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exclamation Fuel Filling Issue (colinambler)
Posted: 2:03:51 pm on 7/25/2012 Modified: Never
I am the new (3 months) owner of a Mark V with inboard diesel Yanmar 1GM.  The gas gauge is non-functional from previous owner, so we've been conscious to monitor fuel usage.  However,  when attempting to re-fill, we cannot reach full capacity.  After 1 gallon (or less) has been poured, a backup occurs and fuel begins flowing out from the fill port.  My initial thought is that symptoms suggest there is some type of air pocket, kink in the line or ventilation issue that is preventing the fuel from entering the tank.  But after troubleshooting 'the obvious', we can't notice any visual indicators.

About a week ago, the tank went dry.  We had to re-fill (only the small amount of fuel the tank would accept), bleed the engine and then get back to harbor.  Essentially, we're operating on a 1-2 gallon tank.  We'd love the comfort of full capacity!  Especially if god forbid we got into a sticky situation.

Any ideas?

Colin Ambler
C&C 27 Mark V
Chicago, Illinois

  Re: Fuel Filling Issue (Steve Reid)
Posted: 7:08:46 pm on 7/25/2012 Modified: Never
I'd check the vent hose to make sure some sort of critters (spiders, wasps etc.) haven't taken up residence in the vent hose.
You can access the hose by getting doww inside the seat locker, locate the hose and follow it up to where it connects to the thru hull fitting. Remove the hose clamps and remove the hose from the fitting. open the fuel fill deck fitting and blow into the vent hose, you should be able to easily blow thru the hose. also try blowing thru the thru hul fitting it should also be clear.

Steve Reid
Still Knot Working Mk V #75
  Re: Fuel Filling Issue (colinambler)
Posted: 7:30:06 pm on 7/25/2012 Modified: Never
Hmmm.  We do have a ongoing spider issue that we're burning to eliminate, so your diagnosis a strong possibility.  I will investigate and update with my findings.

However, devils advocate: would a nesting explain why the tank accepts a small dose of fuel, but then acts as if it's full?  If the vent line were clogged, my guess would be that it wouldn't accept any fuel from the start.

Anyways, this seems like a great suggestion that I'm hoping does the trick.   With a bit of tinkering and exploring, I'm confident I could locate the tube and perform the check.  But I'm not familiar with this type of engine or the fuel system, and it's always nice to eliminate a few rounds of trial / error when possible.  Would you mind providing some more details on the location of the ventilation tube or perhaps a picture / diagram?  

PS - what's the best way to exterminate the infestation of spiders??  They haven't got into the cabin much, but within a day or two of cleaning, they're all over the deck / hull!

Your help and insight is much appreciated.  Thanks!

Colin Ambler
C&C 27 Mark V
Chicago, Illinois

  Re: Fuel Filling Issue (oasis)
Posted: 7:01:13 pm on 7/26/2012 Modified: Never
My first bet would be Steve's idea.  But my second suggestion would be to check the fill hose - not likely to have a kink, but could be an internal delamination and collapse?  Might let a little fuel through slowly?  Just a guess, but....

Barry   Oasis, 1987 Mk V
  Re: Fuel Filling Issue (ALAN FORD)
Posted: 9:48:38 pm on 7/27/2012 Modified: Never
Colin, a holding tank needs a vent line because the pump moves the waste into it and the displaced air must escape or the tank will become pressurized . ( I had this problem a few weeks ago and Steve's suggestion of dead hornets and their nest in the outside of the through hull fitting was the cause).
In the case of the fuel tank the displaced air as you fill it can escape around the filler nozzle, as it does with a car. I suspect that the vent is needed to allow air IN to the tank as you consume the fuel.
If this reasoning is more or less correct then your problem might be more to do with the line itself, starting from the filler cap on the sloping surface, starboard side aft of your Mk V, to the point where it connects to the tank. Have you tried pushing a half inch plastic hose  through the line to see if there is a physical blockage in the line? Or, as suggested, has the hose collapsed? Perhaps the small amount of fuel you can get in to the tank is actually the capacity of the line, which very slowly bleeds in to the tank?
If you climb into the cockpit locker and contort yourself a bit you can reach and examine these lines quite well.
Keep us all posted please.

Alan of SMOKE 1984 Mk V 002

  Re: Fuel Filling Issue (Steve Reid)
Posted: 4:55:10 pm on 7/27/2012 Modified: Never
The fill for your tank is on the sloping deck on the starboard side of the cockpit, the vent outlet is on the starboard side of the hull just under the deck joint flange and directly abeam of the filler fitting. Given that you boat may have been laid up for some time before you purchasd it and if the tank was not completelt full, when she was originally laid up. If that was the case and if the vent was plugged during that time, expansion and contraction due to temperature changes may have caused the fill hose to collapse.
You can inspect the fill line and vent line hoses by entering the cockpit storage hatch (seat hatch) on the starboard side of your boat. You need to orient yourself so that you are facing aft, you should be able to easily locate the 2 hoses and follow them from the deck/hull, as the case applies, all the way along to the tank. If the hoses appear to be in good shape, not kinked or collapsed, then you can try inserting a electricians fish wire down the hoses from the deck or hull.
The fuel tank on the Mark V is stainless steel so there is much chance of delamination as was suggested by a previous poster. However if the fuel that was in the tank, didn't have a good quantity of fuel stabilizer in it, when the boat was laid up and if it's been laid up for a long period of time it is conceivable that the fuel has solidified or gelled, if that's the case then the tank will have to be removed and professionally cleaned out. Not a nice job, but the good news is that you can then replace the fuel gauge sending unite.

Steve Reid
Still Knot Working
  Re: Fuel Filling Issue (Hardlee)
Posted: 8:03:30 pm on 8/8/2012 Modified: Never
Hello Colin

I hope you get the vent working on your tank so you can get fuel into
the tank.  I have a new to me Mark V built in Rhode Island and the gauge was not functioning.  I found a form-fit&function replacement and installed it by getting to the top of the tank via the seat locker.  

The tank on my boat came with a full tank as I discovered by removing the old gauge and sticking a tape measure down inside the tank.  I haven't yet had to fill it.  However, if you can get fuel into the tank by filling it very slowly, that would indicate a blockage in the air vent. You might even notice air bubbles trying to escape as you fill slowly to prevent back ups.   I'd also wonder if the Yanmar would run properly due to no air intake?  The engine itself runs with its own close loop system by to pipes going to and from the engine.  That means you should see three ports on the top of your tank.  The vent exits out the stern at the starboard side of the transom.  You should see a brass fitting or the tubing under the seat going back to that area from the tank.  Make sure the tube is clear and the part that goes down inside the tank should bubble if you blow into the tube.  

I replaced my fuel level system with a plug and play replacement. In fact, I removed the hing with the float components from the new assembly and put them on the shorter support taken out of my tank.  The hole pattern seal at the top of both are identical.  Google search with this part number:  

Fuel Sender
Code F
P/N 90424P, 240 - 33 ohm  4-24" max tank depth

Manufactured by
Veethree Elec. & Marine LLC

Although listed through many suppliers you can get it
via E-Bay, there are others who stock it.  

I have only used a quarter tank since early June even though the engine has been used for about 30 hours at 2500 rpm.

Please feel free to ask questions

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Fuel Filling Issue (colinambler)
Posted: 9:46:14 pm on 8/10/2012 Modified: Never
Hey John,

Great response!  We got the fuel filling issue resolved---I think there was small snag or clog with the vent tube.  Disassembly, clean, and reassembly seemed to do the trick.  We'll see if the issue reoccurs.  

But more related, how did you know our fuel level gage was broken too?!?!  Ironically, I just ordered the same part to do the repair as you mentioned in your post.  I'm not sure the issue lies in the sending unit or the gauge.  So I ordered both, and will either return the unneeded part or replace while I have the system apart.

Do you have any advice / tips / instructions for the job?  I'll be starting early next week.  I've been traveling, so haven't had a good opportunity to look at the mechanics and assembly of the system---I'll be going in cold.

Thanks again,

Colin Ambler
C&C 27 Mark V
Chicago, Illinois

  Re: Fuel Filling Issue (davidww1)
Posted: 1:51:36 pm on 8/10/2012 Modified: 1:54:39 pm on 8/10/2012
I have been given to understand that many types of gauges are paired, even if not sold together, and it's good practice to replace the sender and the receiver/dial together, both from the same manufacturer. The sender has a particular pattern of screw holes for attaching it to the tank; if the holes don't match, don't assume you have the wrong model - just turn the unit 180 degrees.

Spiders, like "the poor" will be with you always. One way of eliminating them (and wasps) from your boat is to hang a Vapona strip (a dichlorvos insecticidal strip that looks like a 9 x 3 inch piece of rubbery plastic) in the boat. This at least ensures that there aren't any bugs in the boat for spiders to catch, so they won't stay there. Put the strip in a ziplock back before spending more than five or ten minutes below - it's not really toxic, but it's not good to breathe too much of it.

David Weatherston
Towser, Toronto
C&C 27 Mk IV

  Re: Fuel Filling Issue (Hardlee)
Posted: 7:17:40 pm on 8/10/2012 Modified: Never

I'd take the components off the new float fuel sensor and remount them on the old support that sticks down inside the tank.  First recheck the top flange with the mounting holes to make sure it's all still free of any cracks etc.  Once you have the assembly ready to go down inside the tank, I'd switch on the engine key and run the float arm up and down outside the tank to make sure you see the needle changing as it should with different arc angles between the float and the support arm.  

When you tank out the old unit be sure to note the orientation of the float inside.  You should make sure you place the float arm in the same direction.  

I did all that and my gauge works great.  

Good Luck

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Fuel Filling Issue (surfj24)
Posted: 5:14:07 pm on 8/12/2012 Modified: Never
All VERY GOOD STUFF!!  But remember, always make sure to top-off your diesel tank after your fuel gauge pulls away from full.  We don't want condensation to be another factor in this problem.
  Re: Fuel Filling Issue (colinambler)
Posted: 10:10:57 am on 8/15/2012 Modified: Never
Thanks guys!  I received the gauge, sending unit and have other needed supplies on-hand.  I read through the directions for the sending unit and understand the procedure.  I'm going to attempt the job today or tomorrow.  Will post pictures and results afterwards.

Still one question though.  The sending unit (as gathered from instructions) seems very specific towards measurements; both related to the vertical placement of the arm, and length of the flotation device fixed to the arm.  All specifications are based around the dimensions of the tank.  

Does anyone have insight to this process and/or the measurements of the fuel tank on the Mark V so that I prepare the unit beforehand?  It'd be great to have it adjusted to the correct specs before going down under the deck box.

Colin Ambler
C&C 27 Mark V
Chicago, Illinois

  Re: Fuel Filling Issue (Hardlee)
Posted: 10:36:46 pm on 8/16/2012 Modified: Never

I don't recall the exact dimensions of the tank but
it shouldn't matter as long as you cut the arm length to
match the one you remove from the tank.  And, you orient
the arm in the same direction as the one you remove.  If you
don't follow those two details, it's possible the new unit will
get hung up inside the tank and not read over the full range of
fuel levels.  Also you must make the new support extrusion mounted
from the top flange the same length as the old one you are replacing.

If you do this you should not have any problem.  I just did mine this
way about two months ago and it's working well.  I also tested it before
placing it inside the tank.  That was done by turning on
the ignition with the two wires hooked up and swinging the arm by hand
to see the fuel meter deflect up and down from full to empty.

Good luck

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine