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Mercruiser 5.0, advance throttle not squirting gas into carb, won't turn over

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dbarwi1

New member
When I advance throttle my Mercruiser 5.0, I do not see gas being squirted into the carburetor. As a result, if it sits for a week or so, it won't start no matter how many times I pump the throttle. If I add gas to the carburetor, it starts up and runs until I turn it off so I don't think it's the fuel pump. Also, I replaced the carburetor and that did not resolve the issue. In both the old and new carburetor, it will start up only when I add a little gas to the carburetor first.

What would prevent the advance throttle process to not give gas to the carb to get it started?

Thanks!
Daniel
 
no fuel in the float bowl....

the 'gasoline' of today evaporates very readily and it is very common for the contents of a float bowl to be gone in a few days, especially when the engine box is heated by the sun...
 
The engine starts on the contents of the float chambers, not on the squirt from the accelerator pump. No start equals no fuel. Perhaps there is a restriction in your supply somewhere? How old is the vessel? Does it still have the original fuel plumbing?
 
o2batsea said:
The engine starts on the contents of the float chambers, not on the squirt from the accelerator pump. No start equals no fuel. Perhaps there is a restriction in your supply somewhere? How old is the vessel? Does it still have the original fuel plumbing?
Click to expand...
The boat is from 2001. It probably has the original fuel plumbing. The fact that once it gets started it runs until I turn it off, would it still be a restriction in thr fuel lines?
 
Loss of prime after sitting.

Your engine has a electric fuel pump by the way or it should for the year of it.

The electric fuel pump should function during cranking. It by passes the oil pressure switch during cranking.

When the key is in the run position the oil pressure switch if not made with ~ 5-7 psi will kill fuel pump.

So, you need to determine if fuel pump is running when cranking.....start there
 
Got it. I just replaced the fuel pump 2 years ago so hopefully that is not it. Knowing that the fuel pump is probably new, what else might stop the fuel pump from functioning during cranking?
 
One more thing I thought I'd mentioned. I just noticed that the electric choke wasn't fully closing the flap all the way. I will be adjusting that this afternoon. I'm not certain that would be the cause of anything but I thought I'd mention it.
 
As mention by other contributors.... Today's gas evaporates more quickly than before and therefore leaving the boat unused
for a period of time will result in you having the to crank the engine to fill the bowl with fuel.... again. Don't chase your tail on this.
Even with a working electric fuel pump, I need to crank my engine for a period of time ( I never crank than 5 to 10 seconds at a time to avoid overheating the starter) . I often have to do this a half dozen times. My regimen ( if boat hasn't been run in a while.... weather dependent ) . Crank engine for 5 seconds, pause ( 10 ish secs), crank again, pause, crank again, pause, pump throttle two to three times, leave throttle partially cracked open.... crank again.. pump throttle... engine usually comes to life about this time. If just overnight or a day or two engine starts on first crank. Choke plates almost never close all the way unless its below freezing.
 
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