I have an American Standard pull out single handle kitchen faucet that suddenly lost water pressure for both hot and cold water. I removed the spray assembly and saw a large amount of debris in the inlet screen. After cleaning it out and running the faucet without the re-attaching the spray assembly with the intent to flush out any out other loose debris in spray hose. After a few minutes I re-attached the spray assembly hand tight and still noticed low pressure. Apparently more debris was in the inlet screen. I discovered the water pressure is fine (for now) when I re-attached the spray assembly a little less than hand tight and no visible signs of leaks from the spray assembly. After running the water a few minutes with the good water pressure, I hand tightened the spray assembly again resulting in low pressure and debris in the inlet screen. What could be causing the debris, that resembles ground black pepper flakes? Is it the over tightening or a symptom of something else? I also replaced the cartridge in the faucet handle just in case and tried the hand tight spray assembly. It still resulted in low pressure and debris in the inlet screen.

Over tightening not likely the problem.
Are you on a municipal water system or a well?
Remove aerator at other faucets and inspect for similar debris?

Is this faucet and new installation? Back to you, Tom

Harold: I'm on municipal water system. I'll have to check the other faucet aerators later tonight. I would not expect to see the same debris since the water pressure in the other faucets are fine.

speedball1: It is not a new installation. It was already part of the house when I purchased it two years ago and the house is 10 years old.

suddenly lost water pressure for both hot and cold are you saying that not only the sprayer but also the spout lost pressure?
Is the faucet working now in the sprayer isn't it? Can you describe the debris? Is the "sprayer hose clear now, but to sprayer still had debris? Back to you, Tom

The more accurate description should have been "suddenly sever low water pressure for both hot and cold". Water still comes out, but a very low pressure. The amount of water almost looks as if the faucet valve was opened less than a quarter (more than a trickle of water) even thought the faucet valve is fully open.

When I remove the spray assembly and have the faucet valve fully open, the water pressure from the spray hose is greater than when the spray assembly is attached. The debris I see in the spray assembly inlet screen looks like small black flakes. When I turn on the water, with the spray assembly removed, initially some black flakes come out of the hose then the water clears up.

When the water clears up, I removed the debris from the spray assembly inlet screen and reattached the assembly to the hose. As long as I tighten the assembly, not using that much force, to the point where I do not see leaks the spray is functioning as expected when the faucet value is fully open. From this point it looks like I can cause the spray assemble to re-clog if I hand tighten the spray assembly more to the spray hose.

Update: I got home an noticed less water coming from the kitchen faucet again when the valve is fully open, so I had to clear the inlet filter in the spray assembly again. I looked at the other faucet aerators, some had a tiny bit of debris (small black specs) but definitely not as much as what is in the kitchen faucet. The kitchen faucet is closest to the water heater so I'm thinking it could be debris from the water heater? So I will try to flush the water heater this weekend.

I bought this house 1 year and 9 months ago and I never flushed the water heater since I bought it. I'm not sure if the previous owner(s) ever flushed the water heater since it was built. It's now 10 years old. Any tips on flushing a gas water heater as if it has never been flushed for 10 years?

Connect a garden hose to the drain valve, put other end of hose in sink, a floor drain or outside. Open drain valve and let water run until clear.

Suggest you clear kitchen faucet spray. Open cold water only and let it run for a period of time. Open spray again to see if any debris has accumulated. Repeat for hot side. Then flush water heater and repeat process to determine if water heater is the problem.