Engine backfire

[boater1234]

I just took my 20hp efi suzuki out for the first time today,ran awesome all day.I was suprised how much darn power this little motor has.We went to a island and beached it for like an hr or so.We had like half a tank of fuel,when i hit the throttle on the way home it just didn't have that power in the beginning.It was like it was starving for fuel but as i got going it seemed it was fine all the way home,it just happened on our way home but it was for a brief few seconds if that.Maybe the pressure wasn't built up and i needed to pump the bulb again,i didn,t think of that.When sitting for a long while do i need to pump the bulb again like any outboard even if it's an efi outboard?

2nd thing,yes i am using a few mth old fuel and i know it's not the best for it,it is ethanol free fuel but still a bit old,i had like a very light,nothing real bad backfire as i was reving it up a bit while cleaning the salt out of it.Does this mean anything or just maybe from the older gas or am i over reacting?Is it common for a very slight backfire to happen if the gas isn't newer?It only did it one time and it was more like a crackle/pop instead of a backfire.It hasn't done it but only one time and not on the water,only in my yard for a split second and it wasn't much.I'm going to be taking it down to my local lake tom to run it in some more.I just put 2 good breakin hrs on it to day and love this motor to death.It has i mean a ton of torque.Thanks for any input

 

[99yam40]

Re: Engine backfire

"I just put 2 good breakin hrs on it to day"

new motors should be run and broken in following a procedure from manufacturer.
Some call for extra oil and certain RPMs for hours
and I would not be breaking in a motor on old gas.

Some call the lean sneeze a back fire, not sure what your describing

 

[boater1234]

Re: Engine backfire

I'm trying to find out why it backfired or had a hiccup?Not about what to follow for breakin.It's prob the gas.It has stabilizer in it and it's prob 2mths old ethanol free fuel.That is not that old is it for gas?I am going to run it tom again.It ran like a bat out of hell yesterday.The only issue i had was like a small backfire like pop when i was flushing the motor out with muffs and i reved it up a bit and on deceleration it popped/crackled or what would sound like a really minor backfire only one time and that was it.

 

[JimS123]

Re: Engine backfire

2 month old stabilized ethanol should run 105%. Its not the gas. The motor is new and tight - its not broken in yet. When you flushed it you revved to too high. Add to that it was probably real hot from running like a bat out of hell, which made the parts even tighter. If you need to flush it, wait till it cools down a bit before you rev it. Or, even better yet, if you are looking for longevity don't over rev it out of the water with no load on it.

 

[boater1234]

Re: Engine backfire

Thanks jim for the reply,When i flushed it,it was over 45mins later,will it still be hot at that point?I have always flushed my outboards when i get home right away,should i let it cool down more then that?Plus when i mean a bat out of hell,i meant i gave it a good workout,not abused so i want to make sure i'm explaining myself correctly.I varied the rpms up and down for a good 2 hrs with some wot for like 5 to maybe 10 min in a spurt then backed off the throttle.It was mostly ran between half and 3/4 throttle all day with the exceptions of the wot bursts and it ran awesome.With 700lbs of total weight in the boat it was at 26.5mph and 27.5mph at wot,i couldn't be more pleased and i was actually surprised how much torque it had.This is a keeper motor for sure.With the 1442 jon boat i had and a 25hp 2stroke merc i got close to 31mph and it swallowed gas,this motor is only a few mph slower and it sips gas.

I agree i probably did rev it to high while on the flush,i usually never ever rev it but i hear a weird like vibration i thought was coming from the motor in the water,turns out it was the aluminum vibrating together from the boat.The pods in the back that are filled with foam was were it was coming from.Were the aluminum meets together and over lap,where they rivet it was were the 2 pieces or metal were vibrating.It's an older boat so i expected that somewhat.

When i reved it up a few times it was fine,the last time i reved it was where the backfire or crackle like sound happened.I was reading and it said it could of been just unburnt fuel.I guess it's nothing to worry about.I just never heard that on a 4stroke,2 stroke plenty of times.I fig since it was an efi and not carbed it wouldn't do that.

The gas by the way is non ethanol 90 octane fuel with a stabilizer called k100 in it.I see were i screwed up the post and fixed it just now,i wrote ethanol fuel by mistake.Like i said it only did it one time and very mildly.Have you ever heard of this happening and is this common to happen?

 

[99yam40]

Re: Engine backfire

so now you say it is a 4 stroke.

It is a very good idea to post what motor you re talking about in the title or at least at the very 1st of the thread so everyone knows what motor you have.

Dt or DF says a lot

 

[boater1234]

Re: Engine backfire

It says in the first sentence 20hp efi suzuki,i believe to my knowledge the only 20hp efi they make is a 4stroke.Unless they just came out with one in recent yrs which i haven't seen.Does that make any difference when it backfires 2stroke or 4stroke or is this more common with 4strokes?

 

[99yam40]

Re: Engine backfire

2 stroke back fire is due to lean air fuel ratio
4 stroke would have to spark with one of the valves open to get there

There are out board motors that are 2 and 4 stroke that in carbed and EFI configuration,
people will not go looking for what each brand motor is made in especially if you do not give the model # ,
and that model # will tell us what the motor is anyway

http://forums.iboats.com/yamaha-suzuki-outboards/must-have-year-hp-2-4-stroke-459970.html

 

[boater1234]

Re: Engine backfire

The question is since this is a brand new motor,when it backfired only once is it anything to worry about or it could of just been a fluke thing.It only did it the one time when i reved it up when flushing it out and that's all in the whole few hrs it's been run so far.I don't want to have to worry about something being wrong if it's just no big deal so that's what i'm trying to figure out.

 

[lakensea]

Re: Engine backfire

since this is a brand new motor

then why are you asking here instead of calling the dealer where you bought it?

 

[99yam40]

Re: Engine backfire

The question is since this is a brand new motor,when it backfired only once is it anything to worry about or it could of just been a fluke thing.It only did it the one time when i reved it up when flushing it out and that's all in the whole few hrs it's been run so far.I don't want to have to worry about something being wrong if it's just no big deal so that's what i'm trying to figure out.

motor should not be revved up in neutral or in gear without load on it( out of the water)
read your owners manual and talk to the dealer you bought it from

 

[boater1234]

Re: Engine backfire

then why are you asking here instead of calling the dealer where you bought it?

Because if a small backfire is not a big deal then why ask a dealer.I'm sure people here have had it happen,i just never have on a 4stroke.I never owned a 4stroke.I have had misfires here and there on a 2stroke but then they never happened again.I'm just wondering if this has ever happened to anyone else and what might of caused it.That's it.

 

[boater1234]

Re: Engine backfire

motor should not be revved up in neutral or in gear without load on it( out of the water)
read your owners manual and talk to the dealer you bought it from

I know this,as i stated in my previous posts i never usually rev up the motor when flushing it.I usually just let it idle while flushing out.The only reason i did it this time was i heard a vibrating noise i thought came from the outboard and it turns out it wasn't.I never said it was good to rev the engine up when flushing but i have done it a few times here and there in the past and never had any issues or backfires.I will call my local dealer if that's what i need to do.I'm just trying to figure out if this has happened before to anyone else with a 4stroke.I can't fathom anything being wrong with a brand new motor all though it can happen,very unlikely.I just believe it was a fluke thing.But i figured this has had to happen to plenty of people that's why i tried to figure out here first.

 

[boater1234]

Re: Engine backfire

I just got some info that makes me feel at ease.What may have happened was when i hit the rev limiter in n it makes a weird backfire like sound,so it may not of been that at all.It was just me probably hitting the limiter in n.It cuts you off so you won't run it at wot rpms for long periods of time to protect the outboard.It may be the sound i heard and not a backfire.

 

[JimS123]

Re: Engine backfire

I had a friend who threw a rod because he over-revved it. Since your motor isnt broken in enough (still tight) I guess time will tell if you did any damage.

The reason to talk to your dealer is because you already paid him for his service and he knows a lot more about it than we do.

 

[boater1234]

Re: Engine backfire

That's just the thing,how can you over rev the motor i have or any that have rev limiters.Isn't that the whole point to them so you can't blow the motor up or hurt it.It only goes up to 3000rpms i believe and cuts out.That's what i heard.I'm just going to use it as normal.If anything else happens or if it starts making weird sounds then i will worry about it.I will ask my dealer if he thinks anything is out of the ordinary though from what i heard.

 

[boater1234]

Re: Engine backfire

I just found some info that helped with this.When the over rev limiter hits on these 4strokes it makes like a misfire type sound that gets mistaken for a backfire or missfire.I believe that's what i heard.Also i found some more info that it says is very hard if near impossible to throw a rod on new modern 4stroke outboards unless it has quite a bit of wear with very little oil lubrication going to it or if the motor actually over revs which unless the motor has been modified the rev limiter will stop the damage before it can happen.They went on to say it can happen but it's near nill for that to happen on todays 4stroke outboards.

So that makes me feel at ease.I found that info reading other forums,it was actually a suzuki tech who said that as far as the backfire/missfire sound for the over rev info.The other info i found on all kinds of sites and they all concur the same info on todays new modern 4strokes.

Just to make sure i am going to call my local dealer anyway.

 

[99yam40]

Re: Engine backfire

the point of this all is do not rev it up without a load on it,

They try their best to keep people that do not know better from hurting the motor, but if you try hard enough you can still do it.
Especially if there is something actually wrong with the motor and you rev it to see if you can make it better or try to find out what the noise is by revving it.

Even you said you knew you should not be doing it

 

[boater1234]

Re: Engine backfire

Yes you are correct.I won't do that again.I use to do it with my 2strokes and never had an issue but then i didn't know better like i do now.It just makes me feel much better what i heard was a normal thing because i have never heard that before.For now on only idle on a flush.I'm sure there is no issue going on,just me being paranoid,but i guess it's better to care then not,right.This is my first 4stroke so i'm trying to learn about these outboards.Thanks for all the help.