Inselaffe
Well-Known Member
Is running the carb dry on my 4-stroke Yamaha 9.9HP outboard likely to have any adverse affects, especially with respect to the fuel pump running with no petrol feed to it?
Thanks
Thanks
Running Carb Dry?
- Thread starter Inselaffe
- Start date
ShipsWoofy
Well-Known Member
I don't think so. I try to shut my fuel off so the outboard runs out of petrol as it reaches the slip in Sunday nights. I regularly get this wrong and end up drifting out to the harbour entrance.
I do it to stop the car stinking of petrol as the full float chamber leaks into the boot.
Never caused a problem yet.
I do it to stop the car stinking of petrol as the full float chamber leaks into the boot.
Never caused a problem yet.
Malcb
Well-Known Member
Probably not, but there is no need to run the carb dry on a four stroke as you would on a two stroke.
VicS
Well-Known Member
Cant see any problems. I've always done it with two strokes. Should be even less objections with a 4 stroke, but as malcb says less reason to do so.
npf1
Well-Known Member
malcb - I've got a Honda four stroke and it does leak all over the back of the car if I don't let it run dry. Is there something I should be doing that I'm not? Thx
Malcb
Well-Known Member
Not had much experience with laying down four strokes. The only thing that sprigs to mind is "Are you lying it down the right way round" as I understand that to be critical.
oldharry
Well-Known Member
[ QUOTE ]
Not had much experience with laying down four strokes. The only thing that sprigs to mind is "Are you lying it down the right way round" as I understand that to be critical.
[/ QUOTE ]
... thi is to stop sump oil running up the bores and seeping into the combustion chanber fouling the plugs, and in extreme cases locking the engine hydraulically. Also the breather will be on the 'up' side when its lying down, again preventing oil from leaking out. The carb bowl breather if there is one would also be aligned that way, and the carb designed so that petrol cannot leak from it into the manifold.
But AFAIK there shoud be no problem running the carb dry first probably a good thing before moving the engine
Not had much experience with laying down four strokes. The only thing that sprigs to mind is "Are you lying it down the right way round" as I understand that to be critical.
[/ QUOTE ]
... thi is to stop sump oil running up the bores and seeping into the combustion chanber fouling the plugs, and in extreme cases locking the engine hydraulically. Also the breather will be on the 'up' side when its lying down, again preventing oil from leaking out. The carb bowl breather if there is one would also be aligned that way, and the carb designed so that petrol cannot leak from it into the manifold.
But AFAIK there shoud be no problem running the carb dry first probably a good thing before moving the engine
npf1
Well-Known Member
always put it the right way around when lying it down. Think I'll continue letting it run dry!
A
Anonymous
Guest
Don't you have a priming bulb? If you squeeze that first then there should be fuel all the way through the system and a full float chamber. If you don't prime it then the pump will run dry...don't know if that's a problem but why not just prime it anyway, and it should start more quickly.
G
Guest
Guest
Priming bulb ???? Think you\'ve misunderstood the post ...
He's talking about stopping the engine by running dry - to stop gumming of carb, leaking fuel in boot of car etc. etc. Not starting or general running .....
Well that's how I read it.
And my penny's worth is - I run outboards dry when finished with them .... no problem.
He's talking about stopping the engine by running dry - to stop gumming of carb, leaking fuel in boot of car etc. etc. Not starting or general running .....
Well that's how I read it.
And my penny's worth is - I run outboards dry when finished with them .... no problem.
A
Anonymous
Guest
Re: Priming bulb ???? Think you\'ve misunderstood the post ...
[ QUOTE ]
He's talking about stopping the engine by running dry - to stop gumming of carb, leaking fuel in boot of car etc. etc. Not starting or general running .....Well that's how I read it.
[/ QUOTE ]
Well, this is how he actually wrote that question (as opposed to the question that everyone answered)...
[ QUOTE ]
Is running the carb dry on my 4-stroke Yamaha 9.9HP outboard likely to have any adverse affects, especially with respect to the fuel pump running with no petrol feed to it?
[/ QUOTE ]He is asking whether running the engine out will damage the fuel pump, not leaking fuel and gumming. And that is the question I gave my opinion on.
[ QUOTE ]
He's talking about stopping the engine by running dry - to stop gumming of carb, leaking fuel in boot of car etc. etc. Not starting or general running .....Well that's how I read it.
[/ QUOTE ]
Well, this is how he actually wrote that question (as opposed to the question that everyone answered)...
[ QUOTE ]
Is running the carb dry on my 4-stroke Yamaha 9.9HP outboard likely to have any adverse affects, especially with respect to the fuel pump running with no petrol feed to it?
[/ QUOTE ]He is asking whether running the engine out will damage the fuel pump, not leaking fuel and gumming. And that is the question I gave my opinion on.
Marmalade
Well-Known Member
Re: Priming bulb ???? Think you\'ve misunderstood the post ...
I too have the Honda 4 stroke - and it's the leakiest thing ever - others say the same. Running the carb dry does help to keep the car boot fuel free - in anything other than upright it leaks (and yes I do put it down on the correct side!)
Simon
I too have the Honda 4 stroke - and it's the leakiest thing ever - others say the same. Running the carb dry does help to keep the car boot fuel free - in anything other than upright it leaks (and yes I do put it down on the correct side!)
Simon
JimGrandy
New Member
The Mechanic Said......
Just got my Honda 2HP 4-stroke back from my mechanic. He did the usual tune-up but also had to spend a lot of time cleaning the carb. He said that I should always run it out of gas if I'm not planning to use it for 24 hours. He said it doesn't hurt the carb and it keeps the gunk from building up in the carb after the volatiles evaporate. He owns the same motor.
Just got my Honda 2HP 4-stroke back from my mechanic. He did the usual tune-up but also had to spend a lot of time cleaning the carb. He said that I should always run it out of gas if I'm not planning to use it for 24 hours. He said it doesn't hurt the carb and it keeps the gunk from building up in the carb after the volatiles evaporate. He owns the same motor.
Boathook
Well-Known Member
I always run my honda 30 dry at the end of the weekend or holiday. No problems yet after 7 years ! I just disconnect the fuel line at the engine and leave it running ... and then it stops !!
Drascomber
Well-Known Member
Running the carb dry on a 2 stroke stopped you from ending up with a carb bowl full of only oil when the petrol evaporated. Running the carb dry on a 4 stroke stops you from ending up with a carb bowl full of gelled mush when the petrol goes past its sell by date. However, that can take a couple of years or more.
The guys who calibrate new petrol engines for the manufacturers (the real experts) tell me that running the carb dry is a bad idea 'cos the conditions in the cylinder when the mixture goes seriously lean are real bad for the engine - but then they may just be purists.
So since I don't have to drain the carb to stop it leaking I run it dry just at the end of the season.
The guys who calibrate new petrol engines for the manufacturers (the real experts) tell me that running the carb dry is a bad idea 'cos the conditions in the cylinder when the mixture goes seriously lean are real bad for the engine - but then they may just be purists.
So since I don't have to drain the carb to stop it leaking I run it dry just at the end of the season.
ShipsWoofy
Well-Known Member
If they are talking about car engines with injectors then yes it is not good to run out of fuel, the computer has a hernia too. But simple putput outboards are a different ball game entirely.
Lakesailor
Well-Known Member
[ QUOTE ]
running the carb dry is a bad idea 'cos the conditions in the cylinder when the mixture goes seriously lean are real bad for the engine
[/ QUOTE ]
But the engine is not running under load and won't overheat in a few seconds. No problem.
running the carb dry is a bad idea 'cos the conditions in the cylinder when the mixture goes seriously lean are real bad for the engine
[/ QUOTE ]
But the engine is not running under load and won't overheat in a few seconds. No problem.
A
Anonymous
Guest
If you have access to people in a 4 stroke outboard factory, you might be able to find out why 'everyone' is having carb issues with 4 strokes whereas 'most' people with small 2 strokes never had any trouble and didn't even service them!
Environmental requirements have been tightened enormously along with the introduction of 4 strokes making carb settings more critical. Is that part of the problem?
Environmental requirements have been tightened enormously along with the introduction of 4 strokes making carb settings more critical. Is that part of the problem?
Inselaffe
Well-Known Member
Thanks for the replies,
I should have been more specific, I was talking about avoiding leaving petrol in the carb and gumming it up when it evaporated when left for a while.
I thought it wouldn't be so critical as for a 2-stroke but, also thought that even petrol on its own left residues as it evaporated.
The motor is in a well, and since it weighs 40 odd kilo, and the prop won't fit throught the well opening, it stays on the boat, in the water.
It's the older Yamaha 4-stroke 9.9HP with the vacuum activated choke system. There are three interelated thermostats for this system (!) I have got the flow diagrams from Yamaha and sorted out the carb, and finally it starts easily and runs perfectly, particularly the tickover isnt so temperemental anymore.
Anyway, I know from experience how sensitive the motor is to muck in the carb, and I want to keep it running the way it is and thought that running it dry might help keep it so.
From the replies I think that it probably won't damage the motor, but also that maybe gumming up shouldn't be a problem anyway?
I should have been more specific, I was talking about avoiding leaving petrol in the carb and gumming it up when it evaporated when left for a while.
I thought it wouldn't be so critical as for a 2-stroke but, also thought that even petrol on its own left residues as it evaporated.
The motor is in a well, and since it weighs 40 odd kilo, and the prop won't fit throught the well opening, it stays on the boat, in the water.
It's the older Yamaha 4-stroke 9.9HP with the vacuum activated choke system. There are three interelated thermostats for this system (!) I have got the flow diagrams from Yamaha and sorted out the carb, and finally it starts easily and runs perfectly, particularly the tickover isnt so temperemental anymore.
Anyway, I know from experience how sensitive the motor is to muck in the carb, and I want to keep it running the way it is and thought that running it dry might help keep it so.
From the replies I think that it probably won't damage the motor, but also that maybe gumming up shouldn't be a problem anyway?
G
Guest
Guest
Re: Running Carb Dry? Now with little more info and explanation.
Thanks ... now I will answer from the fuel standpoint.
Leaving gasoline in any container such as carb bowl will eventually result in a denser fluid due to evaporation of light ends in the blend. Long term you will have gumming up from octane boosters and other agents in the blends. The running characteristic of the fuel will decline as the octane and density change. You will not suffer 2T deposits of course but that is only a small advantage compared to the other losses.
If you were running an engine dry repeatedly a number of times each day after short runs - then I would be cautious about it ... and say only run it dry after a series of runs etc. basically before leaving it standing for appreciable period. If the engine is regularly used through the season - then also not necessary. But yes definitely before removal from boat, when leaving engine stationary for extended periods etc.
A 4St engine can suffer fuel in carb for reasonable periods actually ... my Briggs and Stratton Garden Tractor sits all winter etc. with fuel in tank and carb - starts next spring ok. But then again - I'm lazy and often don't take my own advice !
Thanks ... now I will answer from the fuel standpoint.
Leaving gasoline in any container such as carb bowl will eventually result in a denser fluid due to evaporation of light ends in the blend. Long term you will have gumming up from octane boosters and other agents in the blends. The running characteristic of the fuel will decline as the octane and density change. You will not suffer 2T deposits of course but that is only a small advantage compared to the other losses.
If you were running an engine dry repeatedly a number of times each day after short runs - then I would be cautious about it ... and say only run it dry after a series of runs etc. basically before leaving it standing for appreciable period. If the engine is regularly used through the season - then also not necessary. But yes definitely before removal from boat, when leaving engine stationary for extended periods etc.
A 4St engine can suffer fuel in carb for reasonable periods actually ... my Briggs and Stratton Garden Tractor sits all winter etc. with fuel in tank and carb - starts next spring ok. But then again - I'm lazy and often don't take my own advice !