Sporadic Miss - Vapor Lock?
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=11854
Printed Date: September-29-2024 at 1:31pm
Topic: Sporadic Miss - Vapor Lock?
Posted By: Gleno4224
Subject: Sporadic Miss - Vapor Lock?
Date Posted: September-05-2008 at 12:40am
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First off - let me say this is an awesome site - I've read tons of posts and learned alot.
I have a 1978 SN with a 350 OMC engine. I have been chasing a number of problems this summer. My biggest concern has been this: When cold - boat runs great - no problems - but after I've run it for 30 minutes or so - come back to dock and shut her down - then idle back back out - stop to let a skier or tuber in the water - the engine will not start back - it'll turn over - just not fire - after repeated tries I can usually get her going again. At first I was thinking electrical - A prestolite breakerless ignition was installed several years ago - I replaced the coil early this summer to rule that out. I started looking at the fuel system - and have replaced everything from the tank to the carb, new fuel line (rubber fuel grade), fuel filter/water separator, fuel pump (Mallory mechanical). The carb was rebuilt a month ago. I ran it this past weekend after the the new fuel pump was installed - and she ran great - but the longer I ran it - the more problems I had - I thought it might be bad fuel - I was down to about 1/4 tank - so I let it almost run out of gas by letting it idle at the dock for 1/2 hour or so - then refilled the tank - and took off - got about 200 yards and she died - I pulled the line off the carb and no gas! Can't believe the new pump has failed already. I'm thinking vapor lock - experts please weigh in here. I am considering the following: 1) Install an electrical fuel pump - any recommendations? 2) Relocate the new pump and fuel filter/water separator to the rear of the boat close the gas tank 3) run an insulated fuel line from the pump to the carb - any recommendations on an insulated fuel line? 4) last resort install a/c in the engine compartment - not really but have thought about a fan. Please let me know what you think. Thanks in advance for any and all input!! Glen |
Replies:
Posted By: GottaSki
Date Posted: September-05-2008 at 1:12am
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Doubt it. Not enough heat.
You likely have a restriction in the fuel pickup/lines and/or clogged vent. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Gleno4224
Date Posted: September-05-2008 at 1:28am
| I will say - I pulled the line off the out side of the fuel filter - and gas poured - I also sucked on the line going into the carb - got fumes at first - then gas. |
Posted By: 8122pbrainard
Date Posted: September-05-2008 at 8:36am
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Glen, Welcome to the place that I feel will help you!!
Before you go and redesign the fuel system with a electric pump, find the problem. There are thousands of marine engines out there without them! I agree with Tom (gottaski) on the vapor lock. Real tough to do with a marine engine compartment running low temps compaired to a car. I'd get a pressure gauge T'd into the fuel line to the carb and see if it tells you something. We need pictures! ------------- /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: 79nautique
Date Posted: September-05-2008 at 10:45am
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have you replaced the fuel and water separator's filter lately?
vapor lock no not going to happen. have you checked the check valve and the tank vent? are the clean? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: Gleno4224
Date Posted: September-05-2008 at 10:06pm
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Thanks for the replies, I really appreciate it.
GottaSki - I'll double check the lines and be sure all is clear. 8122 - Thank You - I've already learned an enormous about just reading posts! I've got a gauge I'll T into the fuel line and check pressure. 79 - I have replaced the old fuel filter/assembly with a new fuel filter water separator. The symptoms haven't changed - so I do think the new filter is causing any issues. I need some education on the fuel tank - I have a florida marine tank - I've taken off the fittings - there's a welded on male threaded connection on the top of the tank - I assume the pickup line is inside this connection - but not sure how to get to it or remove it. I think the tank vent is ok - when filling the tank and it gets full - I do get gas out that vent line - I'll pull the line off off to be sure it's clear. I do not know where the check valve is - please advise - I've read about anti-siphon valves - but there's not one on my system that I've been able to find. I have not pulled the fuel gauge assembly out of the tank (yet). I'll do some more troubleshooting this weekend. Thanks again! Glen |
Posted By: 8122pbrainard
Date Posted: September-06-2008 at 12:00pm
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Glen, The anti-siphon is the check valve. It's usually on the top of the tank's fuel line connection. It's a small ball check that prevents gas going back to the tank. You should have one in there but I don't think that's your problem. It sure sounds like you are sucking air someplace! ------------- /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: Gleno4224
Date Posted: September-06-2008 at 7:18pm
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8122 - Thanks for the explanation on the check valve - I am 99 percent sure I don't have one. Could that be my problem? After running for a while - then shutting down - could fuel be siphoned back into the tank? I wonder if it's as simple as that?
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Posted By: 8122pbrainard
Date Posted: September-06-2008 at 7:59pm
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Glen, I re read the description of the problem several times and yes it does sound like you get air in the fuel line. The anti siphon to my knowledge is there so the fuel doesn't drain back to the tank when the engine isn't running. Could be it!! ------------- /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: 8122pbrainard
Date Posted: September-06-2008 at 8:03pm
http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/277159/377%20710/0/anti%20siphon%20valve/Primary%20Search/mode%20matchallpartial/0/0?N=377%20710&Ne=0&Ntt=anti%20siphon%20valve&Ntk=Primary%20Search&Ntx=mode%20matchallpartial&Nao=0&Ns=0&keyword=anti%20siphon%20valve&isLTokenURL=true&storeNum=6&subdeptNum=78&classNum=90 - anti siphon
 ------------- /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: The Dude
Date Posted: September-07-2008 at 1:21am
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Is that your anti siphon our are you just happy to see me? ------------- Mullet Free since 93 http://www.correctcraftfan.com/diaries/details.asp?ID=717&sort=&pagenum=1&yrstart=1991&yrend=1995 - 95 Sport |
Posted By: eric lavine
Date Posted: September-07-2008 at 12:16pm
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Pete, or if your line falls off or is cut, the gas wont(siphon) drain into the bildge ------------- "the things you own will start to own you" |
Posted By: 8122pbrainard
Date Posted: September-07-2008 at 1:25pm
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Eric, Yes, I just found out the true purpose of the anti siphon valve. The good Boat Dr. just called me!!
Glen, since I have been corrected, I'd go back to my original suggestion and see what the gauge T'd into the line tells you. The valve is there to prevent gas from being siphoned into the bilge in case the rubber line to the fuel pump fails. It's very true that you can learn something every day of your life and still die stupid!!! ------------- /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: eric lavine
Date Posted: September-07-2008 at 1:34pm
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you wern't wrong, its dual purpose you forgot to mention it ------------- "the things you own will start to own you" |
Posted By: Gleno4224
Date Posted: September-07-2008 at 9:43pm
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LOL - no problem 8122! I know I learn something everyday - I really appreciate everyone's input.
Thanks for clarification on the anti-siphon - I didn't have one - so I have added one at the tank. Hopefully that will correct my sporadic missing problem - and be safer if a fuel line break does occur. I have re-worked all connections from the tank to the carb. Still no gas - so I pulled the new fuel pump and suspect it's busted - the lever that drives the pump has a whole lot more play in it than it did originally - and more than the old pump - meaning the lever will push all the way down to the housing, whereas before - it would only move maybe 1/2 way towards the housing, if that. Not sure if I installed it incorrectly, or if it was suspect from the start - strange that it ran great for a few hours before it broke. Now that I'm back to the pump, would you recommend sticking with the mechanical, or converting to an electrical? I'm leaning towards mechanical since the original last 30 years. As always - thanks for the info! Glen |
Posted By: 8122pbrainard
Date Posted: September-08-2008 at 8:13am
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Glen, I'm wondering if you got the actuator arm on the cam lobe when you put in the mechanical. If it was off to the side it may be what busted it - but then it probably wouldn't have even worked! May be just a bad pump. I'd get a new one on and give it a try. Mechanicals did and continue to do the job. ------------- /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: Gleno4224
Date Posted: September-08-2008 at 10:09pm
| Thanks 8122 - I'm ordering one tonight - should have it in time for this weekend and another test. |