Re: 2000 mercruiser 350 horizon no start
I have no detailed info on the efi setup. But at first blush I'd check to see if there are any breakers tripped. If so why?
If you get your ear or some kind of stethoscope onto the pump you can listen to see if there's any sound when you power it up. The pump could be stuck/seized. If you can hear something happen when you apply power try giving the pump a couple of raps to see if starts to turn.
Those things don't stay fixed though, if it stuck this time it probably will stick again.
I disconnect the battery, remove and replace electrical connector plugs in situations like that. Plus snug up electrical grounds and look for corrosion around them. Corrosion causes breaks in electrical connections. When you do that check for green contacts, green ain't good. You can clean em up, but don't go too aggressively, the copper wiring and contacts in boats is tinned to reduce corrosion. Just remove enough of the corrosion to start a shine on the metal. And if you find crunchy wire change it.
People who know more than me will be along with better diagnostic information. Maybe some tests you can do with a meter instead of needing the high dollar scanner.
Keep watching, and good luck.
