Cutting out on hole shots?
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=48904
Printed Date: November-27-2024 at 3:05am
Topic: Cutting out on hole shots?
Posted By: Crmaverick
Subject: Cutting out on hole shots?
Date Posted: June-21-2020 at 11:16pm
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This is the last of the kinks to work out on the motor (besides leaky valve seals and a good amount of oil leaking from the oil fill cap) So on my 84 with a Holley 800 and PCM 454 it’s always cut out when doing a hole shot. Problem doesn’t happen when punching throttle after being planed off. Carb is fully rebuilt, I have the idle mixture screws at 1.5 turns and stock jets. I set the float heights on the bench to compensate for the motor tilt (lower front and higher on the secondaries). I tried a quarter turn lower on the front float height, didn’t help, my theory was that the fuel is sloshing back on hole shots and causing a rich problem and it to cut out. Has anyone else has this issue and a good way to figure out the float heights? Or possibly something else? |
Replies:
Posted By: Jonny Quest
Date Posted: June-22-2020 at 12:56am
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First, ensure that your spark delivery system is working well and timing is good. Engine stumbling or bogging down on accelerating is a typical symptom of a problem with the accelerator pump circuit. Below are 2 links to videos showing how to diagnose and tweak the accelerator pump circuit. https://www.youtube.com/watch?v=tMKxD_OFuCA" rel="nofollow - LINK1 https://www.youtube.com/watch?v=k-Nx5HEzvlY" rel="nofollow - LINK2 JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: KENO
Date Posted: June-22-2020 at 9:09am
I hope his spark delivery system is working, he's got one of those JQ approved DUI HEI spark makers Not sure but I think it's even got a RED cap  It's brand new and finally got the timing where it's supposed to be (and he says the problem has been there since he got the boat) Don't forget you have a double pumper (list number 9022) so there are 2 pumps to get adjusted and they have different diaphragms/capacities. Front is 30 cc and the rear is 50 cc I think a video would be good to show the bog/hesitation or whatever and also show how quickly your hand is moving the throttle on takeoff |
Posted By: Crmaverick
Date Posted: June-22-2020 at 9:55am
Yeah that video is a good place to start on the accelerator circuit , the same bog was always there even before the distributor. |
KENO wrote:Posted By: Crmaverick
Date Posted: June-22-2020 at 10:18am
I’ll take a video of it next time, I let my neighbor take it for a ride and pull a skier. She has a mastercraft pro star and noticed the bog out of the hole on my boat just like I was getting it |
Posted By: GottaSki
Date Posted: June-22-2020 at 11:37am
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Its a big mechanical secondary, could it be you may have to be judicious with the go baby go lever and keep it in the primaries till it winds up some? or does it happen even when you do that? ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Crmaverick
Date Posted: June-22-2020 at 2:41pm
The problem is there when I’m just in the primaries. It actually doesn’t happen when cracking into the secondaries. I think it cuts out / bogs around a 1/4 throttle even if that’s the max amount I’m giving it. |
Posted By: GottaSki
Date Posted: June-22-2020 at 3:33pm
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Very good, thats good information. Next, do you recall the primary Mains, and the PV number? ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Crmaverick
Date Posted: June-22-2020 at 5:41pm
Yup I put it all to stock, jets are 72/87 and a 6.5 powervalve. I never even gave the accelerator pump a thought when tuning, other than taking out the slack on the arms. Should I try larger nozzles or different accelerator pump cams to start with? |
Posted By: Crmaverick
Date Posted: June-22-2020 at 7:47pm
Also, both the accelerator pump cams are in position 1. Is that correct or would #2 maybe work better on this motor? |
Posted By: GottaSki
Date Posted: June-22-2020 at 8:56pm
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Difficult to determine remote. Immediate squirt upon throttle movement is best, after that it's flavor to taste. Have you viewed the carb operation under load with SA removed? Good helper required. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: GottaSki
Date Posted: June-22-2020 at 9:07pm
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Nozzles change the duration inversely to volume delivered as a rule. More sooner or less longer. IF it's the squirter, don't dismiss trying a smaller one. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Crmaverick
Date Posted: June-22-2020 at 9:18pm
I haven’t tried looking at it under a load. I found some play in the pump arms today so I took that slack out. Might try the cam position first and then try different squirters and see |
Posted By: KENO
Date Posted: June-22-2020 at 10:20pm
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Watch the videos from earlier and/or read about pump adjustment. But.................You can get all technical or you can do what you just did and adjust the spring loaded screw on each pump arm till it just touches the lever with no slack and you'll almost always be good. Your stock nozzles are .031 inches for both the primary and secondary sides Not too many people change from the factory cam position or change nozzle size so I figure you can get it right without any changes there.
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Posted By: TRBenj
Date Posted: June-22-2020 at 10:45pm
| All good info but remind us again where the timing is set (initial and final). |
Posted By: Jonny Quest
Date Posted: June-22-2020 at 11:09pm
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In the first post, you mentioned that the carb was fully rebuilt. Do you know if the accelerator pumps were also included in the rebuild? The diaphragms can get stretched and lose their pumping efficiency. I see that you also stated that you took some slack out of the pump actuator arm. Good. The accelerator pump actuation must be immediately paired with the throttle. From the Holley website: "What we're really trying to achieve here is the proper relationship between the adjusting bolt on the accelerator pump arm and the actual accelerator pump lever. Ideally, you want that to be zero at idle. By zero I mean there shouldn't be any gap, and it shouldn't have any pre-load. That being said we also want to check it at wide-open throttle and make sure we've got a minimum of 15 thousandths of a gap, as far as available travel left, and that's to make sure we don't bottom out that pump diaphragm." Just for giggles, it would be interesting to see what your vacuum is reading at idle. That can help you understand which power-valve you may need. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: Crmaverick
Date Posted: June-23-2020 at 12:23am
I have it at 12 initial and getting 36 total for timing. Pump diaphragms were replaced. I should hook my vacuum gauge up and check that, I have a 6.5 power valve in there now and 4.5 valve in my spare parts box |
Posted By: Crmaverick
Date Posted: June-23-2020 at 12:26am
| Anyone else running position 2 on the accelerator pump cams? |
Posted By: GottaSki
Date Posted: June-23-2020 at 7:18am
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You have a fairly unique case here, herd response will likely confuse things. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: KENO
Date Posted: June-27-2020 at 2:10pm
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Call off the herd Mav sent me a "bog free video" after the accelerator pump clearances were adjusted. |