All I can ask is what is wrong with using good old Mr Gravity, after all he is the cause of it leaking now, why complicate matters?
Not a thing NormK as long it works. I was looking at the professional way of testing in a small shop setup. I now home repair techs don't always need things like this but the pump setup will have other uses so it not a dedicated setup. Most of us do have vehicles that this will one person repairs much easier too especially bleeding brake systems. Around here it can be hard to get someone to take time to help to bleed brakes. I personally did repairs for 3 years before getting the tool but it came to a point that I could no longer do without it.
It is just more control when using a air source as air will also seep better as liquid has more resistance. The problem is it can take longer to reveal leaks and if you gravity pressure is more then the pop off pressure it would defeat the purpose of the test. I even had leaks under air pressure that would stop for a short time when fuel was added to the system and would only leak over night when I was using the gravity supply tanks. With air pressure system with a gauge I have been find leaks within 30 minutes most times instead having to wait over night.
As I said the holding pressure is around 5-7 psi and most carbs will pop off around 10 psi. Also with pressure inline you can check for slow leaks as its reading will slowly over time. With a gravity it is possible to open the valve while testing and have the pressure to just stay just above the seal off pressure therefore leaking and giving a false indication of a problem.
Widget, What I am was referring as test equipment was not a pump for fuel but instead is a pump setup Similar to the MityVac MV8500 vacuum/pressure pump. It is the same setup that is use to test those small Walbro, Zama, and the like carburetors plus crankcases of many 2 cycles.
Mityvac MV8500 Now there are cheaper plastic versions than this metal one. Also be careful being lead a stray and getting a vacuum only version as you do want to get the combo unit. There are times that you can find a good deal on these but it takes time. Locally they were wanting close 100 usd for mine but I was able to find it online for 52 usd including shipping at the time I purchased my tester.
I did have a minor problem my unit when I got it as line adapters are molded and those area weren't as smooth as needed to seal well but that is an easy fix.
