Carburetor issues
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=43087
Printed Date: October-06-2024 at 2:27pm
Topic: Carburetor issues
Posted By: shierh
Subject: Carburetor issues
Date Posted: July-05-2018 at 11:49am
| I have been dealing with rich running for the last year or more. Never considered it was bad carburetor since it was new not rebuild. Well i shut off both low speed jets and it stayed running. Has some internal leak or defective power valve. Fortunately i have a spare and will put it on this weekend. Spare I rebuilt and ran so i know its good. |
Replies:
Posted By: TRBenj
Date Posted: July-05-2018 at 12:18pm
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Or your fuel (tank/lines/filter) has junk in it and plugged up the idle circuit. |
Posted By: shierh
Date Posted: July-05-2018 at 12:35pm
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Not possible. Tank is clean and filter is only a couple of years old, (tall water separator and filter.) This boat was a complete restoration and i replaced everything. I have 88 hours on the engine. No ethanol use and i keep MMO in the fuel. |
Posted By: KENO
Date Posted: July-05-2018 at 2:11pm
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Maybe to paraphrase Tim's comment a little. Are you sure you're idling on the idle circuit in the first place or are you idling on the transition slots because maybe your idle circuit isn't flowing like it should.? Notice I said nothing about junk or plugged up passages 
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Posted By: shierh
Date Posted: July-05-2018 at 2:38pm
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No idea Keno. Have a spare so will try it. Plan to get a kit and go through the "new one" Story is that i use to own this project with a friend who knew nothing. I built original carb and it worked well, However there was a vacuum leak on base gasket and he got scared and convinced me to get new one. Well the fing new one was never any good, It backfired all the time until warmed up. No it wasnt timing. It did however quit backfiring but has been running very rich, plugs are black and smokes bad on start up. Fact is that i had a base gasket leak once again for the ruckus on the river event and it actually ran better. I need to put locktite on the base nuts. Well i got rid of the boat partner last year and finished the restoration etc. This is the last remaining issue that im aware of. |
Posted By: shierh
Date Posted: July-06-2018 at 12:09pm
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Swapped carburetors last evening. Fired on trailer. only ran a few seconds since did not hook up water. What a difference. If it isnt raining this evening im taking it out and do final tune and see how it does. what gap do most set the choke butterfly? im guessing 3/16" |
Posted By: KENO
Date Posted: July-06-2018 at 1:21pm
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3/16 sounds reasonable. Here's a little light reading about choke adjustment with plenty of disagreement on the subject You must have missed it http://correctcraftfan.com/forum/forum_posts.asp?TID=43019&PN=2&title=hard-to-start" rel="nofollow - link |
Posted By: shierh
Date Posted: July-06-2018 at 2:11pm
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that was informative. Bunghole care is important. Im guessing summer setting would be wider than winter Last thing, besides power valve leak is there anything else that would cause the excessive fuel with slow speed screws shut off? |
Posted By: TRBenj
Date Posted: July-06-2018 at 2:42pm
| Floats too high, debris in needle and seat, plugged idle circuits combined with excessive curb adjustment (running on transition), etc. Most of the common “time for a rebuild and clean the fuel system while I’m at it” stuff. |
Posted By: shierh
Date Posted: July-06-2018 at 3:34pm
| I was bad out of the box, it was new not a rebuild. |
Posted By: KENO
Date Posted: July-06-2018 at 3:50pm
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There are some variations on power valve issues. A power valve leaking by it's seating surface really has no effect on idle richness but ................... a power valve with a ruptured diaphragm gives a direct path for gas right from the float bowl to the intake manifold.through the manifold vacuum chamber of the carburetor A bad or wrong power valve gasket gives the same results as a blown diaphragm. If your accelerator pump transfer tube has a bad (or missing) o ring on either end, you'll get the same effect as a blown power valve only it's drawing gas from the accelerator pump circuit, into the vacuum chamber and into the manifold. And it wouldn't be the first carburetor that was bad out of the box |
Posted By: shierh
Date Posted: July-06-2018 at 3:59pm
| OK will look at these when ever i open it up |
Posted By: shierh
Date Posted: July-08-2018 at 10:23am
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Put on old carb and found same issue, observed primary jets dripping. Ran in the low speed jets and dripping increased. Backed them out an it decreased but never stopped. Pulled bowl and verified power valve was good. no issues found. Float was set at the level the manual said. I did however take the 7/16 bit and set the low spot on the float to this level. Ran it on trailer and no dripping. I took bowl off of the new carburetor and set the primary side float to the same level. Now i will say that while using the old carburetor i got significantly more power , almost 4800 , just ran like crap at slow speed. Ill lake test next weekend. |