Genset running out of fuel

[MyPleasure]

Hi fellas, I’ve been having problems with my genset running out of fuel after running for a while. when I switch positions on the fuel tank selector switch, the generator will run for a while, and run out of fuel again. I’ve removed all the fuel supply lines and they’re all fine, no restrictions or loose hose clamps. I replaced the generator fuel pump, checked all the fuel filters, etc.. I’m wondering if the problem could be the tank selection switch itself? Has anyone had a problem with the switch restricting the flow of fuel?
Thanks for your help again!

[waybomb]

Where is the anti siphon valve for the genny? I'd inspect it.

[g36]

What is run for "awhile"? 1-5 minutes 10 minutes or? How about connecting a temp fuel line to a external gas tank such as a outboard motor tank etc and see what happens.

[buster53]

Not sure I’m following what you are telling us. Generally, gensets only draw from one tank. Are you saying you have a switch to draw from either? I have that for my main engines, but not my genset.
Also, the pick up tubes for the genset are shorter than the main engine pickup, to keep you from running the tank empty just running the genset. I used to have a Carver 3807 that needed at least 1/3 tank in order to run the genset. Once the fuel got down to that level, it could no longer get fuel and shut down.

[MyPleasure]

Hi, sorry, I should have been more specific about run times. The genset will run for maybe 10-20 minutes just fine, then it will just quit from lack of fuel. My fuel tanks are always full when we head out, so I know that it’s not lack of fuel. Our boat does have a switch (valve) for running off of both port and starboard fuel tanks, but it’s marked with the port tank as the preffered tank. I don’t know if this switch was installed at the time of build, or afterwards. When the genset stalls, I can turn the switch a quarter turn, and the genset will run for another 10-20 minutes and stall out again.
I’m just wondering if there’s a problem with the switch itself? Could it be gummed up with old fuel? I guess I’ll try removing the switch and see if it has any fuel buildup or something.

[bud37]

Source of the post I’m just wondering if there’s a problem with the switch itself? Could it be gummed up with old fuel?

That is certainly possible, take it apart and inspect the valves as a first check.

[MyPleasure]

I see that there is a kind of packing nut on the top of the valve. If this nut has come a bit loose from whatever reason, it could allow air to seep into the valve and maybe create a kind of airlock that prevents the fuel pump from pulling fuel into the genset.
This is all theory, but I can’t think of any other reason that the generator is being starved of fuel. First thing I’ll try is tightening the packing nut, but I’m going to pick up a new valve (switch) in case.
Thank you guys for your help!

[Midnightsun]

It would be helpful if you posted a picture of this valve you have so we can offer some better advice. Sure sounds like an unusual setup.

[bud37]

Are your fuel lines to the valving from the tanks all dedicated to the generator ?
Do you pull from one tank or the other or are the lines teed into the engine feed lines somewhere ?

Air infiltration can be an issue , I have experienced that before especially when the generator feed line is not dedicated and it pulls fuel from the other unit attached depending on how the lines are run.

Yes, I agree a pic would be good, I like the 1/4 turn full flow ball type, not a fan of fuel valves with packing.

[MyPleasure]

The generator fuel line is definitely teed into the main engine fuel lines, I think that this is a factory install. I’m not worried about the generator using the main engine fuel because I never let my fuel tanks get below 3/4 full anyway.
There are 3 fuel selector valves in the fuel system with one for each engine and its corresponding fuel tank, and then they are teed to a separate valve which supplies fuel to the generator. It looks like I can switch each engine to run off of either fuel tank.
I will take some pictures of the setup next time I’m at the boat.