Spray Carb Cleaner Question

[davejohnson]

Decided to use some spray carb cleaner on my old outboard ('78 Mercury 900 inline 6) this weekend. It's sat for some years with no tune-up before I got it this summer, and I think it would benefit from the treatment. I've seen some posters here argue against the spray stuff, in favor of soaking the carbs. Others I've read say the spray stuff works very well.<br />My question: How much spray is best to use in each carb, and how will I know it's enough? Should I heat the motor up for a bit first, or is it OK to use in a cold motor? If the carbs are indeed gummy or varnished, will I see an immediate improvement in performance?<br />Thanks, all. Appreciate your comments.<br />DJ in Georgia.

 

[Merc805]

Re: Spray Carb Cleaner Question

I would say that spray will not fully clean the carbs inside to the same extent as a re-build.<br />But its better than not cleaning them at all.

 

[JB]

Re: Spray Carb Cleaner Question

Yeah. What outbored said.

 

[LubeDude]

Re: Spray Carb Cleaner Question

My quick take:<br /><br />If you do not disasemble your carbs and then use the spray cleaner, you risk the chance of losening up some crud that could clog a jet and lean out your engine which in turn could seize a cylinder. Unlikly, but a deffinate posability. Do it right and dont worry. Carb kits are way cheeper than a total rebuild.

 

[jim dozier]

Re: Spray Carb Cleaner Question

Think about it for a minute. When carbs get dirty they usually get crud in the main jet and transfer orifices within the carb body or the float valves get stuck. Fuel flows from the float valve into the carb bowl then is sucked into the jets where it flows up the tube into the carb throat. When you spray carb cleaner into the throat of a carb where does it go? It goes into the throat and about all you are cleaning are the butterflies and throat surface which aren't even dirty. You have to go to where the crud is and gain access and you really need compressed air in addition to the carb cleaner when you get there. This usually requires removing and disassembling the carb.

 

[Clams Canino]

Re: Spray Carb Cleaner Question

Dirty carb lean-out leading to piston loss is a real risk for these motors. Don't cut corners.<br /><br />You can pull the starter and then the tops of all three bowls connected as a unit. Then the main jet caps and the idle needles. <br /><br />THEN you can clean most everything with the carbs still on the motor. If your carefull not to break the bowl gaskets, you likely wont need a kit.<br /><br />You'll need a wet-vac (with some water in it) and a straw taped into the hose to suck carb cleaner out and crud of the float bowls. DON'T suck gas out this way - wick it out first with a paper towel. Not for the squeemish. <br /><br />-W

 

[outboard tech]

Re: Spray Carb Cleaner Question

You can try dumping your carbcleaner into a coffee can. Drain all fuel from the carbs and use the primer bulb and hose to pump the solvent into the bowls and carbs, let soak an hour, drain and try some fuel. Only problem is you probably have the antique side bowl carbs, and draining them on the powerhead is pretty difficult. Nevertheless; a backyarder's carb job in a can. Don't forget to inspect your 30 year old molded fuel hoses, they are probably deteriorated on the inside and will refill your clean carbs with trash if not replaced. Good luck.