Mercury 40hp efi won't start hot mystery...can you solve??

[Beaubm01]

My 2003 motor starts right up and runs great. After shutting down and then trying to start an hour later, it starts, runs for a few seconds then begins to idle very rough and then shut down. If I wait a couple of hours it will start and run fine. I have found that if I remove the bottom of the water seperator and then reinstall it will start immediately 100% of the time without waiting for the cool down. Why would that cure the problem? Does that quickly release pressure on the fuel line? Is this vapor lock? Can this be caused by the fuel pump or the injectors? Any help would be appreciated.

ps...Ive replaced my fuel line with the bulb and the filter in the water seperator

Thanks in advance for the help

 

[Faztbullet]

Re: Mercury 40hp efi won't start hot mystery...can you solve??

Sounds like vapor lock as when you remove filter it purges line of pressure...remove anti siphon valve on fuel tank and see if that helps.

 

[Beaubm01]

Re: Mercury 40hp efi won't start hot mystery...can you solve??

Sounds like vapor lock as when you remove filter it purges line of pressure...remove anti siphon valve on fuel tank and see if that helps.

Yes I've tried that. Even had the cap loose and that did work. The last work I did in this motor was to replace the voltage regulator. The Oem one got real hot and fried. There was a service bulletin on these the prior year. given the location of the voltage regulator to the VST, is there any chance when the old voltage regulator fried that it toasted something in the VST?

 

[Faztbullet]

Re: Mercury 40hp efi won't start hot mystery...can you solve??

No...

 

[schematic]

Re: Mercury 40hp efi won't start hot mystery...can you solve??

use fuel with less alcohol content. This will lead to less perculation

 

[Beaubm01]

Re: Mercury 40hp efi won't start hot mystery...can you solve??

use fuel with less alcohol content. This will lead to less perculation

Thanks for the suggestion. I've been using shell gas 89 octane with an additive for 5 years and this just started last year,

 

[Beaubm01]

Re: Mercury 40hp efi won't start hot mystery...can you solve??

use fuel with less alcohol content. This will lead to less perculation

. Thanks. I've noticed that when I remove the filter there is little to no gas in it. Is that normal?

 

[Faztbullet]

Re: Mercury 40hp efi won't start hot mystery...can you solve??

Which filter..motor or boat if equipped?

 

[Beaubm01]

Re: Mercury 40hp efi won't start hot mystery...can you solve??

The water seperator/ filter just b4 the mechanical pump. Its literaly next to the pump. I can see that it fills up with gas when I pump the bulb, but when I have this hot starting problem and unscrew and remove the filter housing cup there is little to no gas in the cup. Remember, when it won't start, I can get it started by removing this filter cup.