Water heater won’t stay lit with hatch door shut

Older furnace, only thing I can think of is adjusting the air gap sleeve.
Unless exhaust port being blocked misaligned?

I’ll give that a shot tomorrow. It’s a brand new unit that I just fired up this week for the first time after installing a couple of months ago.
The exhaust port is aligned fine so I don’t think it’s that.
Edited to add:
I got curious and just ran out to test again. I had installed a piece of window screen in front of the exhaust prevent mud dauber wasps from coming in and building nests. After removing it and trying to water heater again, it fired right up and stay lit. Turns out the window screen was enough deflection/baffle to choke off the oxygen and lead to a build up of exhaust.
Thanks for the suggestion to check!

Never mind

Seminoe Joe wrote:
I had installed a piece of window screen in front of the exhaust prevent mud dauber wasps from coming in and building nests. After removing it and trying to water heater again, it fired right up and stay lit. Turns out the window screen was enough deflection/baffle to choke off the oxygen and lead to a build up of exhaust.

We use these -- Screens

They do a good job without interfering with any burners. They come in many different sizes. We use them on the hot water heater and furnace.

Looks interesting. I’ll just stick with my window screen patch and remove it when I need to fire up the heater though.