So here is the story: I have a 2008 formula 353 with twin 525 efi. The one motor stopped running, and wouldn't start up again. My vessel view came up with a code crank/cam sensor. Because it wouldn't fire, I assumed it was the crank sensor. I bought a new crank sensor through gm. It still wouldn't fire. So I moved the crank sensor and cam sensor from the good motor to the bad motor. Fired up and ran at idle for about 5 minutes. I turned it off, celebrated, and started to clean up. Then I tried to start again, wouldn't fire. I took the crank and cam sensor from the bad motor and put it in the good motor, fired right up, multiple times.
Any ideas?
I have heard that those sensors are on a 5 volt reference loop. A friend of mine, with an 8.1 suburban, had a similar problem that was throwing a crank sensor warning, but it turned out to be another sensor on that same 5 volt loop.
HELP!!!! Thanks

On our 525 boat the oil drive / cam sensor was the problem. Sometimes the crank sensor shows up because of a no start or slow start condition. Have you scanned with a Rinda? If you want to stay on top of your 525s get one. It will save you time and money.

What I would like is to get is my hands on a wiring diagram. Yes, the sensors are mercury,

first and foremost you need to post your engine serial numbers.

Early 525 where set up differently than later ones for a jist of info. This all goes by engine serial numbers - year model means nothing for marine engine apps.

Also there is issues with the wiring harness per certain engine serial number segments

OM959462 bad one, OM959462 good one

Haha 2 engines with the same serial number. Oh I do not miss to much.

OM959835 good one. The problem is eating dinner after 13 hr work day and typing.

The saga continues. I put the computer from the good motor on to the bad motor, it fired up and ran. Then after starting 3 more times, it wouldn't start. Put the computer back on the good motor, it worked fine. Checked fuel pressure, ok. Next check firing of plugs .

Well you proved it’s not the computer then. The Rinda will help you narrrow it down. The smart craft doesn’t always point to the exact problem/sensor.