Hi all,
I just purchased an 09 1800sr3 4.3L having only 57 hours on it. The boat had the original oil filter and gas/water separator and who knows if the fluid we're ever changed. Anyway I replaced the filters, changed the fluids and the thing runs great-ish.
The boat has the occasional hiccup where I give it throttle from idle and the engine rpm falls to nearly stalling and I bring it to neutral and it recovers. Then it's like it never happened and I can accelerate and drive like nothing happened. This happens occasionally and doesn't seem to be influenced if I idle longer or not. The worst part is as I bring the boat to the launch and trailer it always has these dying moments as I shift from fwd to rev and try to pulse my way onto the trailer.
I thought it was bad gas, unfortunately it's not. Does anyone have any experience with this before I start into throttle cables, tps sensor or IAC valves?
Thanks for any help!
Is this a carburetor or MPI engine? If carburetor then no IAC. What drive, Alpha 1? If so is the engine loosing power when shifting out of gear into neutral? If so it’s most likely an issue with the lower shift cable causing the shift interrupt switch to stay closed too long.
Hey, thanks for the reply. It's an MPI engine with an alpha out drive. The issue is actually going into gear... Same underlying problem? That's the switch that momentarily kills the engine to allow shifting?
Hey, thanks for the reply. It's an MPI engine with an alpha out drive. The issue is actually going into gear... Same underlying problem? That's the switch that momentarily kills the engine to allow shifting?
Yes the interrupt switch temporary kills the ignition to relieve load on the Alphas dog clutch to make it easier to shift and reduce wear. By design this should only happen when shifting out of gear but if either misadjusted or cable drag to high issues arise. However if this were the problem I would expect it to kill the engine. Sounds like you’re saying yours still runs but with a rough idle.
Yes that's correct. Intermittently out of neutral the engine stumbles and almost stalls. In these instances I've kept it in gear for a few seconds before returning to neutral where it recovers almost instantly. Then miraculously it runs beautifully only seconds after that when I shift out of neutral again.
You may be able to adjust your lower shift cable and finish the season, but I would recommend replacing the cable in the off season. Once this problem starts it keeps coming back until the cable is replaced. You also replace the shift bellows with the cable, which is great idea on a new-to-you boat.
Ok, so my understanding is that the shift cable has too much drag and slack and is engaging the interrupt erroneously and for too long of a duration. I read the sticky at iboat about this system and it makes sense I guess. I wouldn't have thought the cable would be worn with only 60ish hours on the engine but I guess it's how many shifts that matters. I'll also look at the routing.
Thanks for the help!
Throttle issue... of some sort
Linear Mode
