Bobcat T550 fuel return line grommet pops out

[tjstj]

I have a T550 that I bought at 700hrs. I noticed water in the fuel after draining a little off the fuel filter as part of a routine checkup at 750 hours. Started looking for a leak and found the fuel return line grommet was sitting out of it's hole into the fuel tank, allowing water to enter. I pressed the line and grommet back in but soon after running and checking it, the grommet was back out. I went to bobcat dealer and bought a new grommet for that application and installed it. Few weeks of use and it was back to the same issue: The new one was popping out now. It pops out while the machine is running. I can put it back in, start and run the machine and then check it and it will be out. But it doesn't happen every time. There have also been a good few times that I've parked the machine and it's been in and when I come back days later it will be out.
Is there a vent that is clogged causing too much pressure? Could it be the fuel cap? The fuel cap doesn't seem to be vented, but it's clean without any gunk or buildup.
Or is there a better way to get the grommet to stay in?

Any help or suggestions would be appreciated!!

 

[Vetech63]

It should be vented by a external vent or through the fuel tank cap

 

[tjstj]

From further research I found that excessive positive fuel tank pressure likely means exhaust gases are being pushed past the copper washer at the bottom of an injector, leading to pressure buildup of exhaust gases in the tank. Is there a way to test if that is the case, or to specifically find which is the culprit without removing all of them?

 

[Vetech63]

From further research I found that excessive positive fuel tank pressure likely means exhaust gases are being pushed past the copper washer at the bottom of an injector, leading to pressure buildup of exhaust gases in the tank. Is there a way to test if that is the case, or to specifically find which is the culprit without removing all of them?

Thats unlikely that I know of. Compression would have to get by the injector needle valve to get into the fuel system. Going by the copper Compression washer will come up the side of the injector and puff air outside of that injector.

 

[tjstj]

Maybe that was just for an older style injector. It seemed a possibility on older diesel trucks.

I will replace the grommet again, as well as the fuel cap. From the parts diagram, I do not see any vents to speak of.

Considering the water and dirt that got in, I replaced the fuel filter with a bobcat OEM, but would there be a recommended way to clean out the fuel tank?

 

[IceHole]

Id try to Run it with the fuel cap loose, see if it still happens

 

[tjstj]

The grommet stays in when I run it with the fuel cap loose, as the positive pressure does not build up to pop the grommet out.

 

[Vetech63]

Its probably a vented fuel cap. If its not it should be.

 

[ozarkag]

As Vetech says,
The fuel tank vent hose comes up to the filler neck just below the cap. Someone likely used an aftermarket non vented cap

 

[tjstj]

I picked up an new grommet and fuel cap. After comparing, the existing cap was not vented. I ran the machine for about 8 hours this weekend with no issues - new grommet stayed in place while using the new cap.

Looking like it's resolved - Thanks for the replies!