SN 196 excalibur sputtering on take-off: Help!

[jdk99]

2003 SN 196 excalibur 330.

 

Drysuit run yesterday.

 

On holeshot/initial acceleration, sputters misses for 1 to 2 seconds then accelerates to speed without issue. No issues idling, or at speed. Black smoke from exhaust when sputters. Becomes progressively worse during the course of a given outing but only on initial acceleration. After 3 or 4 sets, will actually stall out on acceleration and "check engine" light comes on. Will restart after several cranks and light goes off.

 

Thoughts greatly appreciated.

 

 

[DW]

Black smoke is a rich condition. You might have a leaking injector assuming fuel injection. Another hint if a fair leak will be a rising oil level and thinning of the oil. If carbed, there are several possibilities, perhaps the accelerator pump(s) are leaking or debris in the system is causing another issue such as a high float level.

[paul]

how old is your gas? Our boat does something similar with old gas. Put some fresh 91 octane in and see how that goes.

[nzcabbage]

Take off the distributor cap and you will most likley find a crusty growth on the contacts inside. Used to happen to our last club boat of the same year. Give them a clean and all will be good. If the corrosion is too bad, replace the cap with a new one.

 

[gregy]

My buddy's 08 MC Prostar 197 was doing that. It had around 350 hrs. Two dealers worked it and couldn't figure it out. Ended up being a worn drive gear on the distributor. Replaced the distributor and all was well.

[jdk99]

Thanks a ton for the info guys. Appreciated. Already tried the high octane fuel @paul. Will check the distributor next.

[Spuddy]

We had something similar with our '97 196. Would do the same as yours on take off but would also start to cut out over 30 mph. It was the anti-sphion valve which was restricting the flow of fuel.

[jdk99]

OK. Checked the distributor. Looks brand new and in fact it's marked as having been replaced in May. Back to the drawing board. Perhaps leaking injector as per @DW. At the end of my wrenching ability. Time to take it in unless anyone else has an idea.

[alex38]

i once saw a similar issue, problem was DEFECTIVE cap. Prob not the same thing but just to cover all bases

[A_B]

My thoughts were with @DW. When you see black smoke, usually means too much fuel and running rich. In the old days, I tore carbs apart on cars and boats, and rebuilt them. Nowadays, I don't know much about EFI, so would go to Planet Nautique or Correct Craft Fan websites and post a question out there, or take it to a dealer. There are some pretty sharp mechanics on those websites, and if you look around, something like it may have already been posted.

 

I could only offer that you could pull each spark plug to see if one or a couple are blacker than the others, after just idling and seeing the black smoke. If you run up the rpms, you would probably burn the excess fuel off and not be able to see as much. That might help isolate what injector is bad, if it is.

 

If you haven't, might not be a bad idea to run some Seafoam cleaner through a tank of gas, or a good fuel injector cleaner.

[paul]

a longer shot but you might want to check your fuel pressure. Our fuel pump went and it would sputter and the check engine light would come on.

[gregy]

Could be fuel pump or fuel regulator or even fuel filter. There should be a valve port on the fuel line that is threaded. You can rent gauges at an autoparts store. From my experiences those engines are 40 or 60 psi depending on year and have to stay pretty close to that within about 5 psi.

 

There is also fuel injector cleaning kits were you hook to the pressure port and disable the pump so its running straight cleaning. It's a good idea to do this every few years anyway.

[Drago]

Black smoke is unburnt fuel, have the spark plug wires been replaced?

[DanE]

Check fuel pressure regulator for broken diaphragm, if it's broken Engine Will be fed fuel through vacuum hose.

[LeonL]

My analysis is an electrical/electronics problem. Here's why: you report no problems at idle, if an injector problem it would be rich at idle, sputter/miss at acceleration usually indicates a lean condition as opposed to rich, so I don't think it's a fuel delivery problem, as someone else mentioned you're just not burning the fuel that is delivered. My .02.

[Roger]

When was the last time you changed the plugs?

[jdk99]

Thx guys. Plugs replaced last may. Pulled the plugs. 2 of the 8 had cracks in the porcelain but otherwise looked ok. Could cracked plugs do it? Will replace but don't want to pull her to the lake to test if a plug change isnt likely the issue.

[McGruder]

Yes, a cracked plug could cause those symptoms.

[Drago]

Absolutely a cracked plug could do that

[gregy]

Plugs shouldn't crack, might try a different brand. Make sure when you install them that you don't put any pressure that could crack the porcelain.

[McGruder]

If you drop a plug during the install process, pitch it and get a new one. Dropping will crack them, and often where you do not see the crack. Its not worth the headache. Handle with care, and if any doubt, install new.

[A_B]

So no black on the plugs vs nice light brown?

[DanE]

Cracked porclain could be your issue for sure, just want to Point out that a leaking diaphragm in the press regulator can cause very intermittent symptomes

[LeonL]

Cracks? Are you sure you used the correct heat range plugs when last installed?

[DW]

Cracked porcelain allows the spark to jump to ground (cylinder head) rather than the plug gap. You can test by running in the dark and simply looking to see the spark jump. The key will be to understand how they cracked. Usually install or removal is the cause particularly working around the exhaust manifolds. Make sure the plug socket does not put a side load on the tip of the plug due to rubbing on the exhaust manifold, if yes, get a different socket (thinner).

[jdk99]

Thanks guys. @ AB, plugs looked good otherwise, just a light brown without heavy black. Plugs were placed by someone else last may. No issue removing with standard plug socket (PCM 330 has pretty easy access). I'll replace em and give it a go. We shall see.