Fuel Suction Line Strainer in Tank - What I found

[Jon W]

I've been talking about the engine harness upgrade lately, but today was check whether the in line fuel strainer in the fuel tank was there. I thought I'd pass on what I learned today in case you haven't checked for it and are wondering whether you should. The Critical Upgrade says it's to remove the strainer to avoid clogging and unplanned engine shutdown. In my case I've run across two other reasons. One more critical than the other.

The suction tube line is threaded into a tank flange on top of the tank. The OD of the hose on the tube is slightly smaller than the ID of the tank flange. The beckson port above the tank does not line up with the suction line.  To get the line out of the tank I had to take it out on an angle. As luck would have it, the hose fell off into the tank. I then removed the tank level float switch to try to get. Looking forward see 1st picture – the suction port is on the right and the float switch is on the left.

After a few hours of fishing blind, I found a couple of presents in the tank from a previous PO.  I retrieved an old level float switch and a small plastic tube. No idea what the small tube was for. The old level switch could interfere with the working level switch at low tank levels. See 2nd picture

I kept fishing and was finally able to get the hose. One end was severely split open (no strainer). So I turned it around and pushed the not split end onto the suction line. I reinstalled the level switch. When I went to reinstall the suction line, the other end of the hose had split open in that short amount of time. Now neither hose end would work. The hose is a seamed hose and the failure is on the seam. Hard to tell, but see 3rd picture

This is why I'm passing this on. You may not have any fuel concerns, but the hose may be dissolving and fall off with no warning. You think you have fuel, but no fuel can be drawn because the tube suction is now above the fuel level.

This must be a special hose (½" ID and looks like 5/8" OD). I can't find one at WM or SD Marine Exchange. So far Auto parts stores haven't had submersible hoses. The hard tube section of the suction line appears to be ½" copper. If I can't find a hose, I may see if a ½" tube coupling will fit on the suction line. Then sweat/solder the OEM tube to flexible copper tube to get the length back. If you know where I can get the correct size submersible hose, or a better idea on how to fix this, please I'm all ears.  Jon W.

[Mike and Joanne Stimmler]

Jon,
There is a Universal Engine parts distributer on Rosecrans and Shelter Island DRIVE AND ALSO A Yanmar dealer on Shelter Island Drive on the left before you get to the Island and yet another place to try fairly close to the Red Sail restaurant. Try these out.

Mike

[Jon W]

Thanks Mike. SD Marine Exchange is the one by Red Sails and they had 1/2" line, but the OD was too large. I'll try the other two places and hope for the best.  Jon W.

[Ron Hill]

Jon W : That's good info you posted, because most C34 fuel pickup tubes are smaller in diameter and you can slide on a short section (3/4 inches) of 3/8" fuel hose to lie on the fuel tank bottom. 

[Jon W]

3/8" hose on a 3/8" rigid tube matches the rest of the fuel system and makes the most sense. Maybe a previous PO changed it to 1/2" or it came that way from the factory. Either way it's a problem.   Jon W.

[Jon W]

No luck finding a hose to fit onto the original 1/2 inch OD tube and fit thru the 1/2 inch NPT tank flange. So I replaced the original ~ 8 inch long tube with a longer SST tube welded to the nut with an angle cut at the other end. When installed, the lowest point is ~ 3/4 inch above the bottom of tank, and the top of the angle cut is ~ 1 inch above the bottom. Fuel is drawn sideways not vertically. This should leave only ~ 1 1/2 gals of fuel in the tank the pump can't get.

I used a 5/16 inch dowel as a story pole to measure the depth from bottom of tank to the top of the tank flange and to mark the fuel level. The fuel level mark was used for a rough validation of the accuracy of the fuel gauge in the cockpit. See photo of tube and story pole. (The measurement reflects what I guessed as worst case thread make-up. In reality more threads were showing so the ~3/4 inch gap to the bottom).

Ran the engine for ~ ½ hour at various rpm's with fast and slow speed increases/decreases. No problems so far.

Now back to the electrical. Jon W.

[Stu Jackson]

Congratulations, good work.   

Now's the time to start a fuel log.   

[Ken Juul]

I don't like friction fits.  Last time I had my fuel pickup tube out I put a couple zip ties on to ensure the hose stays on the end of the tube.

[Ron Hill]

Jon : Apparently you haven't read the Mainsheet tech note articles and the frequent posts on the pickup tube.  There is a reason that the pickup tube is a couple of 3 inches off the tank bottom with a flexible hose attached !!!

That reason is so the flexible hose turns and lays on the bottom.  That bent hose allows it to always sucks in the bottom fuel along with any bottom junk/stuff/critters that grow in the fuel and let the Racor filter that stuff out!! Helps keep the tank cleaner.

A thought

[Jon W]

Hi Ron,
   I read your 1996 article, and many, many posts on the pick up tube and screen before starting.

   My original pick-up tube ended about 4 " above the bottom of the tank, not 2-3". The original hose did not reach the tank bottom (my story pole confirmed that). My hose indicated that it was likely to leak air into the system at ¼ tank. Extending the new pick-up tube without a hose to within ¾" of the bottom and cutting on an angle should provide adequate laminar flow along the bottom to pick up the junk/critters to send to the Racor before the pump. Lots of variables here, but my thought was less parts, less risk. Wrote on the side of the tank the screen was removed.   Jon W.

[Ron Hill]

Jon : Now I understand your problem. 

When you slide a 1/2" ID fuel hose on to a 1/2" OD pickup tube that hose on the tube will not fit thru a 1/2" hole!!  Daaaa on my part!   

You've got the best solution given the circumstances.