Mercruiser 170 dying upon throttling back to idle.

[Jono69]

I have an '86 Wellcraft 190 with a Mercruiser 170 (270hr total, freshly rebuilt by previous owner) and an Alpha 1outdrive. I have had this for about 2 weeks now and have taken it out 3 times. The problem I am having is that when I throttle back to idle from any power setting, usually after a long cruise, the engine seems to bog down and then dies. It appears that it is hydro-locking itself somehow as it will barely turn over, if at all immediately after dying. If I let it sit with the throttle wide open for about 5 minutes, it clears itself out and fires right up. Any thoughts as to what might be causing this to happen and what might be a fix for this? Thanks guys.

 

[Jono69]

Re: Mercruiser 170 dying upon throttling back to idle.

Also, it does not appear to be running too rich. And I tried bumping up the idle speed a bit to see if that prevented it from bogging down but that didn't seem to help. The thing runs awesome outside of this issue. Starts right up and is surprisingly quick for a 4 cyl. I really want to get this straightened out so I can take her out a few more times before the end of the season. I have a lot of planned maintenance for her over the off season. Rebuilding the carb, replacing old fuel lines, cooling hoses etc.

 

[stonyloam]

Re: Mercruiser 170 dying upon throttling back to idle.

Could be your idle mixture. Remove the screw (starboard side bottom) and make sure it is in good shape. Reinstall and turn all way in until lightly seated then back out 1 1/4 turns as a starting point.

 

[SEARAY CHRIS]

Re: Mercruiser 170 dying upon throttling back to idle.

If it seems to be loading up with fuel it sounds like a fuel related issue like carburator !!

 

[Jono69]

Re: Mercruiser 170 dying upon throttling back to idle.

Sorry for the delayed response here guys. The weather has not been cooperating up here in Northern Illinois. I adjusted the idle mixture to 1 1/4 and lowered my idle speed slightly and it seemed to run really well in the driveway. I finally got it out on the water today and it ran like a champ!! Did not die at all!! Now that it is fairly tuned up, it goes like hell!! Thank you guys for the advice once again!