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Bogey59
06-08-2009, 01:15 PM
'98 Outback 350 Indmar Carb, after running WOT engine stalls when throttle back to idle speed.

This seems to be only after running at WOT, no problems at crusing speeds or at ski speeds of 34-36mph

Plugs are new, checking fuel after sitting up over the winter. May try some seafoam in fuel.

She runs great other wise and am able to recrank in neutral when I throttle to about 2000 rpm.

Any quick check ideas?

PS these are short duration WOT's - I was checking response as I like to barefoot at 44MPH and check runs were at 1 min intervals and stalled after each check run.

Any help or ideas would be greatly appreciated.

ToddXLV
06-08-2009, 05:05 PM
'98 Outback 350 Indmar Carb, after running WOT engine stalls when throttle back to idle speed.

This seems to be only after running at WOT, no problems at crusing speeds or at ski speeds of 34-36mph

Plugs are new, checking fuel after sitting up over the winter. May try some seafoam in fuel.

She runs great other wise and am able to recrank in neutral when I throttle to about 2000 rpm.

Any quick check ideas?

PS these are short duration WOT's - I was checking response as I like to barefoot at 44MPH and check runs were at 1 min intervals and stalled after each check run.

Any help or ideas would be greatly appreciated.

I had the same problem with my old 1989 Seaswirl Spyder with a Quadrajet 4 barrel carb on a Chevy 350. I believe it's from running hot for an extended period. You may want to clean your carb too. Take off the air cleaner and open up the butterflys in the carb and see if you have any build up. But If I ran my boat at WOT for a while then stopped, it could take me another 5 minutes to start the boat. I would go thru the flooded procedures to get it going again. So I would put the throttle all the way down for a about 10 seconds in neutral then try cranking again until it turned over.

When is the last time you cleaned your carb?

mmandley
06-08-2009, 05:15 PM
Im thinking your running too Rich, starving the engine for air at WOT, then when you come off WOT the engine is full of fuel and is suffocating for air.

The reason it takes to long to start is the fuel has to clear out of the engine to lean its self back again.

If your WOT and come out of it to say 1/2 throttle does it stall still?

gcnettl
06-08-2009, 05:58 PM
I like the running rich idea.

kaneboats
06-08-2009, 05:59 PM
I was thinking he might have an air obstruction too.

Bogey59
06-09-2009, 11:53 AM
Thanks for the feed back! There seems to be no issue when throttle back to cruise from WOT, just when throttle back to idle.
Operating Temp is 175- so I dont think its heat causing the problem.

I'll be checking for vaccum leaks this weekend- and report back. Other than vaccum how should I check for running to rich?

Razzman
06-09-2009, 12:28 PM
You could have an internal issue with the carb. While many auto carb theories apply, others don't. One nuance of a marine carb is that the float bowl overflow returns right to throat of the carb, take off your flame arrestor and look at the top and you see a fairly large diameter tube that curves over into the carb throat. That's your overflow which prevents fuel from spilling anywhere but the carb.

That's one reason for not using a auto carb unless you like big bangs! :p So when debris clogs the float or age attacks it such as a leaking float seam, fuel will dump into the carb. Backing off the throttle from full to idle causes havoc in the carb as it has to adjust asap. Older carbs are usually suspect with gunk and debris in the float bowl. That's where i'd start, also check and replace the fuel filters. If it still does it i'd rebuild or replace the carb.

So unless you've messed with the carb that's about the only way for it to experience a too rich condition other than clogged jets that i can think of. Btw if you have a vacumm leak your idle will be erratic or not at all, how's yours? How does it start cold? Hot?