New primary fuel bowl, new (not great) idle
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=50929
Printed Date: November-22-2024 at 2:32pm
Topic: New primary fuel bowl, new (not great) idle
Posted By: uncle-buck
Subject: New primary fuel bowl, new (not great) idle
Date Posted: October-02-2022 at 7:56pm
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Installed a new primary fuel bowl on my boat's Holley carb yesterday. The new bowl looks virtually identical to the old bowl (purchased as part of the current carb in 1995), but the float did not sit level as it had previously. Adjusted it to level and the boat started, but not easily. Took it out on the river today and it runs well overall, but the idle is definitely off a little. Any ideas on what would change the idle circuit characteristics under these circumstances? Should I re-tune the idle circuit using a vacuum gauge? Any other ideas/suggestions? ------------- 1990 Ski Nautique (original owner) PCM 351W with D.U.I. |
Replies:
Posted By: MechGaT
Date Posted: October-02-2022 at 8:21pm
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I made the same swap and am having some issues as well. I thought the level might need to drop a bit as I was seeing a bit of gas on the throttle plates after shutting it off, but after adjusting the floats again the leaking seems to be worse. I am interested to see what you figure out. When you say not great idle, what do you mean? Does it seem like it is starving for fuel or flooding? Do you notice a difference in the exhaust look or smell? I would say it can't hurt putting a vacuum gauge on it, but I am not sure why the idle circuit would have changed. Perhaps someone with more knowledge will be a long shortly and give us both a lesson. ------------- '92 Sport Nautique |
Posted By: uncle-buck
Date Posted: October-02-2022 at 10:23pm
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I can't tell whether it is starving or flooding, but am now wondering if the bowl gasket got boogered up when the new bowl was installed. One of the bowl screws didn't slide into place easily during installation and may have gotten caught and torn that gasket. Easy enough to check tomorrow. ------------- 1990 Ski Nautique (original owner) PCM 351W with D.U.I. |
Posted By: KENO
Date Posted: October-03-2022 at 8:02am
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Did you transfer all of the parts over to the new bowl, like the gasket between the inlet seat and the bowl? Since you're taking the bowl off, you can check to make sure the coil spring is im place correctly and the little wire retainer that insures that the needle goes up and down with the float is installed right. You can also check that the little circlip that holds the float on it's pivot arm didn't fall off
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Posted By: uncle-buck
Date Posted: October-03-2022 at 11:18pm
------------- 1990 Ski Nautique (original owner) PCM 351W with D.U.I. |
KENO wrote:Posted By: uncle-buck
Date Posted: October-04-2022 at 11:03am
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Everything in the primary bowl looks fine. Replaced and started the engine. Idle was ok for a few seconds and then got very rough. Looked in the carb and saw fuel (a lot) dripping into the secondaries! Will search these forums for a solution. In the meantime, any advice would be much appreciated. P.S. How critical are these plastic fuel inlet baffle plates?  ------------- 1990 Ski Nautique (original owner) PCM 351W with D.U.I. |
Posted By: uncle-buck
Date Posted: October-04-2022 at 12:39pm
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OK. it appears the idle issue was unrelated to and coincidental with installation of a new primary fuel bowl. Found fuel dripping from the secondaries. Cleaned the needle in the secondary bowl and blew compressed air through the seat and bowl inlet after separating the seat. Reassembled, installed a new float and all is now well.
------------- 1990 Ski Nautique (original owner) PCM 351W with D.U.I. |
Posted By: KENO
Date Posted: October-05-2022 at 7:31am
Since google lens says that's not a picture that Buck took, why are you wondering? Did you break yours? They're supposed to help prevent foaming in the side hung fuel bowls according to one Holley book I have.
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Posted By: uncle-buck
Date Posted: October-05-2022 at 7:44am
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When I transferred the old one to the new bowl, it was a very awkward and tight fit. I thought it might have been restricting fuel flow, so I left it off and ordered a new one from an eBay seller. Did not see it on Holley's website and wondered if it is even included with the newer carbs. ------------- 1990 Ski Nautique (original owner) PCM 351W with D.U.I. |
Posted By: KENO
Date Posted: October-06-2022 at 7:22am
A smart person would install the new one when you get it.  A not so smart person would have removed the one from the rear bowl too. Here's a quote from another Holley book " this baffle is essential for fuel level control and must be reinstalled into the bowl. Fuel flow will not be increased by leaving it out"
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Posted By: uncle-buck
Date Posted: October-06-2022 at 8:35am
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Good info. Thanks for sharing. ------------- 1990 Ski Nautique (original owner) PCM 351W with D.U.I. |