175 Doesn't idle when hot

[tbsmith]

My 2002 175 sport jet runs fine, but it won't idle when hot (idles fine when cold). This isn't good in a sport jet since there is no neutral and no way to run the engine above idle speed without putting it in "gear".<br /><br /><br />What would be the first thing to try? New plugs are $70 (ouch), but since the boat was only used one year (23 hours) maybe it's something else?<br /><br />Thanks,<br />Tom

 

[2springers26]

Re: 175 Doesn't idle when hot

is it carbed efi?? it makes a diffrence for answers.. need more Info... If carbed here is a air valve on the starboard head that can be faulty.. leaving the motor In a rich condition...if efi that's a whole other issue.. Need to hook It to a ddt & see all the sensor information..

 

[tbsmith]

Re: 175 Doesn't idle when hot

Sorry, it has carburetors. I will check for the air valve. Is it thermostatically operated and I assume it leans out the mixture somehow? How do I test it?<br /><br />I just bought the factory service manual, but it is not very thorough (e.g. - it doesn't describe the manual choke, for instance, although it discusses the EKS). However, it seems to have good info on specifications and major overhaul). I wonder if the Clymer or Seloc versions are any better?<br /><br />Thanks,<br />Tom

 

[tbsmith]

Re: 175 Doesn't idle when hot

I checked I don't see anything that looks like an airvalve on the starboard (or port) head. Several cooling hoses, but that's it. This is a Sport jet, but I would imagine the power units are identical.<br /><br />Thanks for any ideas,<br />Tom

 

[DHPMARINE]

Re: 175 Doesn't idle when hot

tbsmith 1st,I'd research the plugs.2 are listed.BU8H and BUZ8H,both NGK plugs.The footnote for the "Z" plug says RFI,which I assume is if you are using important radio equipment on board.Maybe you can use the less expensive BU8H's. <br /> I think you'll find the after market manuals less informing.A Merc parts manual will help though.It's only about $12.00.<br /> DHP

 

[tbsmith]

Re: 175 Doesn't idle when hot

Thanks, DHP. I will go ahead and try the plugs and see if it helps. <br /><br />Regards,<br />Tom