Octane?

[Dante04SRT]

Just got a new boat with a 4.3 Merc (2bbl).

I put some 87 octane in it and ran it - Seemed to run fine, no real problems (Aside from an instance of dieseling when shutting off before idling for a few seconds). Just curious if this is what is recommended. Curious if I'm using the right octane or if 89 or higher is needed.

 

[mthieme]

Re: Octane?

I run 87 octane in my 4.3 with no problem whatsoever.
The dieseling is caused by either by (most likely) the timing advanced too far or carbon buildup within the cylinder head/valves).

 

[mkast]

Re: Octane?

What RPM is the engine idling at when you shut it down?

 

[Dante04SRT]

Re: Octane?

What RPM is the engine idling at when you shut it down?

I'm not sure - I was finished skiing when it happened - I was just told about the problem afterwards.

 

[HT32BSX115]

Re: Octane?

Just got a new boat with a 4.3 Merc (2bbl).

I put some 87 octane in it and ran it - Seemed to run fine, no real problems (Aside from an instance of dieseling when shutting off before idling for a few seconds). Just curious if this is what is recommended. Curious if I'm using the right octane or if 89 or higher is needed.

Howdy,



Mercury Fuel Recommendation





Cheers,


Rick

 

[Don S]

Re: Octane?

Have you looked at your owners manual? It gives you all that information, gas, oil, gear lube, maintenance schedules etc.

 

[Dante04SRT]

Re: Octane?

Have you looked at your owners manual? It gives you all that information, gas, oil, gear lube, maintenance schedules etc.

Boat didn't come with it yet. Its being mailed from FL.

 

[180shabah]

Re: Octane?

Side note - after running hard let the engine cool down by ideling for a minute or two before shutdown

 

[JustJason]

Re: Octane?

and double check your idle rpms....

 

[chiefalen]

Re: Octane?

Most younger people don't know how to start or shut down a carbed motor.

Depends on the control, but you push the button in to give it gas without it being in gear and pump it once or twice maybe three times and leave it 1/4 of the way down should be a indent you'll feel it and than start it.

Let it warm up a minute or two than pull the control back cause you don't want it to over rev, should idle around 650-700 in gear.

Let it warm up for five minutes or so.

When after running it hard let it idle in neutral for 3-4 minutes than shut her off.

When warm no pumping just in neutral start her should fire right up, but let her idle for 1-2 minutes before running hard again.

Oh wot for 4-5 minutes at a time is ok but running wot all day every day is a bad thing.

3000-3500 rpms is a good thing all day.Whats wot on your boat 4200- 4600?

Good luck!