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Help! :( Out of ideas.


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So my good friend bought a 1995 Malibu Sunsetter a few years back. It ran great all that summer. We had it winterized and then dewinterized and we started seeing problems. Here's a brief description.

The boat starts off the day running pretty well... We get some drinks, head out on the lake, no problems. After running for a while (and sometimes stopping to hang out and drink on the lake) we'll start it back up and it begins to stall periodically. It just kills all together as though the fuel supply was cut off somehow. This happens with increasing frequency untill the boat wont stay running at all and we have to get towed in.

He's actually taken it to the dealership and they couldnt find anything wrong. It's a 454 so there's no carb to worry about, etc... the filters have been replaced. there's no water in the gas.. to be honest we're running out of ideas. Our next guess is to replace the plugs and hope that helps.

Any help/advice would be greatly appreciated.

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Maybe vapor lock situation. Search the site for vapor lock...there is a ton of disuccion about this.

If it is vapor lock due to heating of the fuel pump this fixes are easy. Run the blower while you are stopped to circulate air through the engine box, or dampen (not dripping wet) a towel with cold water the place it against the fuel pump to cool it down. Should start right up after that.

Edited by BuFootin
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I believe your engine is TBI. (throttle body injected) You probably have metal fuel lines that run down from the TBI to the fuel pump. These lines get heat soaked along with the fuel pump and TBI and turn the liquid gas to vapor. Your fuel pump pushes liquid not gaseous vapor, so no fuel moves up from pump to TBI. If your boat starts and runs with no problems at the start of your boating day, but incurs this starting problem when you sit/hang out after running the boat for awhile then all you need to do is when you sit/hangout leave your engine hatch open. I have had similar problems on both my boats one MPI(fuel injected) and one mechanical/carb. It has never occurred on either boat when I leave the hatch open after running and then sitting. If you forget to leave hatch open then you have to resort to cooling fuel pump,lines,TBI and fuel rails(MPI) with cool rag/towel and allow some time for the vapors to return to there liquid state. The easiest way to show you how this happens is to take an old style vented plastic gas can with some gas in it and leave it in the sun for a little while. You will see it expand dramatically. open the vent and see how much vapor comes out. Our boats have the same thing happen to them. The engine block heats up the fuel wherever it can and the vapors build up and get trapped in places that create air pockets (fuel pumps, lines, rails and throttle bodies.) Until this vapor is released(very dangerous and explosive) or is cooled and returned to its liquid state it acts as a block/impediment for liquid fuel to travel its normal path. This is why you experience fuel delivery problems. Remember this solution only works if the problem does not occur at the start of the boating day and when there is no problems starting the boat after short periods(few mins.) of the engine turned off. As long as your problem only exists when sitting for awhile after running the engine then leaving the hatch open should work, plus its an easy way to find out if heat soak (vapor lock) is your problem and it doesn't cost anything just your memory to leave the hatch open. Keep in mind while running the blower helps it can't efficiently remove as much heat as leaving the hatch open, and you don't have to worry about running the battery down while your sitting. One last note if you don't have a bimini and an open hatch exposes the engine to direct sunlight the benefits might be muted a little, but its still better to leave the hatch open then closed.

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:plus1: On leaving the engine hatch open while sitting!

I had the same issues and when it's beach/raft up time I fold a towel over a few times and put it between the hatch and the floor and I run the blower for a bit when I first stop. It's worked like a charm for 2 yrs now...

Good luck!

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Last time this happend we ran the blower for like 30 minutes - shouldnt this have helped if that was the issue?

Blowers are meant to remove gas vapors. They are usually mounted on the transom or back of the engine and though they will usually remove enough gas vapors to avoid an explosion they are not meant to cool an engine. They just aren't big enough or efficient enough to do that.

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Blowers are meant to remove gas vapors. They are usually mounted on the transom or back of the engine and though they will usually remove enough gas vapors to avoid an explosion they are not meant to cool an engine. They just aren't big enough or efficient enough to do that.

Exactly, and they pull from down by the bilge. Heat rises, open the hatches and let it go!!

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Sounds like a weak fuel pump to me. I would check fuel pressure while you are having problems. Hopefully you have a fitting on your fuel rail that will make it easy but I don't know if they were using those in 95. You can try tapping on the pump with something metalic to see if that helps. There are only a few things that works with but fuel pumps and starters are a couple of them :)

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Sounds like a weak fuel pump to me. I would check fuel pressure while you are having problems. Hopefully you have a fitting on your fuel rail that will make it easy but I don't know if they were using those in 95. You can try tapping on the pump with something metalic to see if that helps. There are only a few things that works with but fuel pumps and starters are a couple of them :)

When I had this problem, my first thought (guess) was fuel pump as well, so I changed it. It didn't solve the problem...

While blowers are meant to remove fuel vapors they will also increase air flow through the engine compartment, thereby decreasing overall engine compartment temperature which stands to decrease the chances of vapor lock. The solution I (and others) are suggesting is FREE! Give it a try before buying parts or paying a mechanic to diagnose the problem for you...

Just my .02 fwiw...

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I had a similiar issue a several years ago in our 86 ski supreme with a carburated 351. I threw a lot of parts at it including a new carb, fuel pump, and fuel lines. In the end, there was a check valve in the top of the fuel tank that had a weak spring, and would occasionally suck closed on me, a new fitting fixed the problem. Then a couple years later we had similiar problems again that I could have sworn was fuel related. That time it was a module that was part of a points conversion kit that would heat up and die on me. I put the points back in and everything was back to normal. Just a couple things to look into.

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This is a long shot but check your safety lanyard. Our 2004 Wakesetter would not start one day when we put it in the water. After sitting in the parking lot for awhile we pulled the lanyard off and pressed the button in a little harder with my finger. Fired right up. Since then it has died a few times out on the water but we just jiggle the switch around and it always starts. We are thinking a bad connection or maybe some corrosion inside the switch is the culprit. Going to pull it once we get it home. Ours was an easy fix. Hope yours is too!

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I would lean towards the electrical end based on the limited information. Lanyard kill switch, loose connection, etc. There may be a oil pressure switch that's cutting off the fuel pump too. I haven't worked on that vintage 454 in forever.

Peter

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