# Vapor Lock?



## Choctaw Mike (Sep 24, 2009)

I had a bad weekend to say the least. I picked the boat up from the mechanic on Friday. I blew a trailer bearing on the way home and luckily i limped it to the dock and got the boat in the water. 

I had the following done to it; New spark plugs, adjusted timing, new OIS sensor, adjusted steering linkage, new lube for lower unit, replaced fuel filter. 

Mother's Day - The boat cranked great as usual when it is cold. I ran it for roughly 2 hours pretty hard (from the mid-bay through the destin pass, caught bait with the engine running then trolled for an hour). I came back in and parked the boat at crab island. We were there for about an hour and when i went to leave, the boat wouldnt crank. Long story short, i pulled the fuel bulb and made sure that was working and there was fuel on both side of the bulb. I went back to Destin this morning, boat cranked awesome on the first try and i was able to take it to the dock. 

Im reading up on vapor lock, has anyone had any experience with this on an outboard engine? Do I have a fuel problem? Air problem? Vent problem? Fuel regulator? Im at a loss, so is my mechanic.


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## feelin' wright (Oct 7, 2007)

Might want to look at the fitting to the OB. I had that happen a couple times and come to find out that the O ring had a pin hole and some days it would do nothing but suck air.


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## TheCaptKen (Mar 14, 2011)

Howz about telling us what engine you have? Might make things easier if we know what system you have.


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## Sequoiha (Sep 28, 2007)

OIS, check the connector at the ois sensor, I have had issues with replacement sensors. Also ask your mechanic if the sensor is oem or aftermarket


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## woody (Oct 17, 2007)

I'll just guess that you have last years fuel in it & probably a winter blend. That crap will act just like you stated. Mix fresh fuel into it & burn it up. As you add newer fuel & the ratio improves your trouble will go away..............


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## Aquahollic (Sep 24, 2009)

This might sound like a dumb question but was the boat in Neutral? I had a scare like that also only to find out that I had bumped the throttle in gear.


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## flappininthebreeze (Jul 13, 2009)

I have this happen on my Yamaha 150's, when they have been run and shut off hot, or when they have been sitting in the sun, after running. The engine turns over, but won't fire off and keep running. The only way out I've found is to cover the cowling with a wet towel, soak it a couple times to cool the engine off, pump the bulb and try again. Most times that will do it, but sometimes I have to pump again. Vapor lock from the heat is the only thing I can figure, since it doesn't happen when the weather cools. Other thoughts?


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## Choctaw Mike (Sep 24, 2009)

Its a 1998 150hp Evinrude Ocean Pro. It's not bad gas, yes I have it in neutral, and I dont think its the OIS Sensor. 

I ran it Monday night to go flounder gigging. I stayed in the area and was very aware of what I was doing so I could further diagnose the problem. 

I ran to the spot, moved around a few times and sure enough, I shut the engine off and it would not start back up. So we fished for about 1.5 - 2 hours and the engine cranked at the end of the night!! It typically takes much longer (overnight) for the engine to crank but im thinking since it was the night time, it was quicker. 

How do you fix vapor lock? I hate to bring it to another mechanic with an open tab to start messing with it for no reason.


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## CurDog (Nov 14, 2010)

I had a Evinrude to do me that way once before. It'd run when cold, and it'd run when it was hot, even run in idle. But turn it off, and you might as well fish for 2-3hrs, before it'd start again. I couldn't figure it out, so I called my mechanic, told him the symptoms and he said it was a blown head gasket. Oh yeah sure, I told him. I already knew it wouldn't start at all if that were true. Figured I needed another mechanic. So I finally gave in, pulled the head, had it shaved a touch, replaced the head gasket, and I've never had another problem with it. So, do a pressure test on the cylinders, maybe this is the same problem you have?


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## TheCaptKen (Mar 14, 2011)

If the locking tab is snapped into place on the optics, then the connection should not be a problem. If you have a upper seal going bad, it will leak an oily mixture and will block the signal getting to the optics. This can be cleaned with windex easy but will not solve the problem. But then it would not have started up the following day. Optic sensors are matched to the CDI and you have to make certain the one you are installing is for the CDI on your engine. If not, then you change both the CDI and the OIS. 
Vapor lock is a thing of the past and just used when someone doesn't know the answer. There is no way the fuel lines can get hot enough to vaporize the fuel inside without causing other damage to the engine. This was due to old car engines with steel/metal lines that ran to close to the engine and would get so hot the fuel turned into vapor before getting to the carb. The old trick was to clip several wooden clothes pins to the line and this would prevent vapor lock. Mechanics that have come into being in the last 20 or so years may have heard of vapor lock but has never seen it.


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## duckgrinder (Jul 14, 2009)

Would a over heated coil pack do this? It cranks just no fire right?


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## TheCaptKen (Mar 14, 2011)

There is three coil packs. If none is firing, probably not the coils. You would need to use a peak reading a/c voltmeter go check stator output. But first, be sure your kill lanyard is clipped in fully


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## kanaka (Oct 3, 2007)

Was primer bulb firm?? Check/tighten any clamps on fuel line, sounds like its sucking some air in. And if this was a tune up, I'd be asking the mech some questions.


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## sig226 (Feb 7, 2011)

i had a problem with alchol fuel back a few years back, no one could figure it out i finally read that they were having a big problem with alchol fuel percolating, shut off car when hot , could hear gas boiling out of carbs, went to regular fuel never did it again. they said in texas there would be line of cars that had just stoped and fueled up with achol fuel, get out on interstate 20 or 30 would stall. took me a yr to figure that out. wouldnt crank for 15 min. achol fuel, devil fuel, boils eaisler than regular fuel. i would thing its perlotating(boiling) instead of vapor lock, retired county shop foreman, diesel mech, not a boat mech 40yrs. empty your tank and try a tank of all regular fuel, bet itll stop, read abot it in time mag. ford hadnt even figured it out. drove me crazy, built carb and all, just the fuel


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## Choctaw Mike (Sep 24, 2009)

The primer bulb was not firm. And no matter how much I pumped it, it wasnt getting firm. However this last time I disconnected the bulb and made sure it worked. When I hooked it back up the bulb was hard.


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