Vapor Lock, Fuel Issue???

I have a 2001 monsoon, fuel injected motor in my Sunsetter. After running the boat for an extended period of time, then sitting for 1 to 2 hours, it will start but continue to stall unless I run it in neutral at higher RPMs for about 15 to 30 seconds. If it does stall, it will start immediately when I turn the key but stall again almost immediately. The engine seems to act like its starved for fuel.

Cold, the boat always starts instantly and there is no problem is I shut it down briefly and restart.

What would be the cause of this? Is it connected with the heat buildup in the engine compartment?

I had almost the exact same problem last weekend.

I was going to change my water separator, I'm thinking it could be water in the gas.

Mine would start but after 30-45 sec it would stall then act like it was starved for Fuel. Getting it to start against took some work but once started it would run great until it sat for 1-2 hours.

It did exactly the same thing every time for 4 straight days.

My thinking was after shutting down the engine compartment would get so hot that the fuel sitting in the delivery system was somehow effected. The engine compartment gets quite hot with no air movement. Aside from the fact its 95 degrees.

On my last trip I ran the blower for 30 min after shutdown and stuck a flip flop under the engine cover to give it a little air. After a few hours it started without hesitation.

I never have had the boat not start cold the instant I flipped the key.

Can anyone help?

Probably vapor locking. The only other thing to maybe consider is that when you engine compartment gets that hot your engine coils may be expanding and not working correctly. That would cause your spark to be off and not fire correctly, which would also give the same symptoms as discribed. We had a car that did this and it was almost impossible to trace.
Just an idea I guess.

Tim, you have the exact same problem that I've had in the past and still do from time to time. Your problem may have the same cause as mine so let me explain what's been happening on mine.
We have the same engine as well. Since V-Drives have remote oil filters there are oil lines that go between the filter and the block. The fuel line, for some reason, runs right along those oil lines. And as we all know, those oil lines get extremely HOT. The fuel in the fuel line does get hot, but it doesn't get hot enough or spend enough time in the line to vapor lock due to it stays moving. It's when you stop for an extended period of time after boarding and running the engine hard. The fuel heats up in the line due to the oil line, vaporizes and hence vapor locks.

If this is your cause as well, try to separate the two lines and put some heat shield between the two. I've separated the two lines on my boat. It's helped, but every once in a while I do get hesitation. I need to separate them more and get a heat shield in between the two. When it happens on my boat I open the hatch and pour water, lake water, on the lines for a few minutes. Then I let it sit for a few more minutes and it solves the problem for that moment.

check to see if fuel system is vented no such thing as vapor lock also check to see if fuel is returning to tank

Not true Shaun. I've had it happen.

Vapor most certainly exists!

Do a simple google search on
boat engine vapor lock

This is one example form Brunswick

On a hot day after I run the engine for a while then shut down, the engine won't restart or it starts and idles fine, but when the throttle is advanced the engine bogs down or quits running and will not restart. Why?
It sounds like your engine may be vapor locking. One factor that contributes to vapor lock is fuel. Fuels produced for use during the winter and early spring months around the United States are designed to vaporize at a lower temperature. This lower vaporization point can cause the fuel in the boat supply lines and engine fuel system to vaporize prior to being used. Another contributing factor to vapor lock is a restriction in airflow into the engine compartment. Make sure that lifejackets, fluid containers or other equipment have not restricted the airflow. Other items that will help to reduce vapor lock are:

Letting the engine idle for 3-5 minutes before shutting it off.
Opening the engine cover to let the hot air escape. Note: Always reinstall the engine cover before starting the engine.
Operating the bilge blower to remove the hot air.

i meant vapor lock on injected motor should never happen there are always other issues cooling system fuel pump water in filter bad gas ect regoogle it

I really don't need to regoogle I understand what it is what causes it and what can make it worse.
Indmar Mercuiser and Pcm and all the other have tried lots of "solutions" Pcm with there fuel cell. Indmar with the in the tank fuel pump and Mercuiser with there cool fuel system

change your fuel filter first. I thought for sure I had vapor lock. I changed the fuel filter and it fixed the problem immediately

in my '02 i had some vapor luck type problems in '03, took it to the dealer and they replaced some parts of the fuel system with some updated parts, not a single issue since.

Vapor Lock is certainly possible. Supra has even started putting two fuel pumps on their boats to fix it because their fuel lines run right next to the block and after you run hard and stop, the fuel vaporizes. We've even got video of it happening on a pressure gauge and bleed off line my friend installed on his 21V to show the dealer.

I also posted on Malibucrew.com and did a search. The problem is very well known.

I ran the blower and cracked the engine cover and eliminated the problem my last time out, but this was one time. I'll have to see if it continues to work. I am also going to examine the routing and sheilding of the fuel system.

My belief is that the increase in heat, after shutdown, within the engine compartment is creating a fuel delivery problem. The engine is very well insulated for sound so without forward movement and airflow it gets hot.

In respect to my filters, they are new and clean. If they were not I would expect the problem at higher RPMs not startup.