Mercury 5.7 EFI

[STEVEO1962]

Hi can someone please help l have a Mercury 5.7 efi and it turns over fine but will only start when l connect a jump pack l have fitted new batteries and it still will only run when l connect a jump pack
Thanks Steve

 

[alldodge]

Remove both Pos and Neg cables at both ends. Don't just let the Neg cable block end go, remove it. Then clean to shinny metal on the ends and reinstall