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Mercruiser re-start problem (Read 657 times)
Mar 27th, 2010 at 11:05pm
khartt   Ex Member

 
Hi all,

    I've got a '96 Mercruiser 7.4 LX MPI (S/N 0K024439) in my '96 25' Commander.  When the engine is cold, it starts and runs great.  After you run the engine for a while and it comes up to temp, if you shut it down and try to restart it immediately, it won't start.  If you wait 5 to 10 minutes, it starts and runs great.  There are no obvious over heating problems.  I head about some possible vapor lock problems with this engine under certain conditions and a fuel cooler system that Mercruiser offered on later model engines.  Any ideas on the problem are appreciated...
 
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Reply #1 - Mar 27th, 2010 at 11:59pm
MercruiserBoatTech   Ex Member

 
Yes it's more then likely a fuel vapor lock.

Make sure your tune up is good, And us 87 octane.

On hotter days you could try lifting the hatch up a little bit to cool the area the best you can.

Or you could try getting a bilge blower and us it as a fan and aim it at the vst tank sucking air from the outside.

Let the engine idle for around 2 minutes before shut down.

Also you have a private massage from me here.

Nice boat by the way, I have a 96 21ft laveycraft 454mag MPI, But so far I have not had vaporlock on mine yet. Wink Smiley Knock on wood. Lips Sealed

Are you in AZ? The boat was sold to someone out there when new new.

 
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Reply #2 - Mar 29th, 2010 at 11:33pm
khartt   Ex Member

 
Thanks for the info MBT.  I checked out the links in the PM you sent.  Great information there, almost too much!.   I'm actually in SoCal,  but, you're right I bought the boat from the original last year and he was living in AZ when he bought it.  I use it exclusively at Lake Havasu.  The original owner mentioned to me that there were some fuel issues with the boat, but he said they were mainly involved with the sender units for the fuel gauges.  He said that the boat sat unused for a couple of years and when he had it serviced to get it ready to sell, the service tech told him that there might be problems with the fuel system due to lack of use.  He "indirectly" told me about the vapor lock issue when he said that the "boat runs better if you remove the center bolster from the rear seat".  I tried that but it didn't seem to relieve the restart problem.  I don't know if you are in AZ, but I have a couple of friends that live in Lake Havasu City and they recommended taking it to Lakeland Marine and having Richie there take a look at it.  I'm heading up there this weekend and I'm going to drop it off there.  By the way, I've 2 friends that have Lavey's and they both absolutely love 'em.  They are great boats.

Sorry for the long post.  If you live in the Lake Havasu area and know anything about Lakeland Marine, I'd appreciate your input.
 
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Reply #3 - Mar 30th, 2010 at 6:19pm
MercruiserBoatTech   Ex Member

 
I live in So-Cal, But I know of Lakeland Marine and I believe I have met Richie before at MerCruiser school.

You will be in good hands with Lakeland Marine, They have been working on boats a long time, And they are known and recommended by Mercruiser to handle a lot of issues for Mercruiser with good success.

Most of their customers are repeat customers, And sometimes that is hard to do when it comes to some boat service shops. Lips Sealed

At least using Lakeland Marine you can be sure that you will be getting the best care for your engine, And more importantly you will be using the recommended tune up parts for your engine so that you can be sure everything is as close to being as perfect as you can get your engine to be, To try your best to cut down on the fuel vapor lock issues.

Also have them check out the oil that is by the mechanical fuel pump/Water pump impeller to see if there is excess fuel mixed in with the oil.

Sometimes there is a little bit of fuel in the oil, But if there is a lot then you will want to install a new mechanical fuel pump, Because in theory if that fuel pump is not work 100% right it could help lead to a fuel vapor lock on your engine, I say that Because there was a short time that MerCruiser did add a 12 Volt power booster fuel pump inline with the main fuel line between the gas tank and engine to help eliminate fuel vapor lock on some engines, So you never know anything is possible. WinkGood luck with it.
 
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