Hi guys I'm new here so really don't know how things work around here but I'm here to seek advice & help . I own a 3tj its a beautifull bike runs super smooth or should I say was running super smooth . I took my bike for long ride it was fine I got home parked it of . Next morning it wouldn't start with out a boost while riding it just loses power completely & it won't start . I took it to a workshop they replaced the regulator but it still does the same . Please help

How much experience of bikes do you have ???

It could be a few different things so before we suggest lots of things we need to know some other symptoms.
Are the headlights dim or does the rev counter stop working before / as the bike dies. If so suspect the charging system (the alternator) or the battery.
Because you took it to a garage I'd assume they checked the battery, but then again what they did hasn't cured it. I think maybe the alternator isn't charging the battery. When you bump the bike it's running on the charge left in the battery until that flats completely.

So you need a voltmeter and a bike battery charger, then charge the battery overnight.

Welcome to the forum.

Thank you very much. I suspect the generator coil but I will do as you said & keep u informd. Thank u

No worries - we like pictures

if the battery charges ok off a charger and holds the charge then i'd also check all the connectors, first before i condemned the genny, sounds like it could be the genny, but they aint cheep even used

whip off the genny cover (LH engine case) and give it a good visual inspection, then follow the wires back checking all connector blocks as you go, any showing signs of corrosion, give em a good clean

to test the genny you want this manual
FZR400SP1991_3TJ-ME1.PDF
from here
http://www.commline.com/FZR/400/MANUAL/
you can test the genny by following the troubleshooting guide in section L9

edit: we do like pics

i got the genny coils if you need them, pm me!