I am thinking 5psi... does that make sense? I would have to look in the book for our 1910. Why don't you just add the open tank lid indicators, I am sure there must be a kit to retro-fit for the 1900 cart? Mind you ours doesnt work now... worked fine last spring, cleaned the whole drill/tank & blew air into some of those small hoses & well now it don't work anymore. JD techs cant seem to figure that one out, they say it is a very simple system to figure & can't find any crimped hoses anywhere, which is usually the culprit.

 I am sure that Glensts would probably have the correct answer for the psi in the tank... he's helped me out before with some advice for the 1820/1910 setup.

David