No gas to carb every week

Once gas gets to my engines all is fine, they run good and will restart easily for a day or so. But the longer between starts say the next week, there is no gas in the fuel lines, and I risk draining batteries to pull the gas from the tank if at all. A little carb cleaner down the throat or a squirt of gas fires them up for a whole but takes a bit of it to pull the gass thru the lines. Where does the gas go that is left in the lines?
Twin 1978 mercruser 120's plus a generator in an 1978 houseboat, all on the same one tank feed line, thru a new anti siphon valve, a water seperator, then split to the three engines. All new hoses 4ft from the seperator to the closest two and about a 7 foot hose to the starboard engine. The separator stays full, but the clear fuel in-line filters that show gas moving thru when running and are mostly full when the engines are shut down, are dry the next week. Drained the tanks and refilled with fresh gas.
Even though old, all three fuel pumps shouldn't fail together? Two summers ago, I just had to pump the carbs a couple of times and they both started fairly well and always better the shorter the time between runs, but even after a week off only maybe 6 pumps and a 20 sec crank.
Where to look next?

Re: No gas to carb every week

You should never have 3 engines hooked up to a single fuel pickup to start with. Do you pump the throttles at all when starting after a few days of sitting? May take 2 or 3 pumps.

Re: No gas to carb every week

Your fuel pumps should hold the pressure. You can verify with a guage. Ethanol might have eaten up your valves.

Re: No gas to carb every week

Sounds like the fuel bowl is draining slowly down the intake while it's sitting, causing the long cranking to get er running again.

Re: No gas to carb every week

Thanks all
Don- added shut off valves just past the separator this fall to isolate each engine line thinking one might be affecting the other and with no effect. A pump or two was normal a couple of years ago and still now after sitting an hour or two, but start with the same two and add a couple pumps to the count each day and another minute of grinding, to the point when I just went to the back, see that the clear in-line filter is dry and then give it a squirt by hand. Again once it fired and pulled fuel thru, was back to normal.

Scofflaw-Dont know that it ever had ethanol as it only get fuel from the docks and that should be no ethanol? I did run a fairly hevy load of SeaFoam for about a year, when I was not able to go out enough to keep the gas fresh. Is that stuff harmful along these lines? I have not tried a guage on the pump. Just attach it ahead of the pump, crank, and watch for lowering pressure? I will try that.

Eric - if this and I suspect something in this area at least partial cause, the first step is just a carb kit? I've never reuilt a carb but not afraid to try, just not eager to randomly take things apart without someone with some experience more than I suggesting it. Probably after 30+years it would not hurt to do it to one carb to start just on general principles. Cant go anywhere as it is and it would be a good excuse to spend another day at the lake. but again, what about the stuff sealed in the lines as showing at the in-line filter? If the fuel pump/carb wasn't sealing that could siphon back to the tank?

Would the daily changes in temp affect the fuel tank enough to draw the fuel back into the tank if both the carb and pump seals were leaking?

Re: No gas to carb every week

Rochester Quadrajets were famous for draining the fuel bowls into the intake after sitting for a while, causing exactly what you are seeing, and there was a "fix kit" for it to plug the areas where the bowl plugs leaked. Depending on the carb, a rebuild may be in your future. You may also need to adjust the choke on her too.

Re: No gas to carb every week

Here are a list of rebuild videos for you to check out:

http://forums.iboats.com/showthread.php?t=362542

Re: No gas to carb every week

Thanks again. I do remember seeing gas pooled down in the throats but thought I had just flooded it with the pumping. But maybe it was there before hand. I think the carb rebuild cant hurt would be a good winter project and after watching those videos the fear is gone. Will deal with the fuel pumps in spring if the carbs dont fix the problem.

Re: No gas to carb every week

Before you go taking anything apart , I would check and see if the choke plate is closing firmly on the top of the carb body . This is very important in starting a cold engine . Do this before taking the carb apart and throwing parts at it . When you look inside the carb and see fuel on the throttle plate , that means you do have fuel in the carb body .I have seen where some people have a bad " choke pull off " . This device opens the choke butterfly a bit so the engine will get through the warm up cycle while the choke is gradually opening When this component(choke pull off) goes afoul , people will bend on the choke linkage so the choke butterfly is partially open so the engine will not flood itself as soon as it starts