Hesitation on acceleration under load
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=698
Printed Date: November-25-2024 at 7:06am
Topic: Hesitation on acceleration under load
Posted By: cinekw
Subject: Hesitation on acceleration under load
Date Posted: August-05-2004 at 1:38pm
1980 Ski Nautique with 351, when pulling out of the whole with gradual acceleration I can feel the engine pull and hesitate and pull again, it feels like the engine miss fires, this happens until you get to a certain speed but when accelerating fast it's fine.
What could be the problem.
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Replies:
Posted By: Guests
Date Posted: August-13-2004 at 2:22pm
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still having the same problem with my 93 pro boss. for about 14$ you might try anti-syphon valve as the ball can get gunkd up and not let fuel in. its in the 3/8 hose that connects to gas tank. mine does not do it everytime so classified as a gremlin. im thinking accelerator pump or other part of carb. sounds like not getting enough gas when it needs the extra squirt on take off. do you have points and distributer. the tiniest hairline crack around the bottom edge of distributer can cause same symtoms. also corroisen from condensation in distributor can cause it. you might sand all contacts in distributer until you can get a new one so that it is shiny metal on contacts. sand roter as well. that use to fix my old ski centurion all the time.
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Posted By: cinekw
Date Posted: August-16-2004 at 11:46am
It doesn't happen all the time on mine either, I have the distributor and I already checked the cup, roter and plugs all look fine. It does it after about half hour being on the water and only when under load. I will try to take off the fuel filter to see if its restricting the gas flow too much.
Thanks
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Posted By: WRoll
Date Posted: August-16-2004 at 5:49pm
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The problem you are experiencing is very common and you should be able to resolve the problem by rebuilding your carburetor.
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Posted By: 64 Skier
Date Posted: August-18-2004 at 2:12am
If I read your post correctly:
Slow acceleration hesitates.
Hard accelaration or WOT is good.
Doesn't sound like a fuel "restriction" or the condition would be worse at WOT. Sounds like the Primaries in the Carb.
Check the Choke operation.
Your carb has an Accelerator Pump and Power Valve (Holley) that smoothes the transition from idle to WOT. Sounds like they're working fine. During slow acceleration, your fuel is mainly from the Idle mixture and Primary circuits.
To make sure the Accelerator Pump is working, look into the carb and pump the gas and make sure she "squirts". Easy part is over...
Then I'd suggest you check the setting of the idle mixtures first...typically 1 1/2 to 2 turns out and then fine tune for max engine vacuum or RPM. If you can, reset the Idle to 800 RPM and then check your engine timing. At this point, you know the Idle Mixture is correct, Timing OK and Power Valve and Accelerator pump working.
After that, a slow acceleration depends on the primary jet size or debris in same.
Lot of guy's here run Holleys...if you do dig into the thing, post your jet sizes and power valve spec's and you'll get some great input. Hopefully, this post will stir up some of the Carb Guru's...I think that's your problem.
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64 Skier
66" HO VTX and 67" HO Triumph
http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC
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