Could very well be ignition just due to the fact he says the plugs are ball balck. He was talking about steam in the original post so that sounded like water getting in a cylinder. Plugs would be clean though if they were seeing any water. I have seen where the hall effect sensor in the dist will have this type of problem when hot. You might check that.

Took some pics of the plugs tonight, along with a paper towl after I wiped one of them off. Seems like most of the oily/carbon residue is around the threads, but no oil was on the part of the plug outside of the block, so it didn't come from above. All the plugs were similar. Also, took about a pint of oil out of the oil pan, it was not milk shaky.



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I know this is an old thread....well, my old thread, but wanted to add to it. I sent it to a local shop and they said they couldn't get it to do what I described. Went for a ride....was perfect. Next time out, the issue was back. It's usually after a hard run....then shut down for say 30 minutes. Start up and she idles a tad rough, and stumbles when given gas. However, last time out I just nailed the throttle and she came out of it and started runnning fine. ANy ideas?

change the fuel filter/water separator,you may have got some fuel with water in it.

Id look into a issue with the carb. Float sticking, needle and seat malfunctioning, well plugs leaking. The old quadrajet carbs were no exceptions to these issues.

Pull the engine oil dipstick. Does the engine oil smell like gasoline? Did you notice a strong smell of fumes from the exhaust when experiencing the issue?

fixx
 

if it is a carb model check the choke pull off to make sure the choke is not snapping shut at idle..also the pick up in the distributor are common to go out and will cause a misfire..also check the alternator voltage at the back of the alternator,,if its below 12.8 its junk,,should be 13.2 or higher..

I honestly couldn't tell you, this took place late last year before I put her into winter hibernation. To clarify, it was stumbling trying to get on plane, then I hammered the throttle...and kept it there. After about 2-3 seconds the motor came alive and the stumble was gone. I'm pretty sure the water/fuel separator was replaced as part of winterization, so if that's the problem it should be fixed. I'd been considering getting the carb rebuilt in the offseason because I'm pretty sure it's never been done (boat came with a ton of maintenance history). Anyone inparticular to send this carb to for rebuild?

Hall effect sensor, and they show problems hot and clear up cold often.

Are these old q-jet carbs? If so, the float bowls may be leaking.

A number of years back, I worked in a tune-up shop. Whenever a carb needed a rebuild, we would keep the car overnight to verify the cold start was OK the next morn. The q-jet guy showed me where the casting plugs were located in the float bowl. Over time, the plugs in the casting holes would loosen allowing fuel to leak from the float bowl into the manifold. He would smear some JB weld over the casting hole plugs to stop the leak, let dry overnight and re-assembe the carb the next morn.

The fuel leaking into the manifold would flood the eng unless it sat long enough for the gas in the manifold to evaporate. This situation would also cause longer than normal cranking times the next morning due to the float bowls having to re-fill. Just a thought..

I believe the carb is original to the boat which is a '91.