Fueling & Injection - Burned Up my inline Walbro 255 in about a month... Fully sealed fuel system to blame?

i have a inline walbro 255 on my lq4 setup, im getting all the symptoms of my fuel pump going bad (not to mention the loud whine)

i was thinking how could have my fuel pump have gone bad so fast? and i got to thinking... my fuel tank/fuel system is fully sealed(non-vented) + i would go a week or so before i would even open up gas cap, how was my fuel pump breathing while sucking fuel?

did the non-vented system create a increasing vacuum it had to fight against/ultimately ruining it?

No vent, and fuel being used = vacuum being created at the inlet of the pump. Do this long enuf, the pump will cavitate and STB.
Pulling a vacuum at the pump inlet, will cause air bubbles to implode in the pump.[Noise and erosion of components]
Fuel will boil at a lower temp in a vacuum. [More problems]

VENT THE TANK............

thanks for the reply! im def going to drill a hole in my cap and install a sealed 90 elbow onto it(can push on and off every time i need to take off my cap). that elbow will be running to a tube with a small filter at the end. hopefully that will solve the problem + i ordered a new walbro inline 255 from summit(this way i know its genuine)

if this is in your 65 chevelle , the factory caps should be vented , if you are using a sealed cap , then you have the wrong cap on it

if this is in your 65 chevelle , the factory caps should be vented , if you are using a sealed cap , then you have the wrong cap on it

it's a sealed cap from what i can see(no vented markings - just a high pressure warning), gotta love california... i cant even buy any vented ones locally.

i try to get a picture of the one i have right now up tomorrow.

try OPG and see if they have one , my 68 elco is a cali vehicle and has a vented cap , sealed started a couple years after , when the fuel evap systems came out

i bought my vented cap at pepboys or track auto , but that was many moons ago

i installed a new fuel pump(walbro gsl392 255) just like the one i took out. the one i had was so loud in comparison to this one, i can barely even hear the new one prime. i made a few small holes in the existing cap i had as a fix until i can figure out something more permanent.

how would you guys recommend going about venting the tank other than purchasing a vented cap(thinking it should be a fairly large vent hole[half the size of a dime or so]?) due to the ~70gph pump and expanding/heated fuel being returned from the engine bay.

the only idea i can think of as stated earlier is to drop the tank, drill a hole into the top of the filler neck, and have that routed to a tube a few feet long(into the trunk?) with a small filter mounted to the end for good measure. anything else i could do? or will the holes in my cap be good enough?