starter fluid, so likely not electrical.

Starts with extra fuel added, so likely too lean.

My guess is in intake leak. Old intake gaskets or hoses?

Aaron

[Boyd Birchler]

Failed induction tube gaskets or hoses.