Bogging Down in Gear, then won’t restart until sitting

[Chaser33]

Our A4 has been running great the past few years, and started right away on launch 1-week ago. Several trips out on the lake, maybe 3-4hrs of running, no issue.

Last night after a 1hr sail, we restated the engine, started easy. When putting into forward, engine bogged-down like it was under a good load, but was pushing the boat along well. Then sputtered and stopped. It wouldn’t restart. Tried a small shot of ether, not even a puff or two.

After sailing in for 10-15 min and checking various things, it restarted but instantly bogged and sputtered to quit when put into gear. Wouldn’t restart.

Sailed into the marina, coasted into the slip... waited 15-20min, started right up and idled smooth.

I will check plugs and even compression. My thought was transmission? But what has me scratching my head is the failing to restart. I couldn’t check for spark when it happened (I had to sail with no engine)... but with no puff on ether, I assume there was no spark.

The OPSS had given us some issues years ago, but that only effects citting-off the fuel pump.?. I would expect with a squirt of starting fluid to get it to kick-over even with OPSS tripped, or would that kill the spark too?

Could high blow-by trip the OPSS, and explain both the bogging-Down and the failure to restart?

Any thoughts, appreciated.

[ndutton]

Was there any engine or driveline maintenance done over the off season?

[Tkenopic]

I would definitely check the prop shaft for a wrap of some kind (fishing line or other flotsam/jetsam) since it is idling ok. Might save you time chasing down other ghosts...

[JOHN COOKSON]

33
Do you have an electronic ignition module or points inside your distributor?
Your symptoms are a classic case of a heat damaged coil that is on it's way to total failure.
After the next shutdown immediately pull the big wire out of the center of the coil hold it near the engine while cranking to check for spark. A blue-white spark is good. This test will tell if the shutdowns are ignition related or not.

TRUE GRIT

[Chaser33]

TG - thanks for the reply. The coil makes sense, and easy to try! The not getting spark for a period of time was getting me. I’ll try and report back!

Thanks as well for the other replies! No maintenance over the winter. As for the prop & shaft, I haven’t dove-in to check, but pretty confident it isn’t fouled because the bogging down got progressively more, a wrap-up would have happened fast. Thanks for the ideas though, and as I work through I’ll make sure to cross it off the list if the solution doesn’t come quick!