how do you bleed air out of fuel lines?

[jake's02-22i]

I just installed a new fuel/water separator and think I missed a step and didn't fill it up with gas. I started the engine and it dies after about 10 seconds. How do I get that air out of there? Someone told me that there should be a valve somewhere but where?

2001 350 merc. MPI.

Thanks for your help. Pictures would help a lot.

[wired1236]

I was told by my dealer to turn the key on and off several times and let the fuel pump turn off each time, (do not start it but just to the on position). When you turn the key on, you should hear the fuel pump run for a few seconds and then turn off. This will fill the fuel filter if done 5-10 times. Then try starting it.

I'm not sure about the bleed valve.

[IDBoating]

Using the fuel pump as described, by cycling the key to the on (but not start) position a few times, should do the trick. You could also just pull the filter and fill it now.

You don't need an air bleed valve on most fuel systems. The primary fuel pump(s) draw fuel from the tank in excess of the engine's demands, and the excess flows right back to the tank. That's why you have a return hose going back to the tank. Any air trapped in the fuel line will be drawn along through the system until it is pushed right back into the tank, where it will join the existing big air space at the top of the tank.

[jake's02-22i]

Thanks, I kind of just freaked out when it died. 2001 and it has never done that before. Do I have to have the fake-a-lake on when toggling the key? I will give it a try and get back to you. Thanks for the help.

[IDBoating]

You don't need the fake-a-lake to fill the fuel system, but you definitely want it when you start the engine... which I presume is the goal here, right? {grin}

Hook up the fake-a-lake. Turn the key to on and listen for the fuel pump. They generally run for ~30 seconds or so when the key is first turned on to pressurize the primary fuel system. Turn the key off. Repeat 5-6 times. Then try starting the engine again. It may take a start or two to get the engine to run constantly but if this is the only thing wrong you should be fine.

Report back!

[jake's02-22i]

Ok. Well got it run for about five minutes then I turned it off. It took a lot longer then just turning the key 10-15 times. I think that the gas even with the stabilizer in it is still bad. I will be sure to top it off with some 89 or 91 octane.

Thank you everyone for your help. Memorial day weekend will be a fun time now.

[IDBoating]

Octane won't matter. You just need fresh fuel.

Is the tank completely full? Could you siphon some/most/all of the fuel and replace it with fresh? The greater percentage of fresh fuel you can put in there, the better. You could put the old fuel in your car, truck, etc. where it too could mix with fresh(er) fuel.

[boatwakes]

On the mercruisers, the fuel rail return line returns to the filter instead of the tank like PCM so you're just recycling the air in the fuel system. On the inboard models at the front of the engine you will see the two fuel rails and their connection points to the injectors. At the front of each of those rails is a port, one with an 1/8" pipe plug and one with a schrader valve (bike air pump valve) that has a brass cap on it usually painted black. When you change your fuel filter without refilling with fuel, use the schrader valve to bleed the air out of the fuel rail.
1) Turn on the key and let the fuel pump prime.
2) After the fuel pump has cycled, use a rag and push lightly on the valve, remember the fuel pressure is at 32psi so it will spray pretty good if you push hard.
3) It will only take about 2 times of cycling and bleeding before you get straight fuel from the valve.
4) Replace the cap, clean yourself up and call it good.

[boatwakes]

Also, the computers are set up to run 87 octane and have a worse burn rate with anything else plus lotsa soot on the transom. Don't store your boat with fuel in it, it will absorb all the moisture in the air that it can. Keep it empty and fill when ready to use. THERE IS NO TREATMENT FOR ETHANOL REGARDLESS OF WHAT STA_BIL SAYS. Your fuel will loose octane after 30 days and by 90 days it's junk and shouldn't be run anyway.

[jake's02-22i]

Good to know. Thanks.