OK, here goes...
I am having problems filling up my fuel tank. It only takes about 3-4 gallons before it starts to burp and overflow the fill line. I did a bit of research on these forums and other places as well. It seems as if the likely culprit is a clogged fuel vent line.
This is permanent below deck fuel tank. I have a 1990 Glastron Sierra 175 with a new 4.3LX Mercruiser (4 bbl w/ Vortex heads) and an Alpha One sterndrive.
Here is what I have done so far:
1. Removed the vent line from the back of the fitting on the transom. Blew into the hose, felt resistance, but air eventually flowed and I could hear bubbles in the fuel tank. This did not correct the problem.
2. Removed the fitting in the transom and checked for debris or clogging. The mesh screen is intact and clear of debris. The fitting has no other noticeable clogging. Blowing into this shows no resistance.
3. I checked to see if the fuel vent line had any loops or dips in it that might cause fuel to buildup in the line. The fuel line runs straight (horizontal) across the top of the fuel tank due to the design of the tank and surrounding structures. The line then turns straight up towards the transom vent fitting. No noticeable dips, at least nothing drastic.
4. I removed the entire vent line hose. (this was no easy task). The hose had no debris or clogging. Air blew through just fine.
The only thing left is the vent fitting on the top of the tank. I believe, the only other possible location for a clog. The fitting looks like a small square block with a right angle penetration into the top of the tank. I tried to remove the fitting. There is a hex nut between the square block and the tank. The hex nut comes off easily, however the fitting does not slide out after loosening the hex nut. Is the fitting supposed to be removable?
Do these tank vent fittings have check valves? Could this be the source of the clog? How can I tell if this has a check valve? Should I try to remove this fitting again?
I did try to push a coat hanger down the fitting and into the tank. The wire went all the way inside the tank. But still did not fix the problem.
I am stumped here. I can post pictures if needed.
Thanks for any help.
I am having problems filling up my fuel tank. It only takes about 3-4 gallons before it starts to burp and overflow the fill line. I did a bit of research on these forums and other places as well. It seems as if the likely culprit is a clogged fuel vent line.
This is permanent below deck fuel tank. I have a 1990 Glastron Sierra 175 with a new 4.3LX Mercruiser (4 bbl w/ Vortex heads) and an Alpha One sterndrive.
Here is what I have done so far:
1. Removed the vent line from the back of the fitting on the transom. Blew into the hose, felt resistance, but air eventually flowed and I could hear bubbles in the fuel tank. This did not correct the problem.
2. Removed the fitting in the transom and checked for debris or clogging. The mesh screen is intact and clear of debris. The fitting has no other noticeable clogging. Blowing into this shows no resistance.
3. I checked to see if the fuel vent line had any loops or dips in it that might cause fuel to buildup in the line. The fuel line runs straight (horizontal) across the top of the fuel tank due to the design of the tank and surrounding structures. The line then turns straight up towards the transom vent fitting. No noticeable dips, at least nothing drastic.
4. I removed the entire vent line hose. (this was no easy task). The hose had no debris or clogging. Air blew through just fine.
The only thing left is the vent fitting on the top of the tank. I believe, the only other possible location for a clog. The fitting looks like a small square block with a right angle penetration into the top of the tank. I tried to remove the fitting. There is a hex nut between the square block and the tank. The hex nut comes off easily, however the fitting does not slide out after loosening the hex nut. Is the fitting supposed to be removable?
Do these tank vent fittings have check valves? Could this be the source of the clog? How can I tell if this has a check valve? Should I try to remove this fitting again?
I did try to push a coat hanger down the fitting and into the tank. The wire went all the way inside the tank. But still did not fix the problem.
I am stumped here. I can post pictures if needed.
Thanks for any help.
