Vapor Lock / Blower Replace / Gas Tank Removal
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Boat Maintenance
Forum Discription: Discuss maintenance of your Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=47692
Printed Date: April-29-2024 at 5:39am
Topic: Vapor Lock / Blower Replace / Gas Tank Removal
Posted By: BoyceByerly
Subject: Vapor Lock / Blower Replace / Gas Tank Removal
Date Posted: July-07-2019 at 6:29pm
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I apologize for the completely crazy header, but if you're curious, well read on. I'm having trouble with my '79 Correct Craft Mustang Inboard. (This is a 302 Ford V-8 with a 4 barrel Holley and a V-drive). This problem goes back into last season, before I had the engine rebuilt. Once the boat got warm (10 minutes or so), and we were ready to hit the water, the boat would start to stall, or, mostly, just chug and sputter, and not get much past 15 mph, and then sometimes die. The boat runs GREAT for the first ten minutes. It's especially bad after getting to the 'right' skiing spot, cutting it off, and restarting. My thought was vapor lock. I've talked to some much more knowledgeable people (not hard, in my case), and they agree. The suggestion was to verify the blowers are working properly, and try and run them ALL the time, to keep the engine compartment cooler. (I only ran them prior to starting before, as a safety measure, not as a temperature control measure). I check the blower, and what do you know, it's come loose from its mounting, so it's just moving air around in the bilges, not sucking it out of the boat. Fixing the blower is the subgoal here. On this boat, there's a bench rear seat. If you remove that, the gas tank is in the lower part, with about 8" above it, and the blower connecting straight to the rear-facing vent scroop on the rear deck -- held into the wooden deck with 4 stainless screws. Two screws were missing entirely, and one was pretty wallowed out, so it isn't hard to see why the thing had fallen off. There's a 3" hose, about a foot long, that goes down behind the gas tank, and another one, that comes off the other (passive) vent, that goes, again, down behind the gas tank. My proposed fix is to reattach the blower, and add a longer hose to the intake so it's sucking air from the engine compartment, to more directly address the temperature problem, and test to see if the problem goes away with constant effective blower usage. Here's my problems/questions: 1) The blower is really annoying to reattach -- nothing difficult in theory, but those practical issues about having to screw in screws where you can't see them, left handed, awkward angles, holding the blower in place while trying to put in screws one handed, etc. I've also got to line up the slots on the blower with the old holes, or drill new ones, but with the amount of space and visibility, this is REALLY difficult -- I worked on it for a couple hours today, and got nothing done except swearing and getting covered with grease. After meditating on this for awhile, the best improvement I could think of was getting a sand bag to support the blower on while doing this, which seems like a little extra help, but not that much. 2) It looks to me like the original install of this was done prior to the installation of the fuel tank, which would make the whole process fairly easy with the extra maneuvering room. Anybody ever loosen and move the fuel tank? My guess is that getting the fuel tank out of the way is difficult and tricky to do, and this is a stupid idea, but my frustration level with #1 is getting so high, I'm considering it. 3) I'm attaching a longer (~6ft) intake hose on the blower. I initially wanted to attach the longer hose on the other side (sucking air from the passive vent). My reasoning was that I was afraid the longer hose might get some "slosh' from the bilge. While I don't think any 'slosh' water would make it up the whole six feet to the blower, I didn't want any moisture going through that blower motor. I changed my mind because there's a lot less room on the other hose to make this modification. Should I go to some extra effort, or abandon this modification? 4) Does my whole general plan make sense? Is there some other fix, or test, that you would consider prudent prior to me proceeding? (I guess reattaching the blower is a no-brainer, must-do repair, but still, I'd be interested in hearing what people have to say.) Thanks for any thoughts or advice! -Boyce ------------- Boyce Byerly Owner of a '79 Mustang |
Replies:
Posted By: GottaSki
Date Posted: July-07-2019 at 6:47pm
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Oh, yes best pause the bilge blower Kabuki dance Firstly get vapor lock out of your mind, just not happening. Not hot enough. If it was, you would have other bigger problems like burned up mufflers and sinking. Dollars to donuts you have a fuel delivery restriction you are associating to temperatures only coincidentally. Likely restricted at the tank outlet pickup tube from debris ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: 8122pbrainard
Date Posted: July-07-2019 at 6:50pm
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Boyce, Your plan does not make any sense to me. Vapor lock is almost unheard of in marine and highly unlikely. There are thousands of boats out there that do not need a blower running to cool the engine compartment. The blower is there to exhaust potential gas fumes. Unlike automotive, the marine engine has an unlimited supply of cooling water from the lake. I suggest not talking to the person who thinks vapor lock.  You said the engine was rebuilt. How about the carb? Can you see fuel dripping down the carb throat (flame arrestor removed)? Does the exhaust smell like the engine is running a rick mixture of fuel? The tank can be removed after the fill ,vent wiring and hold downs are removed. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: KENO
Date Posted: July-07-2019 at 7:50pm
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Assuming that you're going to put the blower back in place the hardest part of removing the tank is getting the fill hose off The easiest way is to remove the 3 machine screws holding your fill connection to the rear deck, loosen the hose clamps on the fill line and then pull the fill connection up and out of the way. Then you can pull the short fill hose and remove it through the hole where the fill connection was. If the hose has been there for 30 years, it might be like wrestling a bear and it might also be time to replace it  After that the vent hose, wiring to the sending unit and the hold downs will be a piece of cake. When the tank is slid forward or removed, then you can check the pickup tube and the anti siphon valve hooked to it to be clear. (you could also do this with the tank in place) The anti siphon valve is a check valve that's spring loaded shut and only opens when the fuel pump is sucking fuel through it. It looks like a barbed hose fitting and the only good way to check it is to unscrew it and see if there's junk plugging it. While it's out you can then blow air into the tank through the pickup tube to be sure it's clear So removing the tank isn't a stupid idea at all
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Posted By: BoyceByerly
Date Posted: July-07-2019 at 9:33pm
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Thanks for all the good input! I'll look harder for a fuel restriction, but.....this really is temperature related, to my mind. Does anybody have any fuel restriction theories that are temperature related, that wouldn't occur with a cold engine? Regardless, the blowers NEED to be fixed, so we'll see if that helps, I suppose. -Boyce ------------- Boyce Byerly Owner of a '79 Mustang |
Posted By: 8122pbrainard
Date Posted: July-07-2019 at 9:41pm
Not temperature related but time related on the restriction. As time goes on, junk is being sucked into the anti siphon and or the fuel pickup tube in the tank. Then when the engine isn't running the junk settles back into the tank. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
BoyceByerly wrote:Posted By: KENO
Date Posted: July-07-2019 at 10:47pm
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Call me crazy or whatever, but if you think it's temperature related , drive it around with the engine box open and see if anything changes. You'll have plenty of cooler air flow around the engine No kids, pets or stray body parts allowed near the spinning stuff though
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Posted By: ViperSammy
Date Posted: August-13-2019 at 5:40pm
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Hi everybody, I am a new Nautique owner, and therefore new to the forum. I have searched several places for issues similar to the one being described by the OP. And, most everyone agrees that vapor lock is extremely rare on marine engines, and I can see why that would be true... but, I am experiencing similar issues with my '85 SN 2001 with the 351 Cleveland. Starts and runs great until I drive it for a while, then it is hard to start, and doesn't want to idle, or accelerate unless given lots of throttle. The theory of the gas tank picking up trash is no good to me because I just had to have my tank repaired, (fill tube weld broke) and it was doing it before and is still doing it. So, I don't steal this thread, I will start a new one titled: 85 SN 2001 rough idle, no acceleration after warm. Sorry for the intrusion, I hope you find your fix Boyce, I will be checking back. Scott ------------- '85 Ski Nautique |