Bertram31.com General Bulletin Board

Air in fuel system

Posted By: JoeF
Date: Tuesday, 12 April 2005, at 11:12 p.m.

Ok - the first step is to admit it...i'm stumped.

I've got an air problem with the fuel system in my CAT 3208Ts and need some thoughts. My engines draw fuel from the main tank under the cockpit deck. The fuel passes through a Racor 900 filter, then through a flowscan fuel meter sensor, then into the engine mounted fuel filter...then into the injection pump, then the return line takes the unused fuel back to the tank. If my fuel tank falls below 1/4 full and i shut my engines down for any more than a minute or two, i have trouble getting them started...i need to go down and use the manual push-pull lever on the lift pump to get things going again.

I also notice that when changing racor filters, the fuel does not always come to the top of the filter housing...on a different boat that i owned, as soon as i loosened the lid on those filters fuel would start to pour out.

Obviously have a leak somwhere. Both engines have the same disease, but the port has it a little worse.

I tried tightening every fitting on the system, checked every inch of the fuel hose. I also ran a test for leaks...i closed the main fuel shutoff vales located on the main tank. Then i went to the engine lift pump and manually started pumping. I watched the cool little vacuum guages on the racors until the needle just hit the yellow area. Then i fetched and drank a beer. I came back after the beer and noted that the needles were still on the yellow line. So i deduce from this that there is no leak between the tank shutoff and the engine. (this eliminates the racors, a shutoff valve just before the racor, the flowscan sensor and the engine mounted fuel filter as leak suspects).

But now i'm stumped. I suspect that fuel could be draining from the return lines somehow. I mean, the tank is located lower than the engine and the return fittings in the tank do not go all the way to the bottom (i'm picturing them going down only as far as the 1/4full level inside the tank) fuel could drain from the return side right? Maybe?

So what i'm hoping someone can suggest is some sure fire way of testing for this leak.

I've lived with this for a few years now. Its just buggin the crap out of me.

I'm beggin here...someone have an idea?

Joe

Messages In This Thread

Air in fuel system
JoeF -- Tuesday, 12 April 2005, at 11:12 p.m.

Re: Air in fuel system
Ken Ching -- Tuesday, 12 April 2005, at 11:51 p.m.

Re: Air in fuel system
Vic Roy -- Wednesday, 13 April 2005, at 8:42 a.m.

Re: Air in fuel system
bruce -- Wednesday, 13 April 2005, at 5:19 p.m.

Re: Air in fuel system
Vic Roy -- Wednesday, 13 April 2005, at 7:11 p.m.

Re: Air in fuel system
Capt. Mike Holmes -- Wednesday, 13 April 2005, at 9:16 p.m.