454 running rough and smoky

[atl_jim]

I have a 1996 Crownline 215CCR with a 454. Since bringing it out of storage for the year I have been having issues with it running rough and smokier than normal. At idle, it's struggling to keep running at times. When it's been idling for a period of time and I give it gas, it bogs down and studders a little bit before it starts running decent again. It doesn't have the normal low rumble it normally has but a little bit higher popping at idle. On two occasions this year I have stopped on the lake and had to fight to get it running again. Both times felt a lot like a flooded motor as I waited a little bit and was able to get it running again. This is a fuel injected motor so I'm not even sure it's possible to flood it, nor am I sure what would even cause this when I had no problem in the past.

My first thought this year was that the old gas that had been treated with Sta-bil in the fall was the culprit. So I ran the old gas down. Currently it's at about a 1/3 old gas, 2/3 new gas mix. This has done little to aleviate the problem as it seems to be worse than it was earlier this season.

Another thought I had was that the motor was not running on all 8 cyclinders. I have checked to make sure all the plug wires are secured on the plugs however that's all I've done at this point.

A friend suggested I might have water in the gas tank that may be causing this. My next step is to drop some dry gas and fuel injector cleaner in the tank, however I'm not optimistic this is the solution. Another suggestion was to replace the wires and distributor cap.

Any ideas what could be the cause of this? It really has a feel like it's running rich due to the fact that it gets that flooded feel and it is smoking a bit more.

Any suggestions or help would be very appreciated as I'm anxious to enjoy the boating season!

Thanks,
Jim

 

[Don S]

Re: 454 running rough and smoky

Sounds like the automatic choke isn't opening when it warms up. Pull the flame arrestor off and see if it works.
When was the last time it was tuned up?

 

[Bondo]

Re: 454 running rough and smoky

When was the last time it was tuned up?

Ayuh,... If a Tune-Up, or the Choke don't fix it,... Rebuild the Carb...

 

[atl_jim]

Re: 454 running rough and smoky

It's had a partial tune-up recently however nothing with the automatic choke was addressed. I will take the flame arrester off and see what's going on there. When I first start it cold, I have to give it a little gas to keep it running typically (lately), But wouldn't the automatic choke only affected it on a cold engine? Even when the engine is warm, it's not idling properly and it's studdering on acceleration.

Bond-O - since it's fuel injected, it doesn't have a carb right?

 

[Don S]

Re: 454 running rough and smoky

since it's fuel injected, it doesn't have a carb right?

Don't ya think that might have been some good information to know in the original post, none of us are mind readers.

 

[atl_jim]

Re: 454 running rough and smoky

Don S - I'm just asking for some help here man. I tried to include as much information as possible in the original post. And the fact that it's a fuel injected motor was in the original post.

Thanks.

 

[Bondo]

Re: 454 running rough and smoky

Ayuh,... I missed that too.... I guess you don't have a Carb, nor a Choke...

Being an EFI,.. You're kinda limited to Electronic diagnosing it...

 

[Rip Tide]

Re: 454 running rough and smoky

Hi Jim, I'm new here and definately new to boating. However I've had quite a bit of experience with GM engines. Past experience has shown me that whenever a driveability problem arises, do the simple stuff first. All new gas, full tune-up (plugs, wires, cap, rotor). Then if the problem persists, get into more complicated diagnosis. Also always gap your new plugs, they don't come set for your engine. Hope this helps, and you get your problem resolved.

Ryan