Mercury or Mariner motors
 

Hey guys, I have a 175 EFI Magnum the motor runs great except at idle. I have to mix my oil because the previous owner had the oil injection taken off because they burned up the powerhead. So with a rebuilt powerhead. I bought the boat and broke it in. THe engine is supposed to have a 50:1 mixture at crusing speeds and a 100:1 mixture at idle. I think that it fouls plugs at idle or when slow trolling. Anybody know any tricks for this? I dont mind changing plugs or running some stuff through it. Just looking for some experienced ideas. Thanks. Vic

Re: Mercury or Mariner motors
 

I will tell you the only thing I know for sure when it comes to the Mercs and idleing. A buddy of mine has a 175 Blackmax and it idles extremely rough. He wanted it to idle smoother and took it to his mechanic which told him that those particular motors are GREAT motors, but he could not get it to idle smoothly. He said that is just the way they are..


.kinda sounds like they are cammin to me....kinda bad!!! 8)

Re: Mercury or Mariner motors
 

Thats right Stinky, it sounds like a dragster cammin.

Re: Mercury or Mariner motors
 

Yeah there was a guy at the lauch one day with one of those 250 Mercs with the aluminum foot...it was a bass boat. MAN did that thang sound BAD!!! When hit took off :o...it sounded like a pissed off T-REX!! 8)

Re: Mercury or Mariner motors
 

I have a 1997 200 with carbs. I also had the oil injector removed (plastic drive gear-what the hell were they thinkin'?)
I have the same rough idle, and it will stall occasionally too, I have been blaming the carbs but now I am thinking different, maybe the timing is just set for speed & won't idle well.

I tried carb cleaner & it seemed to help but for a very short while, maybe it just cleaned off the excess oil?

At speed you can't find a smoother machine, a bit noisy maybe but it will cruise well & hits it when you want (mid 40's calm & trimmed).

I thought efi was the trick, I guess not - maybe a yammie is the trick.....

Doug

Re: Mercury or Mariner motors
 

I have a 175 Yamaha and I know its not a Mer. But I had a problem with the injection system and did not use it for a season. I mixed 50:1 and I had problems with pulgs and idle.
I fixed the injection last summer and I have been fine ever since!! No more plugs every other trip, no more ruff idle, and trolling is great now.

Re: Mercury or Mariner motors
 

Every carbed Merc I've been in sounds like a dragster fixin' to punch the button...sounds cool at first, but gets old when trollin'...

But, Vic, your question is about idle/cruise and oil mix...if there's a way to vary mixture when you're pre-mixing, I never heard of it...I pre-mixed my 150 Rude for years 50:1 and never had a problem...

One trick my O/B tech told me about when idleing/trolling, TILT motor UP so that back of motor is just above front of motor.to keep excess unburned oil from accumulating in the spark-plug end or "top" of the cylinder which leads to plug fouling...your cylinders are "horizontal"...think about it in terms of liquid runnin' toward the front of the motor rather than the back of the motor where the plugs are....hope I explained that to where it makes sense...won't reduce noise, that's inherant w/that motor, but it will help prevent plug fouling and smoking at idle...hope it works for you... ;) ;D ...

Re: Mercury or Mariner motors
 

vic is in the keys for 2 weeks, but I talked to him on the phone ad he took it to a tech down there and they told him it was the trigger assy. $300.00 to fix. He said he would put up with a rough idle till he gets back.

Re: Mercury or Mariner motors
 

Thanks Guy's I have a 97 200 carb merc I thought something was wrong with it because of the rough idle it does sound like a dragster when idle but when ya get on it, It goes trimed just right and calm wide open i can get 53mph but i cruse anywhere from 35 to 40 depends on how fast i want to get to the fishing spot.

Re: Mercury or Mariner motors
 

I love those engines!! Removing the oil injection is very smart!! I've heard the same advice about tilting the engine up while trolling.