Fuel pick up tube and air in the system

[thaeni]

While motor sailing my diesel stopped running. I checked the primary filter
and found quite a few pieces of gunk but the fuel bowl was full of diesel
and the filter was clean.
I checked the secondary filter and it was clean and the bowl was full of
diesel. I assume what happened was my fuel tank is full of gunk and
my fuel pick up tube has a screen and a large piece blocked the flow
and sucked air into the system. When I bleed the air out all was OK.
Not sure where the air came from as I had a full tank.. My questions
are:
1. any ideas where the air came from?
2. when I get my tank cleaned should I have the yard remove the
screen?

 

[navigator97]

The general consensus is that the screen does more harm than good. Having the yard pump out all the fuel, cleaning the tank, filtering you old fuel (called "polishing the fuel"), and returning the fuel to the tank should solve you problem, at least in the short run. I always some Microbcide to all tank fill ups to take care of any critters that develop in the fuel and water interface (if any water is there from condensation). The air might be leaking in from old hoses that are breaking down. If old, it would be a good time to replace all the fuel hoses (supply and return).

 

[gpdno]

For awhile I was getting air in my system also. Ended up replacing the old cracked fuel line with new line and the problem is gone. I suspect you might have a small crack that's letting air seep in.

 

[captainpat]

PROBLEM: CONTAMINATED FUEL. I picked up a load of bad fuel in Killkenny Creek, GA when I returned from FL with my 35.5. It took me two seasons and a lot of anxiety with engine shut downs (of course at the worst possible time) before I finally solved the problem. Naturally the cause was the bad fuel, but the real culprit was the screen on the fuel tank pick-up tube. It would clog with junk and prevent fuel from flowing, causing an air block once the fuel in the lines was consumed. I drained the tank several times and got a LOT of crap out, thinking that the problem was resolved. NOT SO!!! The tank was contaminated so the gunk kept returning. The additive caused everything to settle to the tank blottom - waiting for rough conditions to be stirred up and clog the screen again. Water in the tank made things worse with algea growth.

SOLUTION: Inspect/Change the O-ring on the fuel fill cap to help keep water out. Install a good additive at shock dosage, let it run through your fuel system, then let sit in the tank for a day or so. Pump the fuel and garbage out of the tank. Discard the fuel - or have it polished! REMOVE THE SCREEN FROM THE PICK UP TUBE. (When mine came out you couldn't even see though it when held up to a light!) Install clean fuel. Let your primary filter do the job it is intended for. It is a lot easier to change the primary filter then to deal with a clogged pick-up tube.

ALSO RECOMMENDED; consider changing to the Racor 500 series turbo filter. It is much easier to change the element of that filter, even in bad conditions.

After accomplishing everything above I never had the problem return during the next five years of owning that boat. FYI: I would make it a point to change the Racor fuel filter at every oil change. Cheap linsurance.