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Hard starting

roseaa

New member
"twin mercuriser inboards. ne

"twin mercuriser inboards. newer carter carbs but if the boat sits for a week, i have to pump the throttles dozens of times to start and sometimes it backfires......"
 
"Backifiring... sounds like a

"Backifiring... sounds like a timing problem. Spark plugs are firing while the intake valves are still open.
Pumping the throttle, a little bit, to start a carburated engine, especially after it sits, is normal. Take a look at the timing, then see how it behaves."
 
"Hold it! This is a common bo

"Hold it! This is a common boating problem; it has nothing to do with the ignition or a screwed up carb. The backfiring is caused by a lean out condition because the carbs are simply dry after sitting in the heated engine room--it happens all the time. Pull the carb top off after it sat for a week and you won't find a drop of gas in there.

IF this boat has electric fuel pumps, and IF the pumps run ONLY off an oil pressure switch (ON when pressure is evident), then you can do this: Add a push button by-pass switch to fill the carbs up before cranking the motor. I did this on my old boat and it worked slick.

But IF the boat has mechanical fuel pumps, then you have two choices: Install electric pumps (see above), or use the "Fastjeff Boat Leaving Method". To wit: Let the motors cool down all the way (if possible, opening the hatches to aid). Then, with the motors cool, refire and let the motors run only until oil pressure comes up. Next time you fire up there will be some gas remaining inthe carbs, and that will get them going.

Jeff"
 
So the backfiring is just becu

So the backfiring is just becuase he's pushing all that gas in and it's just lying in the intake manifold before it fires?
 
"The back firing is caused by

"The back firing is caused by a LACK of gas; a lean condiotion, like when you punch it all of a sudden and the accelerator pump can't keep up. Pow!

Jeff"
 
"Most systems have anti siphon

"Most systems have anti siphon valves at the fuel tank. Some folks have problems and remove the check ball hence the hard starting. If there is electric pumps and they are factory, do not bypass the power to them. That is unsafe. If there are electric pumps they only pump while cranking, if they are right they will provide ample fuel. If you doubt a electric pump perform pressure and volumetric tests."
 
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