violent vibration over 2000 rpm
Printed From: CorrectCraftFan.com
Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=39658
Printed Date: May-07-2024 at 11:45am
Topic: violent vibration over 2000 rpm
Posted By: 1xsculler
Subject: violent vibration over 2000 rpm
Date Posted: August-13-2016 at 7:52pm
|
'94 Ski Nautique, 351W with throttle body injection, idles well, runs smoothly up to about 2000 rpm and then proceeds to vibrate violently, almost like it's running on only 1/2 of the V-8, as you increase the speed. When I give it full throttle it accelerates quickly and smoothly for a few seconds and then dies back to a slower speed. I just changed all of the spark plugs. There's no water apparent in the oil. Oil pressure and water temp seem normal. I don't believe the prop or shaft are bent which would be evident at idle to 2000 rpm or on full acceleration. The next thing I'm going to check is if all four injectors are spraying fuel as the throttle is applied. Like I said, it feels like only 1/2 of the engine is running when it starts to vibrate violently. |
Replies:
Posted By: Dreaming
Date Posted: August-13-2016 at 8:22pm
| check to see if you have all your plug wires in the right order? sounds like you have 2 reversed. My motor does this currently (see my engine rebuild questions) but it is due to the 4 and 8 cylinders being at 80PSI compression... |
Posted By: 1xsculler
Date Posted: August-13-2016 at 9:30pm
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Might it be contaminated fuel as my daughter had just installed ten gallons? If plug wires were crossed wouldn't it run poorly through out the rpm range? |
Posted By: 1xsculler
Date Posted: August-13-2016 at 10:53pm
| I installed the new plugs AFTER the first episode of this problem. |
Posted By: GlassSeeker
Date Posted: August-13-2016 at 11:11pm
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Check the distributor cap for moisture and corrosion ------------- This is the life |
Posted By: GlassSeeker
Date Posted: August-13-2016 at 11:12pm
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Bad fuel would be bad at all rpms ------------- This is the life |
Posted By: halfnelly
Date Posted: August-14-2016 at 3:32am
| Since you have a 94 with TBI, it could be the ProTec ignition module finally going bad. If that's the case, your best bet is going to be converting it back to a carb with a conventional distributor and coil as ProTec replacement parts are nonexistant. I got rid of the ProTec on my 94 a few years ago and it's never run better. Lots of other members have done the same swap with great success. |
Posted By: judyfifacoins
Date Posted: August-14-2016 at 4:10am
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Posted By: 8122pbrainard
Date Posted: August-14-2016 at 8:26am
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Bob, Does it run rough with no load as well as under load?
I agree with Brian that the Pro Tech would be suspect. I feel you may get some indication of an ignition issue by using a timing light above the 2000 when it starts to run rough. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
halfnelly wrote:Posted By: desertskier
Date Posted: August-14-2016 at 9:58pm
| Looks like you have several threads going. Is the red dash light still on? If so you are probably in limp mode which may be causing the vibration. If your gauges indicate that you are not overheating and have good oil pressure then you probably have a bad switch. I would disconnect both the oil pressure and temp switches on the engine and see if the problem goes away. The protec will go to limp mode if either of the switches activate. |
Posted By: 8122pbrainard
Date Posted: August-14-2016 at 11:02pm
Bob, http://www.correctcraftfan.com/forum/forum_posts.asp?TID=39652&KW=&PID=512167&title=red-warning-lit-on-dash#512167" rel="nofollow - Here's your thread on the warning light I suggest keeping like problems together in one thread since they may actually be the same problem. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 1xsculler
Date Posted: August-15-2016 at 2:45am
|
Two different boats. '94 Ski Nautique, 351W, TBI, Protec, no red light, severe vibration above 2800 rpm, probably going into Limp Mode and or Protec failing. '95 Sport Nautique, 351W, GT-40, multiport EFI, occasional red warning light on dash but everything else seems good, i.e. runs perfectly. I'll try disconnecting oil press and temp switches on the '94 tomorrow to see what that does before ordering a distributor and carb. |
Posted By: desertskier
Date Posted: August-15-2016 at 11:53am
| Also, the protec module needs good battery voltage at the input or it won't function correctly. Check the voltage at the 12.5A breaker on the back of the engine. It should be close to battery voltage. If it's low then you probably have some IR voltage drop through the dash wiring. |
Posted By: 1xsculler
Date Posted: August-15-2016 at 6:00pm
| Problem solved....see THANK YOU 2800 rpm vibration solved. |
Posted By: spiralhelix
Date Posted: August-15-2016 at 6:20pm
making it easier to finish the thread.
------------- -Spiral '89 Sport Nautique |