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57 four barrel floods after shutdown

B

baytro23

Regular Contributor
"1994 starts easily, runs fine

"1994 starts easily, runs fine, problem is when I cut it off then try to restart I have to open the throttle fully to get it to fire. I know a carb rebuild should take care of the problem, my question is what specifically in the carb is the problem? I guess raw fuel is leaking out of the bowl into the intake??? What causes this? Not the float/valve is it? That controls the fuel getting into the bowl."
 
First you will have to tell us

First you will have to tell us the particulars. I'm already thinking it's a Holley. What engine etc.? Al W. (There is an aanswer).
 
After Guys comment I would off

After Guys comment I would offer that a complete rebuild is in order. As with any older Carb. you will be wise to find a reputable re builder who understands the need to update older Carbs. with manufacturer prepared update kits. Not only for modifications but for use with ethanol added fuel/gas. Al W.
 
"Hey Baytro23 maybe this can h

"Hey Baytro23 maybe this can help .http://www.bdub.net/manuals/Quadrajet_Service_Manual_1981.pdf
If it looks like this then it is a quadrajet. I am not understanding when you say I have to open the throttle, do you mean the choke? Have a merc tech determine if the carb is truly the issue. If it is, then my advice is to have a carb pro rebuild it, not a marina that just uses a carb rebuild kit. I am in no way trying to be a wise guy when I say do not try on your own to rebuild this carb.DO NOT TRY THIS."
 
baytro23
On the underside of

baytro23
On the underside of the Rochester float bowl there are two plugs staked in under the main jets. These plugs had a propensity to leak the fuel out of the bowl. An epoxy fix was the remedy I believe.
Bert
 
"a little more info:
*hav

"a little more info:
*have to open throttle fully to get it to fire means - when engine is warm, I have to push the neutral button in then push the engine speed lever towards the bow of the boat until it stops, the lever is in a general horizontal position at this point, once it fires I quickly return the lever to its straight up "vertical" position.

*It's not a Holley or a Mercarb, my Clymer manual which covers 1986 - 1994 Mercruiser Alpha One, Bravo One, Bravo Two, and Bravo Three lists 4 differant carbs for these years. The Mercarb for those years are 2 bbl. only, so the possibilities are Rochester 4MV 4-bbl. or Weber 4-bbl. Looking at the pictures and going by memory (the boat is 2 hours and 15 minutes away) I believe it to be a Rochester quadrajet and not the Weber.

*Bert,thanks for reading my post correctly, that was the kind of answer I was looking for, thanks. To the others that reaffirmed my thoughts on a carb rebuild solving the problem, thanks, but my question was what specifically inside the carb is likely the problem that is evidently allowing fuel to leak out of the carb and into the engine after shutoff causing the flooded condition? As far as I know a carb rebuild is little more than disassembly, dumking the metal in parts cleaner for a day or so, then reassembly with a few new parts and gaskets. Will clean metal stop the leakdown? New gaskets?"
 
"baytro, Your description of a

"baytro, Your description of a Carb. rebuild is way over simplified. I and at least one other poster specifically said that a rebuild by a known expert re builder is in order. Your fooling yourself if you think the average mechanic can do justice to a rebuild and upgrade. Just knowing where to look for the required parts/kits is an art by itself. Spend the bucks before you damage the internals of your engine. Al W."
 
"Al, please don't take thi

"Al, please don't take this the wrong way, I'm just communicating with you civily. If you go back and read the original post I said "I know a carb rebuild should take care of the problem, My question is what specifically in the carb is the problem?". Never did I say I was going to get some jackleg to rebuild it or even attempt it myself, I'm simply trying to understand what "exactly" within the carb causes the problem. If you don't know that is fine. I myself do not know what causes this condition. I wanted someone to say that condition is caused by the _________ and if you get a qualified person to do the rebuild it will certainly take care of your problem. Or, I had that same problem and the rebuild only lasted 6 months and I was back to square 1 and ended up buying a new carb. If the problem is caused by worn parts that get replaced during a rebuild then the rebuild should be as good or better than new. If I'm gunna end up buying a new carb then I would rather not waste money on a rebuild."
 
"baytro23, From the first post

"baytro23, From the first post it seems that you have no difficulty starting the engine when it is cold. So that makes me believe that there is fuel in the bowl. If the bowl were empty then there would be a difficulty on a cold start. I dont think that the bowl would empty so quickly after the boat is run. From my experience it would take a day or so for that to happen. If you crank the boat several times after a run ( the engine is warm)and you have to throttle up completly so that it starts makes me think that fuel is being delivered to the carb and that it is flooding( thats why you have to throttle it to start it.) I would look into the choke, My 5.7 is an older version and I have a divorced choke on it. I had the same type of problem, I changed the choke spring and it seems to run fine. It could be that the choke butter fly on the top of the carb is remaining closed after a run and the engine is getting flooded when you try to re-start it. Take off the carb cover and the flame arester, run the engine from a cold start, watch the choke butter fly it should open when the engine is completly warm. (say 140-150 degrees.) shut the engine off, wait and try to restart it. If the choke remains closed at this point then you have insight into where to look. Hope this helps."
 
"Bert gave you a pretty good e

"Bert gave you a pretty good explanation from his experience w/o seeing the carb. If the carb is original then it's likely that it has some worn bushings, etc. and would need prof. remanfg. I suggest that you buy a Merc. remanfg. carb from a reliable source or send yours out for the work.

This # may be your carb: 1347-816373A 4 You'll need to match the numbers from the side of the carb and the carb ID alum. tag attached to a screw to make sure you get the correct carb. A new or remanfg. carb is avail. from this site for about $550-650."
 
"baytro, All too often Diagnos

"baytro, All too often Diagnosis becomes a game of Paralysis by Analysis. My answer's to your situation are offered in good faith and fraternally. I am of the opinion that a Carburetor is a dangerous component which is capable of catastrophic harm. Lives have been lost due to a Malfunctioning Carb.. My intent in answering was/is to pass along what little knowledge or experience I have in a fashion that this is understood. Suggestions of a new Carb. are good though I suspect pricey. A good rebuild with accurate diagnosis should be around $250. Good Luck with your Carb.. Respectfully, Al W."
 
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