I have a 1999 310E with the 4045T, right at 4k hours. I've owned it since 3300 hours and it has been well maintained since being with me, no major issues. The machine started clogging fuel filters, had to replace them every 10 hours or close to that. Next was a hard/extended starting condition. I ended up replacing the lift pump and cutting the bottom of the fuel tank open to remove all the rust, replaced the pick up screen while in there. The machine starts and runs good now, fuel filter is staying clean but I've noticed the tank is under some extreme vacuum, even with a new fuel cap. I try to relieve the pressure after every use but need to find the issue. I'm keeping the tank full of fuel now to help with rust.. Thanks
Welcome to HEF 346ci2 ! Did someone sell you non-vented cap by mistake?
Either that or the vent is plugged on the one he has. It is a very common malady with fuel caps. Some caps I have seen plugged, had very tiny openings in them. Some of them can be taken apart and cleaned.
Thanks for the welcome, looks like a nice place yall have here. I thought it came from JD but could have been aftermarket. The old cap didn't have a vent which I thought was odd, I will order another one from JD and go from there.
You cannot go wrong with an OEM cap. And, welcome to HEF !
Forgot to attach what was in the tank, check yours if you are killing fuel filters!