Checking out the screenshots of the program, they look very much like the program I was using. Thanks for the link.

Good Riding!
Jim

If you are tech savvy this will do most of the commands for the 15p and m variants and it comes with source code so it can be modded to fully support them. It also has support for the quirky 'K line' interface that our model uses.
http://sourceforge.net/projects/iaw-scan/
You will need to construct or buy the interface ($20 worth of components) to get it working but it may be worth a try if you are so inclined. Also it should be possible to contact the author and have him add the relevant commands/error code interpretation for the bike versions

hi, if you have a kill switch/button that rubber key goes into on the 400 just unplug the wires 2 wires that go to it this by passes the system or at least it does on my 450. one less thing to worry about in the wiring just primes up with ignition turned on.

It's running again
 

Thanks again for all your advice on this, but It's running again. I decided to just throw all the original equipment back in, including relay and ECU, and it fired right up. Don't ask me why, but I think it might have just been moisture in the ECU. After letting it sit in a cool dry space, case open, for about 3 months.

Hi Headhunter99

I've had the same issue on my 2004 fse 400 & after checking all the electrical connections I found a relay in the airbox compartment with severe corrosion on the contacts. After cleaning this its been fine I also managed to source one for ?6 on ebay (from a fiat punto of all things)

Unfortunately I have spoken too soon as after an hours ride the fault returned whilst riding up a steep hill, total loss of power & then unable to start / tickover. Can anyone help????

Any one out thier no were to get quick release fuel couplers for gasgas fse400 2002 both ends one on fuel lines and the other one for top of tank x2 of them thanks johnmc

In the US, I would call one of the more aggressively advertising GasGas parts dealers, such as Matto Cycles, or one of the longer term GasGas dealers that traditionally stocked a lot of parts, such as Halls Cycles.
If you can't get any good information from the above suggestioed sources, the former importer of GasGas motorcycles and parts, https://cpd.direct/ , might be able to assist you in your quest.