Idle Rpm on '87 Mariner 150

[jimmy@wm]

I can't seem to get the idle rpm's on this motor down below around 1300 with muffs.I've checked and set the timing acording to the merc, mariner manual as well as sync on carbs.Is it possible that it has been rejetted or is this normal running on muffs. I'm reworking the trailer now so I cant get it to the water to try it out. I have just finished replacing the water pump complete kit as well as stator and rectifier and fixed broke wire on trigger. Also on muffs the motor runs a at the kine in the gage before the one at hot, water temp is only 138 deg. Any advice will be greatly appreciated. Thanks for your replies in previous post, you guy's have been a great help.<br /><br />Jimmy

 

[dilligafda]

Re: Idle Rpm on '87 Mariner 150

Jimmy, high idle on a hose is normal. You really need the back pressure to set the idle accurately. Once you can get the boat to the water and if you still have a problem with high idle, you need to look for an air leak on the intake side of the engine.<br /><br />Good luck!

 

[jimmy@wm]

Re: Idle Rpm on '87 Mariner 150

Thanks Dilligaf for replying, When you say the intake side I take it you are talking about the carbs and reeds. There is an awfull lot of oil on the air silencer box .Is this normal or does this indicate a faulty set of reeds?<br />Thanks JImmy

 

[KCLOST]

Re: Idle Rpm on '87 Mariner 150

Jimmy, I might have been a little off on idle rpm's while on muffs when I replied to you on a previous post....<br /><br />But your idle is still high... It should be around 800-900rpm max. But I agree with dilligaf, it should be checked in the water before you do anything...<br />Your water temp sounds good. The stats open at 140-145 so you're ok there. Your temp guage measures metal temp so it will be higher than water temp...With higher rpms, higher temps! Especially up until the poppet opens... <br /><br />The air box will get some oil in it, especially when you tilt the engine up after running.. If you want, you can take the air box off and see what is happening while running. But if you read your airbox label they warn against not running the engine over a certain rpm. with it off (so check that out before you hit the throttle, I think it's 3000 which you don't want to do anyway on the muffs).

 

[jimmy@wm]

Re: Idle Rpm on '87 Mariner 150

Thanks KC, You are right about the rpm's on air cover it say's 3000. The merc manual say's not over 2200 on muffs and in gear in water 800 rpm's. I didn't know if it would slow down to that in water from what it run's on muffs. Thanks for the reply.<br /><br />Jimmy

 

[dilligafda]

Re: Idle Rpm on '87 Mariner 150

Yup, what KC said