Zero turn head scratcher

[mrmowitallpa]

Gravely 460 Model: 992233 Zero Turn with a Kohler ECV749 EFI engine. The mower is stored in an enclosed trailer. Used 1-2 times per week for 7-8 hours total. I've been having an issue where I open the trailer after 5-6 days to start the mower on the first lawn on my route, and get a strong odor of fuel. It's clearly coming from this tank selector valve, which I've now replaced twice with an OEM Gravely part. I am certain that the fuel tank is not leaking, but it also appears to be splashing or spraying the tank from this valve, as evidenced by the fuel residue on the metal cover plate and tank. I replace the fuel filter annually during my late fall winterization process, and also replaced these clamps with fuel injection screw type band clamps.

Another strange issue is that ever summer in mid-late July (hottest here in PA), the fuel system does not supply fuel to the filter. Almost like it becomes air or vacuum locked. I run clear fuel filters, so I can physically see that there is no fuel getting to the filter. I then have to break it down in the field, reroute lines from this valve, directly from the tank to the filter.

I'm scratching my head at this point. What is going on here that I'm overlooking?

 

[Firebrick43]

Vent in the tanks cap bad at least with the fuel filter not filling problem. While running loosen the cap, and see if it starts to fill.

Very common problem.

Second is **** in the tank blocking the outlet. I have found leaves causing this issue 3 times over the years. It’s intermittent as it will get stuck over the outlet and then when it dies or is shut off the leaf floats away.

 

[Firebrick43]

Maybe with the fuel valve the have sourced ****? Try a different style/brand?

 

[gregs]

Verify that the separate vent valve in each tank is working correctly. Thats the valve in the top of the tank that vents it back into the engines vapor recovery system. One big problem is that people overfill the fuel tanks. There was a decal showing that your only supposed to fill the tank to an 1" below the filler neck. A lot of people stuff as much gas as they can get in there so they can run longer. The liquid fuel gets in the valve and doesnt allow it to vent correctly. So it can cause pressure to build up and also cause a vacuum "lock" that doesnt allow fuel to be drawn out. The fuel gets "thrown" up into the valve from sloshing on rough ground and also operating on slopes. Verify the plastic lines are also clear. I have seen some so bad that there was liquid fuel in the lines and had to be blown out as its only a "vapor" recovery system. It also looks like the tank is leaking from the upper threaded insert as its wet up pretty high for the valve to cause that. Also explains the constant smell. The last thing to look for is tiny holes in the fuel lines. You really have to look hard for them, sometimes there wet from fuel leaking and sometimes not and will cause a fuel draw problem. Those are caused by Camphor Shoot Borers in search of the ethanol in the fuel. If its stored inside an enclosed trailer its less likely thats the problem, mostly in equipment stored in open pole barns. They will also drill holes in the hard plastic fuel tanks as well. If its not any of that then its mostly the full moon on the second week of the month on a day with the letter d in it.

 

[Peter 212]

That strong gas smell when you open the trailer is EVAP system pressure building up too much. Check the vent line from the tank, is it clear and is the cap venting properly? That pressure could be pushing liquid fuel past the selector valve seals even if the valve is new.

 

[mrmowitallpa]

I've removed both of the vents at the top of each fuel tank. I was able to blow through them, so the vents are clear. I'll need to check the lines. I've run both of the tanks empty this past season, and there is no visible debris in the tanks.

 

[mrmowitallpa]

Verify that the separate vent valve in each tank is working correctly. Thats the valve in the top of the tank that vents it back into the engines vapor recovery system. One big problem is that people overfill the fuel tanks. There was a decal showing that your only supposed to fill the tank to an 1" below the filler neck. A lot of people stuff as much gas as they can get in there so they can run longer. The liquid fuel gets in the valve and doesnt allow it to vent correctly. So it can cause pressure to build up and also cause a vacuum "lock" that doesnt allow fuel to be drawn out. The fuel gets "thrown" up into the valve from sloshing on rough ground and also operating on slopes. Verify the plastic lines are also clear. I have seen some so bad that there was liquid fuel in the lines and had to be blown out as its only a "vapor" recovery system. It also looks like the tank is leaking from the upper threaded insert as its wet up pretty high for the valve to cause that. Also explains the constant smell. The last thing to look for is tiny holes in the fuel lines. You really have to look hard for them, sometimes there wet from fuel leaking and sometimes not and will cause a fuel draw problem. Those are caused by Camphor Shoot Borers in search of the ethanol in the fuel. If its stored inside an enclosed trailer its less likely thats the problem, mostly in equipment stored in open pole barns. They will also drill holes in the hard plastic fuel tanks as well. If its not any of that then its mostly the full moon on the second week of the month on a day with the letter d in it.

I do tend to fill the tanks to the tippy top. I'll take that into consideration when fueling up. The actual vents are clear, but I'll need to check the lines.

 

[Fav Onefour]

I do tend to fill the tanks to the tippy top. I'll take that into consideration when fueling up. The actual vents are clear, but I'll need to check the lines.

Do you do this before parking in the trailer?
If so, I'd suspect expanding fuel. Those vent valves are designed for vapor. Is it possible you have liquid getting to the vents?

 

[Youngandfree]

I do tend to fill the tanks to the tippy top. I'll take that into consideration when fueling up. The actual vents are clear, but I'll need to check the lines.

On scag mowers, they have a white sleeve in the filler neck, don't fill higher than the bottom of the sleeve. Otherwise it overflows into the vapor charcoal canisters. It's happened to me a couple times.