mercury 240 efi question

[speedster96]

Just purchased SD jet boat with the 240hp EFI. My question is why does the manual say to "never start the engine (even momentarily)without water circulating". How could a couple of seconds hurt? there is no water pump like an outboard. I really would like to just turn over key and here it fire before leaving for the dock without having to open hatch, remove engine cover, and attaching hose.
thanks

[John Kubiak]

As the 240 EFI is an outboard powerhead, the manual was originally for an outboard. You will not harm the cooling system, but it is possible to do some type of damage to the rubber components in the exhaust system if, for example the engine backfires, and this is reduced considerably by having cooling water supplied to the engine.

[ November 24, 2002, 08:50 PM: Message edited by: John Kubiak ]

[Marky]

John,
what exact rubber components are you talking about?I've never heqard this explanation before and have been wrking on Mercury outboards for quite a while as a certified tech.I love learning new things,so I want to be clear that I am not challenging your explanation,but merely seek more knowledge on this subject.I know that with an outboard you would ruin the rubber impeller in a matter of seconds without a water supply.
Thank you,
Marky

[mattgross]

im not sure about this but is if the cooling system is open like most 2 strokes, then it take a couple secconds for water to flow no matter what and if it was started on land ind run for 5 sec it wouild be just like in the water for the first secconds of start up

[Marky]

Matt,
relax dude.I meant like 30-50 seconds,okay?

[mattgross]

?relax dude? if you read the guys first comment all he want to do is start it for a couple seconds, and i am thinking that wouldn't hurt, it had nothing to do with your post, and i was just stating my opinion, and even if it was inresponse to your post, i don't see anything to say that i was agitated or being mean, so i don't understand you comment

[Marky]

Matt,
it just seems you are always at the ready to correct someone.I didn't try to say you were being mean or agitated.So,again,relax.No one is freaking out on you,Okay?It sounded as though you were correcting me for saying the impeller would be destroyed by not being supplied with water,which it would.In an outboard ,the lower unit is under water and the impeller is therefore exposed to water immediately upon start up.It takes a while for the water to exit the tell-tale because it has to work it's way up the cooling system, from the impeller housing.

[mattgross]

i didn't even read that part about the impeller till now, i was not refering to your post in anyway, i was only talking about the motor, and anyway i said i was not sure about the cooling system, and anyway your the one correcting me, because i was not sure, and we are not even talking about the same parts

[John Kubiak]

Marky,
As stated before. the outboard powerhead is installed as an inboard engine in this application. All of the exhust system is connected by rubber hoses in a manner similar to a stern drive for a larger boat. these are the rubber parts I was referring to.

[Havasu Lou]

Re: mercury 240 efi question

Hello All !

I own a 2000 Sea-Doo Islandia (Jet), with the Mercury V6 efi 240 hp.(stock)
I interested in aftermarket performance.

Any suggestions for performance mods ? re: impeller, engine mods, etc ??

It's only used in freshwater. It seats 12, so it kind of strains, when fully loaded.

Also, is the impeller a do-it-yourself mod ?

Any help or suggestions would be appreciated.

Thanks, Lou