Rough running and carb cleaning mith

[parrilladk]

I just discovered that my motor rough running was nothing more than an air bubble in the gas lines. I had one of my sons pump the bulb while giving the mootor gas and the rough running ended. Motor runs fine now.

I think carb cleaning is recommended way too many times here in this forum. Sometimes is called for, but for many cases it is not. Carb cleaning is at least a whole day affair for a non-mechanic with some mechanical inclination.

It seems "trigger happy" that some people recommend carb cleaning for any misfire.

I think troubleshooting should be exactly that and not just "I'm the expert: do this" type of deal.

Otherwise I have gotten really good advise here and I would recommend to anyone.

 

[Vic.S]

Re: Rough running and carb cleaning mith

Very unfair criticism of those trying to give good advice.
Trying to cover all the possibilities often with a poor description of the symptoms from distance is not easy and is bound to fail to identify obscure faults from time to time.

I dont see how an air bubble in a fuel line will give rise to rough running even now.

However in future we will refer all questions about poor running that might be due to fuel or carburation problems to to you for your expert diagnosis. Certainly will not ever think about suggesting carb cleaning unless you agree.

 

[Boblester40]

Re: Rough running and carb cleaning mith

mmm , not convinced sorry , the fuel pump will maintain the level in the carb based on the actions of the needle valve air bubbles or not when i am testing outboards i have seen 4 inch long sections of air in clear fuel tube get sucked up into the fuel pump with little affect , the fact you have open the engine right up and pumped fuel into the carb under greater pressure than the fuel pump normally delivers is proberly even more simptomatic that there was an obstruction in the carb some where which you have now cleared , every time you disconnect a portable tank you will get some air in the line .

 

[rockyrude]

Re: Rough running and carb cleaning mith

with the vaugness of some of the questions here i never cease to be amazed at how close solutions come. btw- there's not a snowballs chance in haites air bubbles caused a rough run condition.

 

[ezeke]

Re: Rough running and carb cleaning mith

Air in the fuel lines/system will definitely cause rough running and can be the primary contributing factor in running lean, a major destructive problem.

Any indications of air bubbles in the fuel or oil lines should be investigated and corrected.

In the VRO/OMS systems air entering the gasoline line will cause the oil side of the pumps to overcompensate resulting in too much oil and smoke in addition to the rough running.

See: http://www.youtube.com/watch?v=SEbW-6eOc5I&feature=channel

 

[Rick.]

Re: Rough running and carb cleaning mith

I too have used clear plastic lines from the pump to the carb. (for temporary connection) and have seen a fair amount of air in the line with no problems to report. Does it not make sense that every time you disconnect the tank the line from the connection drains of gas and then when the tank is re-connected the fuel has to void the air in that line and does so by pushing it into the float bowl? I understand a leaky fuel connection or needle packing etc. will cause unwanted symptoms but that is much different than an air pocket in the fuel line. Rick.

 

[parrilladk]

Re: Rough running and carb cleaning mith

I would have to disagree that an air pocket is nothing to worry about. An air pocket in the right location will significantly reduce the volume of gas flow, only noticeable at higher rpm's where the engine is drawing more gas. That is why, in my particular problem, the iddle would return to normal after a few seconds, when the appropriate volume of gas reached to engine. And yes, there is an over medication of carb cleaning dished out to remedy problems. I only said that carb cleaning should be recommended when appropriate, it seems that is recommmended too often without giving smart troubleshooting a chance.

I posted a problem in another post, immediately thereafter I got that I needed carb cleaning. This forum is great and I have personally benefited from it. Take the criticism however you feel, but carb cleaning is not the solution to all gas problems.