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Gas Line - To Yank or Not to Yank

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204013391
Deckhand

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Initially Posted - 03/28/2004 : 15:58:12

I have seen different accounts here and there about how to "decommission" an outboard between uses. The philosophy I have adopted is as follows. I would like feedback as to if this is felt to be a best practice or does more harm than good. What's your experience?

When I arrive at the boat, I attach the gas line to the motor ('84 8HP Johnson Sailmaster), pump the ball stiff and give it a few pulls. If it's been a week or two since I last ran it, it starts. If it doesn't, I take a break and get other stuff on the boat ready to go. I go back, make sure the ball is still stiff and give it a few more pulls. If it didn't start earlier, this set of pulls usually gets it going.

During the sail, I use the motor's kill switch. When I'm docked - unless I know I'll be back within a week - I disconnect the fuel line and let the motor run until it runs itself out of gas.

I have seen no pattern to ease of starting with killing the engine or letting it run itself out of gas.

Am I protecting it or am I damaging my motor by doing this (lubrication, dried seals, etc.)?

Troy
Second Wind (3716)
www.troyandcheryl.com

Edited by - on

Dave Bristle
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Djibouti
10005 Posts

Response Posted - 03/28/2004 : 17:14:34

Conventional wisdom is to run it dry to prevent varnishing in the float tank and the carb... What does the manual say? (You know the old saying--when all else fails...)

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Derek Crawford
Master Marine Consultant

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Response Posted - 03/28/2004 : 18:44:52

I have a mechanic friend who is a genius with any form of infernal combustion engine. He's also a more-than-competent racer. He told me that if you are using the motor at least every 2 months, it is not necessary to run it dry which perhaps could be damaging.
Derek

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/28/2004 : 18:47:37

With my old Johnson 9.9 and with my current Mercury 8, I've always just cut the motor upon arrival at the dock, then left the fuel line attached and I've never had a problem.

Edited by - on

skipn809
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Response Posted - 03/28/2004 : 18:51:11

I do like Don, except I disconnect the fuel line. I was told pressure would build in the line forcing extra gas into the carb, which could be a problem with getting into the cylinders. Seems to have worked OK for several years.

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Buzz Maring
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Response Posted - 03/28/2004 : 18:52:31

I have a mechanic friend who is a genius with any form of infernal combustion engine. He's also a more-than-competent racer. He told me that if you are using the motor at least every 2 months, it is not necessary to run it dry which perhaps could be damaging. - Derek

Hi Derek,

Did he happen to mention why running the engine out of fuel might be damaging?

Edited by - on

Gloss
Master Marine Consultant

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Response Posted - 03/28/2004 : 18:58:32

Hey Derek,
What does your mechanic friend say about always adding fuel conditioner to the fuel, or even more than the required amount to keep parts clean. Or does he recommend something else to keep our engines tip top.

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Derek Crawford
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Response Posted - 03/28/2004 : 23:45:36

Buzz - no he didn't say why (and I was too naive to ask!)
Frank - he said that fuel additives were a waste of money, that 2-strokes pretty much "looked after themselves" with only normal maintenance. (This is the man who, after our C-22 went down, dove on her and brought up the motor and had it running perfectly by the next day!)

Derek

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Leon Sisson
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Response Posted - 03/29/2004 : 01:19:03

<center>Run the carb dry, or let the fuel curdle in there?</center>

After docking at the end of an outing, I always disconnect the fuel line at the engine, and then run the engine, in gear, at high throttle, until it runs out of fuel in the carb, fuel pump, etc.

{I'm quite convinced this does the engine no harm, but deleted my 3 paragraph lecture as an act of generosity and mercy.}

The best approach might be to drain the carb after switching off the engine, but how practical is that on an outboard?

-- Leon Sisson

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Buzz Maring
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Response Posted - 03/29/2004 : 08:01:56

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Leon Sisson
 <center>Run the carb dry, or let the fuel curdle in there?</center>

After docking at the end of an outing, I always disconnect the fuel line at the engine, and then run the engine, in gear, at high throttle, until it runs out of fuel in the carb, fuel pump, etc.

Why high throttle, and why keep it in gear?

{I'm quite convinced this does the engine no harm, but deleted my 3 paragraph lecture as an act of generosity and mercy.}

Well, believe it or not Leon, some of us actually read what you post.

The best approach might be to drain the carb after switching off the engine, but how practical is that on an outboard?

-- Leon Sisson
<hr height="1" noshade id="quote"></blockquote id="quote">

OK ... based on that last statement, it sounds like you DO think it is important to get the fuel out of the carburetor ... can you tell us (in 10 words or less

) why?

Thanks!

(edited for spelling of carburetor ... 'should've just called it a "carb" like Leon did)

Edited by - Buzz Maring on 03/29/2004 08:04:52

Gloss
Master Marine Consultant

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1916 Posts

Response Posted - 03/29/2004 : 09:35:09

Derek,
I should have been more specific in my question.

What does your mechanic think of additives for 4 stroke engines. Especially Hondas with very small jets, or orifices, or whatever it is that seems to get clogged up.

That reminds me, I need to add an in line fuel filter

Edited by - on

RoofRoof
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186 Posts

Response Posted - 03/29/2004 : 10:24:26

My Honda was a terminal jet clogger.

I now use Stabil fuel stabilizer, and Techron fuel additive.

I have always been of the opinion that if a little is good, then more is better. So, I use more than the recommended amount of both.

So far, no jet clogging anymore.

Edited by - on

Derek Crawford
Master Marine Consultant

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Response Posted - 03/29/2004 : 10:53:40

Frank - unfortunately my mechanic is now living in Scotland (he's also a self-trained computer whiz and has a job with a hi-tech company over there...). Never having owned a 4-stroke I had no need to ask him about that - all his comments refer only to 2-strokes. I sure wish he was still here - I need my timing belt changed on my Mazda...

Derek

Edited by - on

tmhansen
Captain

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397 Posts

Response Posted - 03/29/2004 : 15:55:04

I follow the same practice above- disconect the fuel line and run the carb dry. I do it when I flush the engine after I'm back on the trailer so I don't put it in gear. It can take a while even if I run up the RPMs a little bit.

My little Honda 2.5 has a valve to kill the fuel supply for this purpose. I think the idea of engine damage has to do with 2 strokes that use fuel to lube the cylinder walls. Since both my engines are 4 stroke(I live in California) I don't worry about it.

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
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Response Posted - 03/29/2004 : 19:57:12

I've been thinking about this "disconnect the fuel line or not" issue all day and I can't think of one good reason to disconnect the fuel line unless you are putting the motor up at the end of the season. Quite honestly, I can't think of one good reason to run the carb dry either.

I thought maybe with the motor run dry of fuel, it would it would prevent varnish build up, but why is it after mowing the lawn, no one disconnects the fuel line on their mowers and runs the carb dry? Or after using the snowblower, weedwacker, leaf blower, edger, roto-tiller, chainsaw, lawn tractor, jet ski, snowmobile, inboard gas or diesel,...or their automobile? Why only outboards?

I also thought that maybe by disconnecting the fuel line, fuel couldn't be forced into the carb and flood it, but doesn't an outboard have a float that would prevent the fuel from over filling the bowl?

Then I thought, well what if I ran the fuel from my lines and motor, then what? Well, instead of fuel in the lines, I would have moisture ladened air which is a bad thing. This is why it is recommended to keep tanks full over the winter to prevent moisture from getting into the fuel system.

And lastly, in two-stroke motors the fuel is also the lubricant, and I can't convince myself into believing that running a motor dry until it is out of lubricant won't have any effect whatsoever on the moving parts.

Can someone convince me?

Edited by - dlucier on 03/29/2004 23:43:09

dhunt
1st Mate

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USA
83 Posts

Response Posted - 03/29/2004 : 21:01:00

Disconnect if you are in a high sunlight area (stern faces southwest?) at the slip. The hose life will be extended if you push it back into the hull. (A tip . . . rubber products like to be sprayed with PAM . . . cooking oil substitute . . . to keep them flexible and extend their life . . . I use it on CV boots) Other than that, I really can't see any reason to disconnect or run the carb dry during a normally active season. Use the engine - use the boat . . . if you have to winter on the hard, then move south or follow the manufacturers recommendations for storage.

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Dave Bristle
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Djibouti
10005 Posts

Response Posted - 03/29/2004 : 21:43:48

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by dhunt
 Disconnect if you are in a high sunlight area (stern faces southwest?) at the slip. The hose life will be extended if you push it back into the hull. (A tip . . . rubber products like to be sprayed with PAM . . . cooking oil substitute . . . to keep them flexible and extend their life . . . I use it on CV boots) Other than that, I really can't see any reason to disconnect or run the carb dry during a normally active season. Use the engine - use the boat . . . if you have to winter on the hard, then move south or follow the manufacturers recommendations for storage.
<hr height="1" noshade id="quote"></blockquote id="quote">

I'll suggest a high SPF sunblock in place of Pam. With a 2-stroke, one issue with gas remaining in the float bowl for more than a couple of weeks in the sun is that the gas will evaporate while the oil won't. A friend's 2-stroke Merc ran and then stalled after about 6 weeks of disuse, baking in the sun. He ended up adrift in a serious current in a narrow channel. He had started it with a shot of starting fluid, and it seemed to be OK... I'm not sure about the cause of the stalling, but the crock-pot effect would seem to apply.

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/30/2004 : 09:17:18

Here's a bit of info I found at the Chevron website concerning potential problems with particles in gasoline.

From the Chevron website....

Oxidation

Except for any added oxygenates, gasoline is made up almost entirely of hydrocarbons–molecules constructed from the building blocks of elemental carbon and hydrogen. Hydrocarbons, as a class, are chemically stable molecules.

However, there are types of hydrocarbons (olefins and diolefins) that can combine slowly with the oxygen in the air ("oxidize") at ambient temperatures. The products of the reaction are larger molecules, collectively called "gum."

The gum-forming reactions become faster as the temperature of the gasoline increases. This is why this bulletin recommends controlling the temperature of stored gasoline.

Most gasolines contain negligible amounts of gum when they are manufactured, and most contain special chemicals ("stabilizers") to retard gum formation. It is the stabilizers that make it possible to store Chevron gasolines for a year when the conditions are good.

Soluble Gum

The gum formed by oxidation is usually soluble in gasoline. However, it remains behind as a sticky residue when the gasoline evaporates. Since gasoline begins to evaporate in the carburetor of a carbureted engine or in the injector of a fuel-injected engine, a gasoline containing soluble gum may leave a deposit on these parts and on the intake valves. These deposits will be in addition to the deposits normally formed by a gum-free gasoline — a formation triggered by the elevated engine temperatures.

Modern engines are designed to run best when vital engine parts are clean. Carburetor and fuel injector deposits can cause hesitation and stumbling on acceleration, lower fuel economy, lower power output, and higher emissions of hydrocarbons and carbon monoxide. Excessive intake valve deposits can cause many of the same performance problems, plus higher emissions of hydrocarbons, carbon monoxide, and nitrogen oxides.

Because the Federal Environmental Protection Agency recognizes that fuel system deposits increase emissions, they require all gasolines to contain a deposit-control additive. All deposit-control additives keep deposits from forming; the best ones clean up deposits formed by lower-quality gasolines.

If the gasoline contains a lot of soluble gum, the normal level of deposit-control additive may not be sufficient. This is why Chevron recommends treating a tank of gasoline with an extra dose of deposit-control additive if a vehicle displays driveability problems after being stored. (Note: Chevron does not recommend adding a deposit-control additive to the fuel for a two-stroke-cycle engine.) The gum-forming reactions become faster as the temperature of the gasoline increases.

Insoluble Gum

Severe oxidation of gasoline may produce insoluble, as well as soluble, gum. The insoluble gum will take the form of brown or black particles which float in the gasoline or settle to the bottom of the container.

When an engine is fueled with gasoline containing insoluble gum, the fuel filter will remove the gum. If the engine has an in-tank fuel pump, the screen on the pump's feed also may capture some of the gum. However, these devices can become plugged if the gasoline contains too much insoluble gum. This will cause the engine to lose power or stall because it is starved for fuel. Adding a deposit-control additive will not keep insoluble gum from plugging filters and screens.

***************************************************************

From reading this, I assume that in order for the gasoline to oxidize and form carb clogging gum, oxygen must be present. This would lend credence to keeping fuel tanks (and lines) full and sealed as well as leaving the float bowl full to reduce the oxygen supply, thus minimizing oxidation.

Edited by - on

Sid
Navigator

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Response Posted - 03/30/2004 : 10:35:33

Run two strokes dry at your own risk. As Don states, the lubricant is in the fuel, and dry pistons can cause a lot of damage over time. I know those that have done it for years without a problem, but also a couple who had to rebuid motors because of it. Better safe than sorry.
If your engine doesn't sit for a long time in excess heat, you should have minumum evaporation from the float bowl in your carb. That is where most of your gum build up takes place. When new fuel is introduced into the bowl, the gum particles are floated with the fresh fuel flow into your jets and clog the carb.
My procedure is to use the kill switch, disconnect fuel line and store out of sunlight, top off tank to reduce condensation. Next time out, reverse and go. Every winter(not spring), clean carb with spray before it's stored to reduce deposits as it sits and dries over the winter. You could drain the float bowl as well. (I usually don't fog my engine because I use the boat a few times over winter.)Give it a shot of cleaner at spring commissioning as well, clean or replace plugs and you should be good to go.

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John Sines
Deckhand

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Response Posted - 03/30/2004 : 11:01:50

Techron is not a bad idea. Seafoam in exactly the recommended amounts in all four stroke crankcase oil is a great idea. In small engines you must measure the right amount. The only other product for gasoline I know that is used is BG 44K, which I would describe as a highly concentrated version of techron. Carb's require maintenence as the Chevron article said, there will be things that will collect and must be cleaned out manually. I would install a filter some of the bad stuff is not gasoline. If you have a two stroke and mix in too much oil, it will collect in the float bowl as the gas evaporates. With oil and two strokes and gasoline additives some is OK and more is frequently a problem. The closer you mix the oil and gas and use the brand of oil as specified by the manufacturer the better your two stroke will run. I would read the can. Your gas tank has a vent and your carb may or may not. The fuel bulb in the gas line has a check valve and the fuel will be forced into the float bowl. The float bowl will have fewer deposits if it is stored full. So you should disconnect your fuel line or remove the the bulb. You should not run the engine out of gas even if it will be months before you use it. You should add techron and stabil to your fuel in sparing amounts exactly as the cans say to. You may need to address problems with water in your fuel, a good filter will trap water. If you must run a two stroke out of fuel it is better if it is allowed to idle and not to rev it up, think of it slowing down with no oil. I would say however that I have a 81 Honda BF100 and I have never disconnected the fuel line, used stabil, or any other additive, have never run the carb out of fuel, and have not had problems with it starting in eleven years of sailing. It is dead now the impeller went and it got hot. Outboards use fuel system technology that is frequently older than I am. As a side note I would say that it is common for people to remember the good in the past and from the perspective of their well made fuel systems in cars they expect there other engines to run as well. I think they never did run that well. Cars are really well made and boat engines that are small still run like cars did in 1970. Other small engines run better for different reasons; they do not come off idle under load and there idle speed is equivalent to half throttle and they are run wide open most of the time.

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Gloss
Master Marine Consultant

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Response Posted - 03/30/2004 : 19:13:58

So what is Seafoam?

Is that what you get when you pee off the transom?

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/30/2004 : 19:19:23

Well, since no one has yet to convinced me that disconnecting the fuel line and running the motor dry is better than leaving the fuel line connected, I guess I'll continue to leave it connected.

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seastream
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Response Posted - 03/30/2004 : 20:40:07

I just kill the engine (1987 'Rude 9.9 2 stk) without running it dry. I do disconnect the fuel line from the tank when leaving when the weekend's over ever since the engine flooded because of pressure buildup. No problems since.

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John Sines
Deckhand

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Response Posted - 03/31/2004 : 00:18:45

SeaFoam is an oil additive available at Walmart and similar stores and every auto parts store anywhere I have been. A very old company and product that will dissolve carbon deposits from rings and oil passages, ect.

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Doug
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Response Posted - 03/31/2004 : 00:42:54

When I bought the new Yamaha they had it running in a test tank. He went to answer the phone and I (like always) reached up and popped off the fuel hose to run it dry for shut down. The engine made a ticking noise as it ran dry. Mechanic that was in the shop explained than the motor had a fuel pump and they did NOT recomend running it dry. If the fuel's going to sit for a long time they suggested a fuel stabilizer, but that's about it.

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Raskal
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Response Posted - 03/31/2004 : 01:24:34

<blockquote id="quote">quote:<hr height="1" noshade id="quote">why is it after mowing the lawn, no one disconnects the fuel line on their mowers and runs the carb dry? Or after using the snowblower, weedwacker, leaf blower, edger, roto-tiller, chainsaw, lawn tractor, jet ski, snowmobile, inboard gas or diesel,...or their automobile? Why only outboards?<hr height="1" noshade id="quote"></blockquote id="quote">

The Fisher's Island Ferry never comes bearing down at you from the end of the driveway when you can't get the mower started, does it?...

Rich K.

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