mariner 50hp fourstroke

[650xs 2]

having trouble 50 hp four stroke mariner 2003 model efi can't seem to get my tecpro scanner to talk to it ,got all the rite bits plugs etc ,am i rite in thinking i need to plug in the dtt scanner but am told the new promo will cope ????......problem is engine runs fine then loses power dies down loses revs after run time of 2 mins to 20 mins .....we have not yet tested a great deal as want to see if its stored some faults ..feul pumps etc al good all basic stuff all normal ..bit of a puzzle
feel clean ,feel pump good poss loosing electrical .....ie weak spark poor signal from power pack signal from charge coil trigger ,net yet tested but on todos list as all hot and will connect test equipment later to see it do it poss etc ,history has done it before with a prevous owner .............??????
any suggestion ?....thank you
also want to get best lap top soft ware to cope with most makes outboards too any suggestions or hand held ...looked at rinda

 

[650xs 2]

more update ,,,,,,,,having trouble give it another goo.so i did and a result at last ,,trigger fault took a bit to get it rite thou...
at least his time no disturbances from customers .......shows fault on scanner not stored ....strange just gave me trigger fault x4 first time then test again run up to temp etc then is started again splutter ..i have still not yet crossed with a spark test at same time as customer came to stop me .....so more free time and report late ......