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Vapor lock or what?

A

ALF1

Member
Hi Boaters,
This is my first time here and I have a problem that's driving me crazy. My 1997 SeaRay Deck Boat with a 5.7LX EFI with a BRAVOIII has a fuel cooler with Throttle Body fuel injection with the fuel return line travels back to the water seperator.
I have been using regular car gas with less then 10% Ethanol. Ever since I had a new remanufactured MercCruiser engine installed in 2007 and new fuel pump in 2008 I have been experiencing a vapor lock. When I first start the boat it starts and runs fine but when I stop after a run for 1 to 2 hours then I can't start the engine until is fully cools down ,about 3 to 4 hours, then it starts right up.
I tried every thing possible to keep the engine compartment as cool as possible by opoening the engine cover and running blower and running at idle for a few minutes before I shut down.
I have gotten different answers for several mechanics. What do you boaters say before I start to use fuel with no Ethanol to see if this is the fix.
 
EFI can't "vapor lock".
Take off the flame arrestor. Have someone crank the (hot) engine while you look in the throat of the TBI unit. You should see fuel coming out of the injectors. Yes? no spark. No? no fuel. So, troubleshooting will need that information before we can go any further.
 
Are you letting it idle 2-3 minutes before shutting it down????????

Vapor lock, vapor lock sheech people who don't know always say that usually it's something else, i would say 98% of the time.

Your motor showing any codes ?
 
A while back someone else posted a similar issue. If i remeber correctly there is a merc service bulitten for this issue. Maybe one of the more EFI savy contributors here will respond.... Boattech or one of the others. ..
 
Thanks for your input. Why can't the fuel before it gets to the fuel pump get to hot and cause the vapor in the fuel line? However, I will check today after I run for awhile and see if I get fuel when I try to start up after it sits for awhile. I do let it idle and I open up the hatch when I stop, engine in shade of cover.
 
take a spare plug if it happens again pull a plug wire install the spare plug hold it to the block and crank see if it has spark no spark then post back we will go from there.
 
EFI is not supposed to Vaopr lock, but what happens after extended period of use, is with a quick shut down the hot water in the hose from the t-stat to the cool fuel housing back flows hot water into the cooler and causes the fuel to boil. Mercruiser will not admit a problem but there is a one way check valve that is easily installed merc/quicksilver # 21-862271A 1 they are about $100.00 We install about 5 of these a year
 
Ok came back from my trip boating today. It did the same thing. Started right away and ran like a champ for the first 2 hours at all speeds. After running for about 2 hours I stopped for lunch and let the engine run at idle for 10 minutes before I turned it off. I had the engine compartment open before I stopped and left it open in the shade for about 1:15 hours. When I tried to start it I removed the flame arrester so I could see if I was getting fuel in the throttle body from the 2 nozzles. I did get a spray ( I think it looked like a even good spray from both nozzles) but it had a sloggest start. The first time no start but it did spray fuel. The second time it spuddered and I slipped it in nutural to advance the throttle. It finallystopped spuddering and then started to run fine.
I took it out of the water and took it home to wash the boat and fluse the engine. About and 1 1/2hours from when I left the dock to being finished with cleaning the boat I started the engine and it started first time.
I just had new spark plugs put in last week and the boat starts right up when it's cold.If it's not the vapor lock could it be a coil or something else electrical when gets hot would do this?
 
Do not start looking in the wrong place..... With efi it is best to let those with appropriate test tools to troubleshoot. Advice from the internet is just that..... Advice.
 
I understand but everytime I go to the expert the last thing he wants to do is find the problem. All he wants to do is replace parts. Every time I ask if he would but the computer to the unit he says it won't help. I now have a new service guy with a different organization. all of the advice I get is at least a start for a dummy like me to use.
 
Hey ALF1,I go through frustrating times like you, I wouldn't use the word dummy but educating ourselves with the help of some real experienced people on this forum.
Sometimes the easiest problems end up not being that. They'll help you through it like they help me.
 
Frustrating times is when you can't get your wife to go on a boat trip with you anymore when she doesn't know if the boat will start or not.We got great boating here in Florida and we usually invite friends to join us in the fun and beauty of Florida waterways. If I can't fix this problem the boat will go up for sale. I'm getting to old and cranky to deal with this much longer. The only thing that keep me going is knowing that there is someone out there that will give me the right direction to fix this mechanical problem. If we can send people to the moon we should be able to fix a boat engine.
 
Was this the service bulletin you where thinking of Kghost?
http://www.boatfix.com/merc/bullet/99/99_07.PDF

kghost said:
A while back someone else posted a similar issue. If i remeber correctly there is a merc service bulitten for this issue. Maybe one of the more EFI savy contributors here will respond.... Boattech or one of the others. ..
Click to expand...

greg hessler said:
EFI is not supposed to Vaopr lock, but what happens after extended period of use, is with a quick shut down the hot water in the hose from the t-stat to the cool fuel housing back flows hot water into the cooler and causes the fuel to boil. Mercruiser will not admit a problem but there is a one way check valve that is easily installed merc/quicksilver # 21-862271A 1 they are about $100.00 We install about 5 of these a year
Click to expand...
Greg, welcome to marineengine.com, Thanks for helping out, Your post are very helpful and provide a good view of what to look for from different perspectives from your marine experience you hold.:)

I have yet to do one of these kit's Myself. Do they come with directions on how to install the valve? Just so the O.P is aware of the fact of yes or no.;):) Thanks again.
 
EFI can vapour lock but I doubt this is the issue here since you've tried running with the hatch open. I suspect this would keep the compartment temperature cool enough to prevent temperature induced vapour lock. As should be noted in the bulletin however, if I remember correctly, pulling too much vacuum (2 in max) will cause the same issue. Make sure you're running the right size diameter fuel line since the repower and that there are no restrictions or too many tight bends. Follow the suggestions noted in the Merc service bulletin above, all good info they put together a while back. If you have a fuel filter on the starb side mounted to the engine down low, it should have come with a plastic cover. Most people take it off and throw it out. It's purpose is a heat shield meant to keep heat away from the filter to help minimize vapor lock. I suspect this application does not have a VST unit?

I would check simple things first; when you can't start, pull a plug wire as noted above and ensure you have spark so we iliminate ignition as a possibility. After you shut the engine off, pull the flame arrester and see if the injectors are leaking fuel. Check your IAC to ensure it's working after it warms up or hold the throttle plate open a bit when restarting and see if that works. Would help to know if there are any codes recoded.
 
I feel a little bit better today. My frustrations from yesterday put me down but I'm back up today and will fix the problem.
I will check spark but the problem only happens after running and letting the engine sit for 1 1/2 hours.
I have been trying to follow the Service Bulletin that was issued Nov 2001 for the last year. Since I'm now down to less then a quarter of a tank of gas I will fill the tank with fuel that contains no alcohol (Marine fuel) and see what happens. The check valve kit sound interesting and I guess I didn't see that in the service bulletin when I read it. This sounds like a simple fix. I think I will do all 3 items on the Service Bulletin if i see no change with the marine fuel.
Any idea why A hood is mounted over the flame arrester? Is it just for looks or does it have a function. It seems to me that this plactic cover just restricts air flow around the flame arrestor. As long as the engine hatch is down and/or there is no possiblity for water to enter the throttle housing through the flame arrester I'm removing it and see if that helps also.
 
With a efi motor as yours I would not be suspecting the alcohol in the fuel as an issue........

the plastic cover is also not your issue so leave it alone.........If the flame arrestor is clogged with crap then wipe it down with a clean rag and that is all you need to do.

EFI is a great thing until issues arrise.........this is when a knowlegable tech with good EFI trouble shooting experience is needed. I do not have it so I can not give an answer for your issue. All I can say is be patient and do as others suggest.....
 
Yes the instructions are infallable. It takes about 45 minutes to install all you need is a screw driver and a hose cutter the clamps and instructions are to the letter. It seems most of the boats we have had this issue with are sea Ray 200 thru 230 models mid ninety year models
greg
 
Thanks will try it. I saw the part at the SeaRay dealer today.and it is a simple thing to install. Without the instruction I would quess it would be put on the hose after the water flow is out of the engine somewhere. My question is, however,will that restrict any flow of water through the system? The valve probably has a spring holding the plug to the valve body and the water pressure opens it and when the engine is running and it is closed when the engine is off.How long will the spring hold up with salt water use. I do flush the engine after every run but just concerned about flow restriction and if that would increase the temperature in the engine.
 
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It goes in the hose from the t-stat housing to the hose on the cool fuel tube in the front of the engine There is a 6" section of the current hose you cut out and install in that spot Definitely need to make sure the arrow (flow) is going toward the t-stat housing
Salt water don't know? We are in the mountains of east TN We have never had an issue with flow restriction, and I started installing these valves about 10 years ago
greg
 
Thanks, I know now where it goes. The water from the raw water pump goes through the Fuel Cooler before it goes to the engine. Now I understand what it will do. When you stop the engine then the valve closes and does not allow any water to drop down the hose to the fuel cooler.
 
Thanks, I'm going to do what you said and also going to put a fuel pumps kit in per MerCruiser service bulletin No. 99.7 dated Nov. 2001. My service guy has a boat just like mine with the same engine and he put this system in several years ago and said it is working 100% for him.He uses regular fuel so if this works that will save me money on fuel alone that would break me even in 6 months for the added cost of the fuel pump. It's only money so I hope it works and makes boating fun again.
 
Did both the check valve and the buster fuel pump. Took it out in 98 degree weatherhere in Florida on Saturday ran it for 1 1/2 hours to get the engine very hot. Turned it off for 1 hour and it started right up. I think the problem is now solved.
 
ALF1 said:
Did both the check valve and the buster fuel pump. Took it out in 98 degree weatherhere in Florida on Saturday ran it for 1 1/2 hours to get the engine very hot. Turned it off for 1 hour and it started right up. I think the problem is now solved.
Click to expand...
:cool:
 
What I have done to help stop this, was put in 2 more blower motors in.Only difference thing, I would draw fresh air in to motor...then leave other blower on to remove the air...I found it works great, on engines that are vapor locking....You get you heights heat soak when engine is off....
This works great on big blocks that need lots of air to run.... I have no doubt you are vapor locking....


Steve:eek::)
 
greg hessler said:
EFI is not supposed to Vaopr lock, but what happens after extended period of use, is with a quick shut down the hot water in the hose from the t-stat to the cool fuel housing back flows hot water into the cooler and causes the fuel to boil. Mercruiser will not admit a problem but there is a one way check valve that is easily installed merc/quicksilver # 21-862271A 1 they are about $100.00 We install about 5 of these a year
Click to expand...



Greg, would you happen to know if this vapour lock problem would effect my Mercruiser 3.0 litre/LX Serial No. 0K195035 as we are experiencing the same symptoms. It is the carburetor version not sure of the year.

Thanks Mike from the UK
 
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