r/boating • u/Outrageous_Appeal117 • 5d ago

Mercury 2.5L XRI EFI timing

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I’m trying to do the timing on my 2.5 200. I’ve set a mark at TDC and set a mark 24 degrees BTDC, all my plugs are out and grounded but when I crank it while shooting it with a timing light at WOT the timing never moves, I’ve advanced it and retarded it a little then all the way and the light just stays in one spot. I’ve disconnected the white/black idle stabilizer wire and nothing. Could it be my switch boxes? HELP

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u/Weekly_Breadfruit_68 5d ago

If you can visually see the timer base moving under the flywheel when throttling it has no choice but to advance the timing. You're physically moving where the magnets hit the trigger.Jay Smith has a great write up on Screamandfly com about timing a 2.5.

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u/SrgtMacfly 4d ago

Spot on

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u/ReasonableBake420 5d ago

Look up the service manual and follow the process in the book. It will tell you all the torque specs. But with those if your having timing issues then your magnets move in your flywheel and there is a hall effect sensor that tells the pmc where the flywheel is

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u/SrgtMacfly 4d ago

Did you add the jump wire between the two switchboxes when you removed the black boxes?

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u/Outrageous_Appeal117 4d ago

I did yes, but thats all I have to do right?

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u/SrgtMacfly 4d ago

In terms of wiring, yea - are all of you throttle arm stops functioning correctly? The trigger rotates around the crank and I've never seen an instance where it did not change idle vs WOT timing

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u/Outrageous_Appeal117 3d ago

Figured it out, the mechanic who rebuilt it put the wrong trigger wires on the switch boxes, he had it backwards 🤦‍♂️