Better Fuel Tank?

[prjacobs]

I'm running a Yanmar 2GM20F and have been troubled by air in my fuel lines, causing poor power and stalling. In the past I've had trouble with leaky lift pumps so I removed the lift pump and connected a small Facet electronic pump in line between the CAV primary filter and the small engine-mounted filter. This makes bleeding the system after filter changes very easy, and it also eliminated the old lift pump from letting air into the system.

However, I'm still occasionally getting air into my fuel lines, and I suspect it happens in rough water when the tank is less than half full. With the wedge-shaped design, and being very flat, I suspect the fuel sloshes around enough to leave the inlet pipe uncovered for brief periods. Has anyone else experienced this problem?

My old Albin Vega had a 30 litre cylindrical tank under the starboard cockpit combing, by the locker lid, that made the journey for fuel work by gravity only, and I never EVER had to bleed air from the system. (It also had a Yanmar 2GM20F.)

Has anyone on the forum installed a different tank?
If so, where did you put it and how much capacity does it have?
I'm quite happy with the present tank's capacity, but can't risk letting the level drop below half

TIA for any help!

[aemilia3]

Are you sure it is due to trapped air? I had the same symptoms as described by you. However I found later out the problem was diesel bug blocking the fuel line in the fueltank. I solved it by removing the fuel tank from my boat and clean it by flushing with water. A lot of dirty/gelly stuff came out and after drying the tank out completely, reinstalled it back onboard Aemilia. Ever since I am using the Mr. Funnel fuel funnel/filter system which seems to work quite well. Maybe it is worth reading the article I posted on my website.

http://aemilia.org/Albin_Ballad_978_Aem ... _Fuel.html

Hope this will be of any help.

Beste regards
Frans van der Wel
Aemilia - B978
http://www.aemilia.org

[MarkRyan1981]

Another thing to watch out for if it IS air and you can confirm this by bleeding that air back out again, is to replace the fuel lines. If they are old and brittle, the smallest of microscopic crack will introduce air into the line. May be worth replacing them as a matter of course if they are old...?

[prjacobs]

Thanks for the suggestions guys. I use a biocide in my fuel, and a West Marine funnel filter when filling. The boat has only been in the water for 30 months since a TOTAL restoration. Fuel tank was boiled out at a radiator repair shop, all fuel lines and fittings replaced, new filter housings, new injectors, new, new, new ... $$$
Last year I removed the tank again to check for dirt/bugs, it was clean as a whistle. I also vacuum tested all fuel lines individually, then as a complete system, had the injector pump rebuilt (it came back with a hand written note attached "The pump was not the problem". Oh well, at least I know it's in good shape now.
All the steel fuel lines on the engine were replaced after discovering a crack in a line, hidden by a metal clamp on the engine block, that would let the engine run until it warmed up enough to open the crack and let air in.
I'm hanging on to the sloshing fuel theory as it's all I've got right now

[MarkRyan1981]

Does the problem go away once you have bled the system again on the engine (until the next time)? What primary fuel filter have you got? Possibly a problem with that?

I've been in some really rough stuff, at alarming angles, with the standard tank less than half full... and my 2GM20 (not F!) has been solid and has never had air in the lines (and frankly, with my old fuel pipes, mine deserves to be knackered - yup, one of my next jobs to do)...

Nasty old fuel lines:


Tank:

[prjacobs]

Yes, it goes away until the next instance of low fuel level and rough seas. My CAV filter sits up above the tank, and I'm wondering if this may be a problem, although I can't find any logic as to why it doesn't work.
I'll take some pictures of my setup when I go down to the boat this afternoon (to finish waxing the hull ). Maybe you can spot something obvious that I'm missing ... later.

[MarkRyan1981]

Does it happen more on one tack or another if motor sailing? I'd have a look at the fuel intake and make sure it is low enough down in the tank so it is drawing fuel out of the very bottom of the tank. Is it all the original tank fittings or did you replace in your great rebuild?

The very worst time for the engine to stop working is rough seas stuff of nightmares if crossing a bar etc.

[prjacobs]

Mark, thanks for your input.
All the tank fittings were copied as per the old ones. A later modification put the fuel pickup a bit closer to the very bottom corner, but this did not have any effect, good or bad. The idea was to limit the amount of space water could accumulate, and have it pulled into the sight glass on the filter if any was getting picked up, rather than leaving too much of a dead zone at the tank bottom for black crud to grow in. You guessed it ... another theory!
Usually when sailing enough to heel the boat I'll shut the engine off, to prevent oil in the sump from sloshing clear of the pickup, or having the cooling water inlet exposed to the breeze ... just my OCD way of doing things I guess
Here are some pics of my fuel system:

This shot is looking forward at the aft side of the galley bulkhead showing the filter location. The original layout had the filter in the aft port side of the engine compartment. The good was that it was lower than the tank top, the bad was that changing the filter was a difficult job at best.


This shot is looking down at the top of the tank showing fuel line layout.


This shot is at the rear starboard corner of the engine box showing the Facet 40288 electric fuel pump.


This is a shot of the front of the engine.


The lines are:
1 shut off valve to filter
2 filter to pump
3 pump to 2nd filter
(All the above lines are 5/16" flexible rubber.)
4 braided steel/rubber line (new) from 2nd filter to injector pump.
5 Two steel lines (new) from injector pump to injectors.

Tomorrow morning we're heading out for a couple of days. Tomorrow promises 12 to 15 knot winds, but Saturday looks pretty calm, so we'll get another chance to come up with some more theories!

[prjacobs]

Ran 5 continuous hours at cruising speed, calm seas, full tank, didn't miss a beat!

[MarkRyan1981]

Any re-occurrences Peter?