F30 won't run on aft tanks.

TJWells · Post by **TJWells** » Tue Jun 21, 2011 6:53 pm

Hello,
I need some help with my f30, I've owned her since 2003. When we took her out for sea trials we took a short trip on the front tanks(2 60gal galvanized) when I switch to the rear. the engines shut down as it runs out of fuel. The fuel seperators (Racor) are full. The bowls have no dirt whatsoever in them. when I change over to the rear tanks the bowls eventually start getting bubbles in them like its pulling air. but the seperators are vacuum locked. I don't believe the tanks are rusted badly inside but I've been wrong before. If the pickups are getting clogged, I would believe I'd see something in the filters or bowls. Has anyone had problems with the anti siphoning valves like this? Give me a clue. I really don't want to pull the tanks but the situation could be worse(Front tanks!)

prowlersfish · Post by **prowlersfish** » Tue Jun 21, 2011 8:00 pm

anti siphoning valves , plugged vents , plugged p/up tube would be a good place to start . bace fuel hoses sucking air the valves on the tanks are open right ?

Stripermann2 · Post by **Stripermann2** » Tue Jun 21, 2011 9:51 pm

Like Paul said. Clean anti syphon valves also be sure to close valves off from tanks you don't want to draw from. If you run from rear tanks, shut off front, you want to run from a single tank, shut off other 3. But money is on anti syphon valves. They may start engines and rev up fine but under load, they will restrict fuel volume to where engines will shut down.

TJWells · Post by **TJWells** » Tue Jun 21, 2011 10:42 pm

Thanks for the quick replies. I always isolated the tanks with valves. so as not to pull fuel or air from forward tanks. I used compressed air to blow through vent tubes and feed tubes. I don't believe the copper lines are the problem. Originally the pick up tube was loose on the fitting going into the tank. BTW where the heck can you get those pick up hoses with the pipe fitting attached at? Last time I tried looking in the tankks I didn't see anything but I was looking through a 3/8 npt hole. The fuel line goes into a vacuum almost immediately. the pick up tubes have no strainers and have been replaced already. If I have that much rust in my tanks why don't I see dirt in my filters or seperators. Could it be that my fuel pumps are too weak to overcome the anti siphoning valve? Sorry for all the ranting but I love this boat and havent had enough confidence to take it out for a long trip since i've had it.

TJWells · Post by **TJWells** » Tue Jun 21, 2011 10:48 pm

I really lean toward tha anti syphon valves because of the way it just plugs up instantly and goes into a vacuum. Is there any more info on those particular valves that trojan used. Mine jjust had a loose check ball.
I was expecting a spring or something.

k9th · Post by **k9th** » Wed Jun 22, 2011 5:39 am

Welcome aboard. Clogged anti-siphons will cause that for sure.

g36 · Post by **g36** » Wed Jun 22, 2011 6:58 am

anti siphon valves
you can check with bob at beacon for them or i just replaced mine and if you email me i can tell you where i purchased them. dont know if i would get in trouble for posting it

does it look like the piece in the middle of the pieces?
http://www.marineengine.com/boat-forum/ ... 13&thumb=1

Stripermann2 · Post by **Stripermann2** » Wed Jun 22, 2011 7:37 am

"Could it be that my fuel pumps are too weak to overcome the anti siphoning valve? "

Not likely, if that were the case, the they wouldn't be able to draw from the front tanks. The valves become clogged and stick. THEN the fuel pumps can't draw against the valve. The valve should be located at the top of the tank, between the fuel line and tank inlet. If you do a search on the forum, you'll find many posts on the subject.

Good luck.

TJWells · Post by **TJWells** » Wed Jun 22, 2011 11:44 am

yeah they look like that. last time I took them out which was a while ago. but then they were loose and did the same thing they do now. This happened to me on the water I kept opening the seperators to let air in to get back to the dock. What a day that was!