Excalibur 330 '03 backfire

[Fonseca]

Hello again ...
I'm the portuguese Nautiques owner that posted a question related to white smoke and strange engine noise.
The boat is a '03 210 air nautique team edition with a PCM excalibur 330 that have now 610 hours.
Yesterday, after 45 min cruising with 42șC air temperature , i stopped the motor for 2 hours.
When i try to restart, the engine start working irregulary, does not increase rpm when accelarating and backfires like a Harley Davidson. When working, with the idle stabilized, there was a noise coming from the intake manifold like air passing thru a very straight hole (sounds like metal rushing ...).
After 3 or 4 starts the engine runs good, the strange noise have disapeared and i passed 2 hours skiing and wakeboarding without any problems.
The flame arrestor is clean.
The problem apears only when restarting the engine hot and after 30-45 min after shut down. If the engine gets completly cool i have no problems.
Thank you very much for any help.

[Fonseca]

RE: Excalibur 330

Do you think that the quality of the gasoline can be related with the problem?
I use unleaded 95 io ron gasoline from a suplier ... not very credible .... i will change!

[Fonseca]

Anti syphon valve

Hi.
Looking the troubleshooting section of the engine manual, they suggest to verify the anti siphon valve. Does anybody knows where is it located?
Thank you very much for any help

[Fonseca]

RE: Anti syphon valve

I think that the problem has disappeared.
Too much dirty Idle Air Control Valve.
I cleaned it and its running ok.
A special Thank you to Davidf for his essential help.

[Onthewater]

RE: Anti syphon valve

that DavidF sure knows his sh*t.

[Fonseca]

RE: Anti syphon valve

One year later ... and i get the solution!
The fuc*(&%$# problem was a intermitent fail of the high pressure fuel pump.
I just identified the problem because it passed from intermitent to permanent!
Starts and dies, noise from the idle control valve, backfires, etc.
Finally fixed and now runs good.
The only problem now is that I drove the ZR6 !!! what a high regime punch! I like it very much! My excalibur just can do 4900 rpm, but up to 4500 it have not very power.
It's true that i don't need power at high revs, but it's very good the feeling of power that you can get with the ZR6. Does anybody heard about reprograming excalibur ECU's?