How bad is running out of gas?

spiderjohn

Cadet
Joined
Jul 15, 2002
Messages
25
I have a 1976 85 Evinrude that I often run with 6 gallon portable tanks. Often I don't pay attention until the motor dies when the tank is empty before I switch over to another one. Can this cause any major damage to the motor?
 

R.Johnson

Rear Admiral
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Sep 24, 2003
Messages
4,446
Re: How bad is running out of gas?

When you run out of gas, the engine is briefly running on a lean mixture. Doing this on a regular basis could possibly cause some engine damage.
 

JB

Honorary Moderator Emeritus
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Mar 25, 2001
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45,907
Re: How bad is running out of gas?

Probably not, SpiderJohn. Many folks do the same thing.<br /><br />Moving this to General Outboard.
 

Dave Abrahamson

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May 8, 2003
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1,497
Re: How bad is running out of gas?

I don't change tanks until the motor sputters from lack of fuel.<br />And I've always pulled the gas line off the motor while running on the muffs after a day on the saltwater. I hear people on this board telling me not to(it runs the top carbs lean, no oil to the cylinders, etc...) and others say it won't hurt a thing.<br />I still do it to this day and it hasn't hurt a thing.( I just jinxed myself...huh? :eek: ) <br /><br />Dave
 

ZmOz

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Aug 13, 2003
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Re: How bad is running out of gas?

Anybody who says it won't hurt a thing doesn't know what they're talking about. The carbs definately will not run out of fuel at the same time, there fore some cylinders will be running with NO oil. Now, you can probably do that dozens of times with no noticeable damage; however, there is damage none the less. I wouldn't worry about it on a single carburetor motor, running lean for a few seconds isn't going to hurt anything.
 

robnik1

Seaman
Joined
Mar 9, 2004
Messages
64
Re: How bad is running out of gas?

If that is the case then how do you explain the Merc. 115 elpto '96. This model runs on two carbs at low rpms then four at high rpms.<br />thanks
 

ZmOz

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Re: How bad is running out of gas?

I don't know anything about that motor...but I'm sure there something special about it's design that allows it to do that. Does it actually turn off cylinders, or just carburetors? I will GUARANTEE you if you took a standard inline 6, for example, and unhooked the top carb and ran it like that, you would ruin the top two cylinders. Without a doubt.
 

robnik1

Seaman
Joined
Mar 9, 2004
Messages
64
Re: How bad is running out of gas?

I am also not sure. But am sure top 2 carbs have no low speed jets. And when accel sometimes step from low to high can be a big jump. Always ran great though.
 

Forktail

Ensign
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Feb 11, 2002
Messages
977
Re: How bad is running out of gas?

There's a difference between lean cylinder combustion, and no cylinder combustion at all.<br /><br />It's pretty hard to have a lean condition with there is no fuel available for combustion. It would take quite a bit to seize up a piston that's not firing, as the friction is minimal, and some oil should be present. BTW, many 2-strokes inject oil independently of the fuel.<br /><br />The worst thing about running tanks dry is that you suck up all the crud. IMO, if you run them dry all the time, you're probably ok. But if you run them dry once in a blue moon, then you're chances of sucking crud are greater. Either way, you definitely want an in-line filter system.<br /><br />I'd like to hear more discussion about running our EFI's dry. :confused:
 

quantumleap

Master Chief Petty Officer
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Feb 16, 2004
Messages
813
Re: How bad is running out of gas?

robnik1- the bottom 2 carbs only provide enough fuel for lubrication at low RPM's but not enough for combustion. The carbs then kick in at +/- 1800 RPM's and it fires on all 4 cyl's. :cool:
 

ufm82

Master Chief Petty Officer
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827
Re: How bad is running out of gas?

About the "sucking up the crud" reference...<br /><br /> The pick-up in tanks is in the bottom of the tank. It is always at the lowest point in the tank, or it should be. If there was "crud" in the tank, it would suck it up anyway.<br /><br /> Is that not true?<br /><br />Anyway, I prefer to simply kill the motor the first time it sputters from lack of fuel and change tanks. It may or may not hurt the engine to run it out, but why chance it? <br /><br />UFM82
 

Forktail

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Messages
977
Re: How bad is running out of gas?

The pick-up in tanks is in the bottom of the tank. It is always at the lowest point in the tank, or it should be. If there was "crud" in the tank, it would suck it up anyway.
Not necessarily. Under normal conditions only the fuel gets "sucked" and the contaminates, like water, dirt, sand, rubber, plastic remain at the bottom. They're usually heavier. Only very small and light weight particles will get sucked up with the fuel.<br /><br />But running the tank dry under throttle will "suck" whatever is there...if there's no gas. When running completely dry, I've seen chunks of rubber, gobs of sand, red plastic, and cups of water that I never knew existed.<br /><br />If you're continually sucking the tank dry, your filters might experience a drop or two of water from time to time, or an accumulation of contaminates over time. Nothing major. That's why they make changeable filters. But run it dry once in a blue moon and you're likely to fill the filter full of water and crud, plugging it or doing engine damage. At least that's my experience.<br /><br />I try not to run my engines dry. I at least shut them down when they start chugging. I completely drain my stationary tanks in the fall, and clean/flush my portable tanks. I also treat the tank from time to time for water. And I always carry an extra filter knowing that there's always some "crud" at the bottom just waiting to get to my filter. Water is the bad one, as it passes through most standard fuel filters. ;)
 

ZmOz

Captain
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Aug 13, 2003
Messages
3,949
Re: How bad is running out of gas?

That's what fuel filters are for. There's no reason to worry about sucking up anything if you have one...
 

Forktail

Ensign
Joined
Feb 11, 2002
Messages
977
Re: How bad is running out of gas?

...as long as you have a spare...and you're not busy navigating a nasty sea when you need to change it....and it's water separating...and something didn't plug the line. <br /><br />I like to rely on my fuel filters, but not depend on them...if that makes sense. ;)
 
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