stalling at 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=43335
Printed Date: October-06-2024 at 12:27pm
Topic: stalling at idle
Posted By: smac76
Subject: stalling at idle
Date Posted: August-05-2018 at 11:40pm
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Started having an issue this morning with my 76 SN. Dropped it in this morning for the first time this season. Started fine, took it up to speed for a couple laps around the lake, and brought it back to the dock to use later. Went to go for a ski an hour later and I couldn,t get the boat to idle below 1100-1200 rpm. It idles high when cold and I gradually bring the rpms down as it reaches temp and the auto choke opens, but now it just cuts out and stalls/shuts off when I try to get it to idle normally. Then I cant get it to start until it sits for a while, almost like its flooded. If I go to start it 45-50 minutes later, it starts right up, but again, it wont idle. It just shuts off when I bring the throttle back to idle. I have maybe 7-8 hours on a freshly rebuilt Holley carb going back to last season- this was my first time in the water this season. Could my issue be as simple as the old gas, even though it was stabilized for winterization? A mechanic friend of mine explained to me that I may have a stuck float, which can cause the engine to act like its flooding, or some kind of blockage or vacuum leak in the low idle circuit. Suggestions? ------------- It's 5 o'clock somewhere... |
Replies:
Posted By: MACS81SN
Date Posted: August-06-2018 at 8:15pm
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Looks like this post was overlooked. Get engine started and let run briefly. Shut down and remove flame arrestor. Look down front barrels and see if gas is dripping down carb throat. Is so then you have some carb flooding issues. Fuel level too high, something in needle and seat, bad float. Less likely but possible is a leaking fuel pump diaphragm. I believe the 76 was equipped with a little clear tube from the flame arrestor to fuel pump. Check for gas in this tube which would indicate a fuel pump diaphragm leaking. The idea here that if it is leaking it will be dumped into the carb and not collecting in the bilge. You seem to indicate all was well after the carb rebuild? If an auto parts store base gasket was used under the carb adapter plate it won’t fit properly. It may start off okay but can cause a vacuum leak later. Need a PCM gasket or home made one to fit better. A lot of guys here claim to get bad gas. I’ve had Correct Crafts for 40 years and put 7500 gallons thru our 81 with never a gas issue plus a few 1000 thru a couple pontoons and a fishing boat. Maybe gas is better in this part of the country or handled better. ------------- Mark 1999 -SN - 502 Python 1981 - SN Owned 33 years - Sold 1968 - Mustang - Sold |
Posted By: Bri892001
Date Posted: August-06-2018 at 8:24pm
| You said the electric choke does open up ok? |
Posted By: smac76
Date Posted: August-06-2018 at 9:48pm
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I didn't look when it was warmed up, but when I couldn't get it to restart I gave it a shot of ether to see if that would get things going and I don't remember seeing anything dripping into the venturi. In fact I thought it may not be getting any gas, but that was proved wrong when after sitting for a little while it would start right up. As far as the choke opening up, it is definitely opened all the way. It may only be closed upon the initial firing as when I got to checking for fuel in the engine both barrels are wide open. I can't remember where the base gasket came from when I put the carb back on, but I don't think I ever told anyone it was for a PCM motor. It just kind of was for a Holley 600. I haven't been able to check for vac leaks, but my mechanic friend also mentioned that, so that's on my list. ------------- It's 5 o'clock somewhere... |
Posted By: MACS81SN
Date Posted: August-06-2018 at 10:23pm
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Not sayin the gasket is your issue but it sounds exactly like one I worked on some years back. Carb had been rebuilt and automotive gaskets used under carb and adapter plate. Ran ok for short time and then wouldn’t idle below 12-1500 rpm and was hard to start. After some head scratching, finally found, side of gasket under adapter plate was sucked inward, leaving a gap, because there wasnt enough material to clamp it solidly between adapter and manifold. Unless you make gasket yourself, you’ll have to get from PCM supplier like SkiDim, Nautique Parts or local CC dealer. Automotive types aren’t quite wide enough. You could try carefully spraying your starting fluid around the carb/adapter base while it’s running and see if this affects idle. Unlit propane torch open fully might work too. You just want to temporarily enrich the lean condition. If doesn’t make a difference then may not be the problem. ------------- Mark 1999 -SN - 502 Python 1981 - SN Owned 33 years - Sold 1968 - Mustang - Sold |
Posted By: smac76
Date Posted: August-22-2018 at 10:35pm
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Mac- when you say "not wide enough" do you mean on the flat? Or did you mean that its not thick enough? between carb and adapter? ------------- It's 5 o'clock somewhere... |
Posted By: KENO
Date Posted: August-22-2018 at 10:50pm
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What he means is not wide enough on the flat. About a year ago you had a stalling problem and replaced both gaskets and cured your problem.. The bottom one is the one that can easily give issues if it was replaced with one that wasn't wide enough even if it was just replaced last year and worked well at that time. The PCM gaskets are wide and also pretty thick which helps too. Like Mac said, PCM gasket or cut your own for the spacer to manifold joint. |
Posted By: KENO
Date Posted: August-22-2018 at 10:55pm
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You could pull the carburetor and check the gaskets Here's a link to the PCM gaskets https://www.skidim.com/GASKET-CARBURETOR-SPACER/productinfo/RM0054B/" rel="nofollow - link |
Posted By: Gary S
Date Posted: August-23-2018 at 12:26am
Here is what the underside of that spacer looks like,this is the vacuun source for the PCV on the valve cover- This is the gap that caused by using a standard 4 bbl gasket,you can move it a little so that it looks like it closes the gap but being under high vacuum will leak soon.  This is a PCM gasket,you can see how much larger it is. So far I have not found a readily available aftermarket gasket that fits.  . ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: smac76
Date Posted: August-23-2018 at 8:10pm
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That makes sense. My stalling problem was rectified after I did a carb rebuild, and overall the boat ran much better, but I wonder now if that was just due to the new gasket I used when I put the carb back on. Well, the rebuild couldn't have been a bad thing. It IS 42 years old. Any-who, gonna order up one of those new PCM gaskets. I'll let you know how it works out. Thanks, ------------- It's 5 o'clock somewhere... |