1995 Merc 150 hp idle issue

good day to all,

My 1995 Merc 150 hp carbed engine has begun to have an idle issue all of a sudden. The boat lives in a lift at my dock and has been very reliable up till now. Had it out the other day and engine did not want to idle at low RPM without stalling. Once stalled engine was hard to restart but, eventually would and did fine as long as rpm were higher than normal idle. I returned to my dock and removed cowl to give it the once over. I discovered what appears to be a vaccum line that was split at the connection nipple at the top cylinder on left looking aft. I trimmed split end and reattached. My question is can this one vaccum hose cause such an issue or should I continue to troubleshoot? I have not taken boat back out on the water yet but, it seemed to do better while I was putting her back in the lift slip. I use stabil in the fuel as of late but, have not in the past and wondered if I might be a victim of Ethenol breakdown??? Oh and just for those that will ask my idle stabilizer is intact. I fthe consensus is to remove it I would also seek advice on how to do so. I look forward to all input and I pass "Thanks" in advance.

Re: 1995 Merc 150 hp idle issue

really any help would be appreciated?

Re: 1995 Merc 150 hp idle issue

A broken recirculation line could certainly be giving you the issue. Maybe dump out your fuel water sep filter if you have one, and check the contents. This is a quick item to check. Start simple.

Re: 1995 Merc 150 hp idle issue

thanks, I checked fuel and water seperator and it looks good. The other recirc lines coming from each cylinder look good and snug. None of these hoses has anything connecting them. Should I put a small tie-wrap on to ensure they don't pop off? waht is the exact function of the idle speed stabilizer? Some posts here say get rid of it others say keep? Could it be causeing my issue??

Re: 1995 Merc 150 hp idle issue

Don't bother with tie wraps. You'll end up damaging the lines in the end. In my humble opinion, idle stabilizers are great in theory, but in the end, they can end up making more issues than they solve. I've removed them from all the V-6 Merc I've ever owned. I've found that by doing so, I can dial in a better idle without them. I got a 5 mile no wake run where I am, so a nice idle is fairly important to me. Disconnect it and see if it helps. My two cents.