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engine sluggish on hard acceleration

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Lake555 View Drop Down
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    Posted: August-02-2019 at 12:06am
We have a 91 SN. Last summer we experienced difficulty getting a skier out of the water. On acceleration, the engine would cough and sputter and not have the power to pull up a skier. This would occur after using the boat for about an hour. The first hour the engine would run fine and did not have any problems on acceleration. We took it into the marine and they first replaced the fuel filter. We tested it the next weekend and the same thing happened, for the first hour everything was fine, but then it started to sputter and cough again on acceleration. We took it back to the marina and they then replaced the spark plugs, cleaned the seats and flame arrestor and found a loose fuel line. We thought this finally fixed the problem because the last month of the summer, boat seemed to run fine. But most of the time we did not run for more than 45 minutes at a time.   Then this summer the problem came back again. It seems to only happen after we run the boat for a good hour or so, then it will start to cough and sputter on acceleration and not have the power to get a skier up. After the boat sets overnight, it will run well again and have power, but it seems if you run it over a hour and it gets hot, the engine will sputter on acceleration. The marina did install a Protec retro kit about 7 years ago. What would you suggest we do next to fix this problem? Thanks for your help.
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KENO View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-02-2019 at 11:30am
The quote below is from you in 2011. Sounds a lot like what you're saying now   

it seems like it was an expensive ignition problem back then.

I'd be looking at the ignition system again, maybe starting with a new coil.

You can test it with an ohmmeter and it can test good every time............till it runs for a while then gives symptoms like you describe.

The coil is pretty inexpensive, you can change it yourself and avoid those marina labor charges and maybe be able to say "I fixed it myself".

If it doesn't cure it, at least you have an extra coil

Is the retro fit kit the Mallory magnetic breakerless kit that PCM sold?



Originally posted by Lake555 Lake555 wrote:

I just got word from the mechanic at marina that our 91 SN needs the retro kit for the Protec ignition. Ouch!!!



When we purchased the boat one year ago, I was unaware of this know problem with Protec ignition failing in this year of boat. About a month ago, we started experiencing problems with the performance. We would lose power pulling skiers after the engine warmed up. It would start fine but seemed to run rough and not have power to pull skiers. Labor Day weekend we pulled the boat out and took it to the marina. They called today saying the ignition has to be replaced, $500 for kit and $700 for labor!!



Since then I have done some searching and found many posts relating to this same topic. Luckily our carb does not need replaced. Our prior boat was an 80 SN and we never had any engine problems for the 20 years we had it.
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Lake555 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lake555 Quote  Post ReplyReply Direct Link To This Post Posted: August-02-2019 at 11:02pm
I do not know if retro fit kit is the Mallory magnetic breakerless kit, the marina installed it. How can I tell if it is?
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Post Options Post Options   Thanks (1) Thanks(1)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-02-2019 at 11:38pm
Take a picture of the distributor hopefully showing the ID plate on it and take another one with the cap off.

The MBI module looks like the picture below

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Lake555 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lake555 Quote  Post ReplyReply Direct Link To This Post Posted: August-03-2019 at 1:07pm
Ok. the boat is at the lake now, next time I am there I will snap a picture of what you said. Thanks for your help.
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Lake555 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lake555 Quote  Post ReplyReply Direct Link To This Post Posted: August-04-2019 at 11:46pm
Here is a photo. Hopefully you can see it!

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KENO View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2019 at 10:47pm
Can't quite read the label

If it starts with YLM, it's the magnetic trigger distributor.

If it starts with YLU, it's the Unilite optical trigger distributor

They're both good

If it just has a bunch of numbers it's a later version when they were sold to another outfit

A picture with the cap off will tell a lot
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lake555 Quote  Post ReplyReply Direct Link To This Post Posted: August-06-2019 at 10:08am
Sorry for the bad photo. We were short on time and I did not have time to take off the cap. the part number on the label is YLM554CV.    

But I do have some more information. My wife is at the lake and was driving the boat yesterday.   Again, after about an hour of usage, the engine started to sputter. so she took it the marina and had mechanic drive the boat to see what it was doing,   The engine sputtered and coughed for him on acceleration. He looked over the carb and found the choke was stuck and not operating correctly. after he adjusted the choke, engine did not sputter. The mechanic recommends a new carburetor to fix our problem.   Does this sound right to you.?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-06-2019 at 10:20am
Sounds like a money maker for the mechanic

If the choke got adjusted, why would it need a new carburetor?.

It's gonna act up well before an hour goes by if the choke is stuck in the closed position for example.

I'd be asking lots of questions
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 91NaughtyQ Quote  Post ReplyReply Direct Link To This Post Posted: August-06-2019 at 10:20am
I am sure the more seasoned experts will answer, but a rebuild is always a viable option for you on the carb. I did mine last year and it functions like brand new. In short if the choke adjustment fixed the problem and it is running fine now, I don't know that I would do too much to it. Just my thoughts and like I said Keno and the others may have some more sound advice. They are pretty sharp on this stuff and all things CC related. Good luck.

Gary
1991 Ski Nautique
(Previous)1984 Ski Nautique 2001
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lake555 Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2019 at 11:26am
I was incorrect on what the boat mechinac did. He actually manually closed the choke and the sputtering stop. He recommended that they replace the carb.   Does this sound correct??
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2019 at 11:39am
Originally posted by Lake555 Lake555 wrote:

I was incorrect on what the boat mechinac did. He actually manually closed the choke and the sputtering stop. He recommended that they replace the carb.   Does this sound correct??


Short answer is ........................no.

Google "correctcraftfan choke " and you'll find lots of reading about chokes and adjustment.

It should be wide open anytime after about a minute of starting the engine.

It a great source of disagreement here on CCF, but many people have their chokes disabled and permanently open and others adjust per Holley specs.

I'd say you have some carburetor issues and a good cleaning/rebuild is probably needed but don't forget about the ignition system too as a possible culprit.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2019 at 3:58pm
Originally posted by Lake555 Lake555 wrote:

He recommended that they replace the carb.

Marty,
Did he quote a cost for the replacement?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lake555 Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2019 at 4:17pm
Yes the quote was $750 for a new carb and then a couple of hours labor for install, total cost of quote was for around $1,000
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2019 at 4:45pm
I'm surprised Pete hasn't answered you back yet.

He's probably too busy crappin' in his pants.

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Post Options Post Options   Thanks (1) Thanks(1)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2019 at 4:53pm
Not to sound silly, but is the boat still acting up after whatever he did to the choke?

Or is it running good still?



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lake555 Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2019 at 5:17pm
Yes it is still acting up.   It will run good for the first hour. After the engine is running for an hour, then on acceleration, the engine will start to sputter and cough.   We found If we manually hold the choke closed, it will stop sputtering on acceleration.   but when we accelerate without touching the manual choke linkage, the engine coughs and sputters bad. But during the first hour of use, engine accelerates smooth..    we did spray carb and choke cleaner in it yesterday but did not seem to help. Any ideas what to try next?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2019 at 6:38pm
Originally posted by Lake555 Lake555 wrote:

Yes the quote was $750 for a new carb and then a couple of hours labor for install, total cost of quote was for around $1,000

Well, marine mechanics do need to make a living too!


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Post Options Post Options   Thanks (1) Thanks(1)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2019 at 10:18pm
Based on your latest information, I'd check for leaks around the gaskets where the carburetor mounts to the spacer and the spacer mounts to the manifold. And check things like the PCV hose where it hooks to the spacer and the other end where it hooks to the PCV valve too

Do the check when it acts up, not when it running good

You can spray real flammable stuff like starting fluid, less flammable stuff like carburetor cleaner or non flammable stuff like water in a spray bottle and if there's a vacuum leak the engine will change speed as the stuff gets sucked in.

I know what I'd spray

The water will just vaporize and pass right thru the engine.

Closing the choke while you're accelerating is adding a bunch of fuel and making up for extra air getting in somewhere below the carburetor
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lake555 Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2019 at 10:02am
Are you suggesting that you would use water to find the leak instead of the other two options?

if the leaks are causing the hesitation on acceleration, why would it only effect the acceleration after heating up and running for an hour? Wouldn't the leak be there all the time, cold or warm, and effect the engine performance at all conditions?

I am not familiar with the PCV hose and value. can you reference any pictures of this so I know what to look for.   

Thanks for all of your help, much appreciated!!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2019 at 11:20am
I used to use flammable stuff but found that water works pretty well to find a vacuum leak and I can drink it too

It's not as good as the flammable stuff but it works

Things expand , clearances open up a little and the leak shows up. It doesn't take much to affect the idle

Then they cool off, contract and it runs good for a while on cold startup the next time.

Picture coming soon of PCV hose and valve

Originally posted by Gary S Gary S wrote:




Kinda blurry but you can see the hose from the back of the spacer going to the PCV valve in the valve cover

Picture isn't a 351 but you get the idea
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