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Carb Fire!!

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brewskibeans

New member
1995 Mercruiser 3.0 LX - replaced the stainless fuel line from fuel pump to carb as well as the vacuum line. When I went to fire it up, the carb not only sparked but totally caught on fire. I had to use an extinguisher to put it out. There’s probably only 2 gallons of gas in the tank so maybe it was lack of fuel (too lean)? Or timing? Suggestions?
 

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Well I’ve picked up starting fluid and it says to not start the engine without the air filter in order to prevent back fire. I believe this is my issue. I’m going to fill up the boat with gas to ensure plenty of fuel flow and put the filter on to ensure to backfire. Still open to recommendations.
 
Normal a backfire is caused by wrong ignition timing, spark when intake valves is open. Did it run before you did this work ?
 
Don't use any starting fluid. If you must prime the carb, just drizzle a little bit of gasoline into the carb...like half an ounce. If it doesn't try to catch then you should investigate spark, etc. But usually a little gas does the trick.
Staring fluid not only makes a stronger hotter burn, it's higher power explosiveness can damage your engine. It also creates an invisible haze of combustible gasses all around the outside of the engine. Any spark can set it off possibly burning you or causing damage to things.
Rely on the carb to do its thing. If it isn't then put it right.
 
This is the order in which I have the ignition cables. Can someone verify accuracy?
 

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Also an intake valve sticking open slightly can cause a backfire thru the carb like that. As a general practice I always put the flame arrestor in before starting the engine. Only takes a minute to be safe. Now i will take it off when idling if need be to check the carb but the greatest risk of a backfire is when starting. Firing order? If you don’t know you REALLY should get yourself a shop manual!
 
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