Bicycle air pump

I saw a way in a video to check the check valve of the fuel pump without taking down the tank. Guage and airpump. Pressurize the line and if it drops the problem is in the tank. whT do you think of this method? Do yall think that there are any flaws in thjs testing method?

You can use that method combined with a cheap ultrasonic leak detector.

You can use bike pump for a cooling system pressure test also --- all you need is to McGyver an adaptor such as a selection of suitable T pieces and hose reducers.
Pressure testing a cooling system when cold is the best way of finding leaks for really small one use it with UV dye and torch.

I now have a Chinese made Cooling system pressure testing kit --- didn't cost much and works great.