This is very weird please read.....

0

04select200

New Member
Jul 21, 2008
51
Lake Cumberland KY
Boat Info
2008 270 SLX
Engines
496 MAG w/ Bravo III
I replaced my IAC valve a month ago on my 2004 Select 200 with a 5.0 MPI, because I was getting an alarm and the motor would stall when it would dropp under 1K RPMs. After I replaced it it ran fine, then suddenly it started with the below issues.

For the last three weekends I have have trouble starting the boat of it runs for a while. It starts great at the beginning of the day, but when I make a long run, and then it sits (while we we are tied up), it is very hard to start. I have to put it in nuetral and pump the throttle to get it to go. It sound like it is backfiring, and then it will stull. After a while of doing this it will finally start and then run fine.

Has anyone ever heard of this happenning. The boat runs fine until it sits for a while, and then once I do get it started it runs fine again. I is almost like it is a fuel pump or something.

Let me know if you have any ideas, I am starting to get pretty frustrated. I want to take it somewhere, but I am afraid they might not be able to get to to act up.
 
I never got an alarm when I had bad IACs in the past..... Take it out and see if it is "free" or not (i.e. can you screw/unscrew the valve?)

Also check the "muffler". It's just a piece of foam-like material to muffle the sucking noise from the IAC inlet.
 
I changed the muffler when I changed the valve. I will check it next weekend, but it acted different when the IAC was the issue. Once I start it back up now it will run fine. Before I fixed the IAC , when I got it started if I went below 1 K RPM's it would imediately stull.
 
Sounds like fuel vapor lock to me based on the facts you presented. There have been several threads on this subject the past few weeks. Just do a search to find them.

Dave
 
Although you may have vapor lock I am not able to continue to help you.

We keep trying to help you but you simply are very difficlut to help.

We asked politely for you to keep your thread together however you continue to start a new thread each time you come here and ignore past, repeated suggestions.

http://clubsearay.com/forum/showthread.php?t=31441
http://clubsearay.com/forum/showthread.php?t=31117

I hope someone else has the patience to help you find the solution to your problems.

Best wishes.
 
I apologize about not posting to the old post I am pretty new to this. I did not know if you posted on a old post someone would see it.

I did clean the flame arrestor, and change the muffler.

I apologize again, I hope you don't hold this against me, I will try to be more careful posting stuff. I was nothing intentional, just learning on these forums.
 
Gotcha. Thank you for replying.


Just so you know, most of us do not go forum to forum looking for new threads. We hit a button to show all posts that are new in the last 24 or 48 hours and look thru those. It does not matter how old your thread is, it’s the time of the most recent post on that thread. Keeping the information together helps us diagnose your issue.


About vapor lock, tell us how you shut your motor down.

I’ll describe two different situations. What one is closer to what you do?

#1) You are going all out, pulling skiers, running fast, right to the end then shut down. The engine goes from full hot to off.

#2) After a long no wake zone and long time with the engine running at low RPM you shut down.
 
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Well, there is the issue.

The hard run gets the intake manifold hot, the fuel in the fuel line directly above the manifold gets vaporized then you have the hard start issue.

If you keep the motor running under a slow or idling use, the fuel continues to flow thru the line so the fuel never gets a change to vaporize.

Here is a poor but easy to understand analogy. You can pass your finger thru the flame of a lighter without burning your finger but you can’t hold your finger in the flame.

This situation is more common in some boats and by some more aggressive captains.

There are design changes including adding expensive heat shielding to the fuel line but my suggestion is to simply allow the engine to cool for 5 minutes minimum before engine shutdown. You can go slow or be stopped, either is fine. You may also want to run the blower at the end, after shutdown for 5 more minutes.

For what it’s worth, I never liked the heat shield solution. It encourages the captain to shut down an engine that is too hot. Even if you can prevent vapor lock with a heat shield you may be doing other damage due to uneven engine cooling.
 
I appreciate the advise, and have been looking at other post, and I do believe that that is the issue. I will take the preventative measures of idleing before shutting down and running the blower more.

I read in a couple other post on on Merc's website that some people are putting in check valve by the fuel cooler. Has anyone done this? How big of a deal is it to do?
 
04select200 said:
I read in a couple other post on on Merc's website that some people are putting in check valve by the fuel cooler. Has anyone done this? How big of a deal is it to do?
Click to expand...

I have the same 5.0 MPI's as your boat except I have two of them.

I have no vaporlock issue but I do not go from hard running to off.
 
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Nope, I just thought I read somewhere that there was a cool fuel system and that you could put a check valve in that would keep the hot water from block going backwards.
 
I agree that is sounds like vapor lock. I had the exact same thing happen yesterday. In fact, it has happened on occasion the past couple of years.

If, after running hard, we shut down for an extended period, it will restart with no issues. The engine/engine compartment has had time to cool off. If we shut down and try to restart after a short period (15-20 mins), we have issues. It seems to occur on hotter days. In those cases, we will open the engine hatch for 10 minutes and the problem is solved.

I run my blowers constantly when the engine is running. I also run them for a few minutes after shut down in hopes of flushing the hot air out of the engine compartment.

I was told that if you cycle the fuel pump - turn key to on position (without starting), you'll hear the beep and then the buzz of the pump - a couple of times, this will force fuel into the lines eliminating the vapor. I did this last year and it worked. Unfortunately, I forgot about this tip yesterday.

Lastly, I totally overlooked the fact that my engine hatch has an access panel on the side. In case of an engine compartment fire, you remove this panel to spray the fire extinguisher (hope no one ever has to use it for that purpose). Since it is located relatively high in the engine compartment, I plan on opening the panel when we shut down to allow hot air out. This will not be done if the bimini enclosure/camper top is up.
 
04select200 said:
Nope, I just thought I read somewhere that there was a cool fuel system and that you could put a check valve in that would keep the hot water from block going backwards.
Click to expand...

We have a fuel cooler in our 5.0L V8 MPI engines.

What happens is when you shut off a very not engine the not water gurgles up thru the thermostat and down the hose that runs to the fuel cooler.

This hot water can be so hot that it vaporizes the fuel inside the fuel cooler.

The people that are adding a check valve are adding this inside the water hose that connects the thermostat housing to the fuel cooler. It’s a big ball about 3 inches around.

This check valve will prevent the vapor lock inside the fuel cooler if that is where it’s happening.

I am going to maintain that if you are using your boat in a manner that you need this check valve then you are not properly letting the engine cool before you shut it down and by adding this check valve you are going to continue this practice and cause other engine damage.

I hope this helps.
 
I appreciate everyones help. It sounds like I just need to keep my blower on and idle more before shutting it off.

It just seems that sometimes it does still happen even when we have been sitting for 1-2 hours before restart.

Thanks again for all of your help.
 
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I have been adding a lot of "Heat" to my fuel, because I thought it was water issue. I am reading a lot that this can cause vapor lock also. Have you heard of that?
 
It happened to me again 3 times this weekend. Each time I would the boat idle for a while and run blower in hopes that is would cool down. One time I had to go through a no wake that takes about 10 minutes.

I would start each time, but then would sputter and stall. It was really hard to get started again, but after that would run fine.
 
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