Fuel Grades-gctid404385

[Guest]

Here where I live, "regular" is 85 octane. I have to buy "mid-grade" just to get 87 . I'm not a gear head so bear with me, it has to do with the altitude and atmospheric pressure, aka amount of oxygen running through the motor compares to lower altitudes. I'm not fond of the thought of running on 85 so I always buy 87.

For the boat, it's always been 87 per the merc manual, and I use sta-bil with every tank.

[Guest]

BC Steve wrote:
Thanks for clearing that up, I was going to say the choices here are between 87 to 92, never heard of anything higher without adding booster. I am going to try the regular and see what happens, as to the ethanol the only fuel here without it is Shell Premium so I will be watching for the typical water in the fuel stumble and poor starting I have had before in both trucks and boats. Do most people use a water seperator on a gas engine in a boat, I know that Bayliner puts them in on all diesels but not on gas engines.

BC Steve

2008 Bayliner 185 BR 3.0 L TKS

This is my first year with my 2004 175xt. So far I have been running mostly 87 octane with a little 89 blended in (not necessarily intentionally, just the way it worked out with gas stations pumps being busted). Power wise I feel like the boat has been running good. I haven't experienced any knocking or anything like that. But I can tell you my engine diesel's almost every time I shut her off, especially once she has been warmed up and running a while. When I bought the boat I was told by the dealer that most people with the 3.0 experience better performance with the 91/92 octane. I am going to run that through the boat for the next couple tanks and see if the dieseling goes away.

[Guest]

whitey382 wrote:
This is my first year with my 2004 175xt. So far I have been running mostly 87 octane with a little 89 blended in (not necessarily intentionally, just the way it worked out with gas stations pumps being busted). Power wise I feel like the boat has been running good. I haven't experienced any knocking or anything like that. But I can tell you my engine diesel's almost every time I shut her off, especially once she has been warmed up and running a while. When I bought the boat I was told by the dealer that most people with the 3.0 experience better performance with the 91/92 octane. I am going to run that through the boat for the next couple tanks and see if the dieseling goes away.

The dieseling (run on) is one reason that I run the higher octane, and it does help. Mostly I run 91 octane which costs me .10 a gallon more than the 87 or 89 octane (which are the same price at Holiday stations around here). For $2.50 a tank the extra $$ is worth it to me.

[Guest]

whitey382 wrote:
This is my first year with my 2004 175xt. So far I have been running mostly 87 octane with a little 89 blended in (not necessarily intentionally, just the way it worked out with gas stations pumps being busted). Power wise I feel like the boat has been running good. I haven't experienced any knocking or anything like that. But I can tell you my engine diesel's almost every time I shut her off, especially once she has been warmed up and running a while. When I bought the boat I was told by the dealer that most people with the 3.0 experience better performance with the 91/92 octane. I am going to run that through the boat for the next couple tanks and see if the dieseling goes away.

I have been running the premium fuel, 92 octane so far in my 3.0l and did have had it diesel on me coming from a high speed run to stop in a hurry but only once and temperature was close to 30 celsius that day, I belive high engine running temperature can cause it to diesel, still going to try the regular just to see, if it is a real issue I can always dump in a can of booster till i run it out. Some varying advice on this, all is appreciated, I guess I will just have to try a couple of different grades to find out what works best in my boat. I,ll post what I find out.

Regards

BC Steve

[Guest]

I checked my owners manual today and it states premium is fine if regular is not available.

[Chief_Alen]

http://www.marineengine.com/boat-for...d.php?t=380996

Give it a read. Will help with the dieseling problem.

[Guest]

I also have a 3L and initially were experiencing horrific amounts of run on/dieseling...

There are a few things you can do to reduce it from occurring;

The first thing to do is to set you idle speed at about 600rpm in neutral. Remembering you must use a digital tach to get any sort of accurate read out at this lower end of the rev range as the gauges are no good down low.

Secondly you want to richen up the idle mixture screw about half a turn, you will need the mercruiser tool for this or a small set of pointy nose pliers can also do the trick if you that way inclined.

Running HIGHER octane fuel will also help reduce it as well as keeping engine temps as low as possible... So after doing a large speed run or running for a extended period of time, throttle down slowly idle for a minute or so before shutting it off! Some even turn the blower on before they stop and idle as they think the cooler air in the hatch tends to help but I'm sceptical and don't use this technique, plus my blowers bushings must be on the way out as it makes a HELL of a squeal and am almost embarrassed to use it!

Let us know how you go!

Cheers,

Chris

[Guest]

Chief Alen wrote:
http://www.marineengine.com/boat-for...d.php?t=380996

Give it a read. Will help with the dieseling problem.

You sure you referenced the correct thread?

[Guest]

Fish-a-Palooza wrote:
You sure you referenced the correct thread?

I am pretty sure he got it right, when you read the posts, half way down one member writes on ways to stop the hard stopping of the engine (doesn't actually call it dieseling).

[Guest]

Quick update...

After using mostly 87 octane for the first couple months I've had this boat (and experiencing a ton of dieseling; almost everytime I shut the engine down) I filled her up with 92 octane the last go around (tank probably had 6 gallons of 87 octane left and the rest was filled with 92) and what a difference. No more dieseling and she ran real nice. At the low end I experienced an occasional hesitation at of the hole shot at partial throttle, like she was choking on too much fuel (or the octane was a little too high for the low rpm load). I am going to fill her with 89 on the next go around to see if I can find a nice balance. Just wanted those 3.0L owners to know, octane does make a difference with this engine.

[Guest]

92 octane will NOT make it have a hesitation. Has nothing to do with that.

[Guest]

hi i own a 220mpi in my 192 while my friend owns a 190hp carb 192,these mercruiser engine be it the 3l or the v6 or the v8 are old school engines they are not hi tech eg 4 vavles per cyclinder variable cam timming and so on.Its the electronics on them that make them hi tech & are still behind the times compared to the auto industry.I have run my 192 on e10 or some call it e85 & premium no difference,while may friends 192 has some promblems like mentioned on the 3l,what i am trying to say is on later motors you will not have these problems with efi,, as for the ignition they run a crank angle sensor which tells the computer whats going on so the computer retards or advances to suit the condition .1 day they will put this stuff on the 3l,fingers crossed

[Guest]

tassjo wrote:
I have run my 192 on e10 or some call it e85 & premium no difference,

E10 and E85 are very different and you should never put E85 in an engine that was not specifically designed for it.

[Chief_Alen]

#7

I grew up with carb cars. To start and run a carbed engine is different then fi. Start the engine allow the engine to warm up so the choke is open maybe 3-4 minutes. After a hard run idle the engine 3-4 minutes and then shut down.

99% of the time there will be no dieseling.

[Guest]

+1 on chief's post