Vapor Lock or Coil issue

[BIGALF]

Re: Vapor Lock or Coil issue

What service bulletin Is it a Mercruiser bulletin?

 

[Dshow]

Re: Vapor Lock or Coil issue

FYI - I was (knock on wood) experiencing a vapor lock issue two seasons ago. The main thing I did was to increase ventilation to the engine as well as install the raw water check valve mentioned in the service bulletin. For reference, here are videos of my engine suffering from the issue as well as a good start. You can see there is much better fuel flow on the good start.

Hot restart attempt:


Good start:


The Mercruiser service bulletin I used is titled 'Gasoline Engine Vapor Locking' Revision Nov 2001. No. 99-7

 

[BIGALF]

Re: Vapor Lock or Coil issue

Your hot restart attemp sounds just like my boat. I'm convinced that the vapor lock is the issue and I will do both the raw water check valve and the extra pump in the service bulletin. I will even use marine fuel with no ethonol the next to I need a full up.

 

[RANDE]

Re: Vapor Lock or Coil issue

Before you go through the hassle of installing the check valve, make sure that it will help you.

1. With the engine running at normal temp, hold the raw water hose that runs into the "Cool Fuel" module. This should be located on the port side of the engine, below the PS Pump. Obviously, be careful doing this. Or, if you have a temp gun, shoot a reading of this hose.

2. After running the boat, shut it off, and start taking temp readings of the bottom end of that water hose. If you have hot engine water siphoning back into this hose and turning the "Cool Fuel Module" into the "Fuel Boiler Module", this hose will become noticeably warmer, almost to the point where it's too hot to touch.

If this is the case, it is very likely that all you will need is the check valve installed. I did mine right after my previous post and haven't had an issue since then. I've even tried to vapor lock it by not idling down, or ventilating the engine compartment.
The Check valve is a very easy install, just make sure you measure out the install location with the hose on, as it is a bit wider and you don't want it interfering with other components.

Good luck!

 

[Dshow]

Re: Vapor Lock or Coil issue

If installing the check valve, make sure you place it where you have access to the water drain on the side of the check valve.

 

[BIGALF]

Re: Vapor Lock or Coil issue

I will definitely try this but 1 question. Will the check valve restrict any flow of water when running? Will I see the temperature gage go up? The valve I saw today at the SeaRay dealer is nothing but a PVC valve with I guess a spring loaded check valve inside. Will the salt water have any effect in the spring loaded valve? (I guess it's spring loaded) I do flush the engine after ever outing.
Thanks for your input. I will try it ASAP.

 

[BIGALF]

Re: Vapor Lock or Coil issue

What type of fuel do you use? Do you use fuel without E10 Ethanol (marine fuel)? I was going to drain my fuel tank and see what happens if I just use fuel with no E10 Ethanol. I rather use regular fuel and just do the valve if that will work.
Any suggestions would help.

 

[RANDE]

Re: Vapor Lock or Coil issue

I haven't noticed any difference in operating temp with the check valve installed - running fresh water only, but I doubt salt would have any immediate impact. If you're flushing every time out it should last just like any other part.

I have no way to get anything other than E10 out here, none of the docks have E0. Been through 2 tanks of 89 Octane E10 over the past 3 weeks with not one single miss, issue, stall hesitation or rough start.

 

[BIGALF]

Re: Vapor Lock or Coil issue

Will do and also will install another fuel pump between the fuel tank and the water seperator that is also suppose to help per the MerCruiser Service Bulletin No.99-7 dated Nov 2001. This pump is a low pressure pump that will feed fuel to the fuel pump in the cool fuel system. I understand all the new boats like mine have 2 pumps.
Again, thanks for steering me in the right direction.

 

[BIGALF]

Re: Vapor Lock or Coil issue

Just to update you all. I did both the check valve and the booster fuel pump. The boat is working great now. I had the boat out in 95 degree temp here in Florida and ran it hard and stopped it for one hour and it started right up with no problem. I recommend this fix to all who have this problem. If you have time and want to save some money try just putting in the check valve first. I was running out of time and patience so I did both at the same time. I'm a happy boater again!!!

 

[ryanr623]

Re: Vapor Lock or Coil issue

Just to update you all. I did both the check valve and the booster fuel pump. The boat is working great now. I had the boat out in 95 degree temp here in Florida and ran it hard and stopped it for one hour and it started right up with no problem. I recommend this fix to all who have this problem. If you have time and want to save some money try just putting in the check valve first. I was running out of time and patience so I did both at the same time. I'm a happy boater again!!!

What is the booster fuel pump?

 

[Dshow]

Re: Vapor Lock or Coil issue

See #29 above or here is a link to the Service Bulletin:
http://www.boatfix.com/merc/Bullet/99/99_07.pdf

 

[hcove7]

Re: Vapor Lock or Coil issue

If installing the check valve, make sure you place it where you have access to the water drain on the side of the check valve.

BIGALF- Did you eventually install the check valve, and if so, did it work? I've had the same problem for the 3rd season.

 

[NHGuy]

Re: Vapor Lock or Coil issue

Hcove, yes he did & it was the solution. It's only a couple of posts back.

To see how little fuel is delivered when the cool fuel system gets too hot, versus a good system look at the 2 videos that link off the pics on the post from Dshow, on 6/5/2011 @9:36AM.
Watch just below the 2 injectors which are supposed to deliver a mist of fuel into the throttle body. In the before video there's hardly any fuel. In the after video it's a cone shaped mist of atomized fuel and the motor starts right off.

 

[spdracr39]

Re: Vapor Lock or Coil issue

I had this same problem and I resolved it for free by opening the engine hatch for about 15 minutes when we stop. No more issues and no add-on parts to fail. It was 105 here Saturday and had no issues. Once the hot air is purged from the compartment you can close it back.