Help with 1984 Mercury 25XD

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BobW89

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Apr 7, 2013
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St. Louis, MO
Gents,

I've searched the web for answers and have been redirected to this site over & over. Any help or direction would be greatly appreciated.

I'm a new boater and just purchased the following rig:
1984 Mercury 25XD - 25hp, 2 cycle, electric start, jet drive.
1976 Lowe 1448
1971 Trailer.

All was in fair condition at a fair price. It ran rough at idle, ran hot and needed much work. So this is what I've done so far.

New starter & solenoid, new battery, rebuilt carb, new plugs, new impeller, new fuel lines, new steering cable & deep cleaned. I went to start her up after getting everything done and in place, and she would not start. The starter cranked fast, I could smell the fuel pumping in but it just wouldn't "catch". With this being my first boat, but having some mechanical knowledge, here is my best guess. I thought it was starving of fuel, but when I removed the new plugs, they smelled of fuel. The starter is moving so fast that I thought it was a compression issue. I will purchase I compression gauge later today and test that. My other thought was the ignition. Is this getting a spark? When the motor is turning over, I get a good stream of water from the pee valve. I had to take a step back and get a second opinion.

Any ideas on what I missed? With the motoring running when I bought it, and now not, it almost feels like I'm either overlooking something simple or it needs more work.

Please let me know if more information is needed.

Thank you all.

Bob
 
Today I narrowed down that compression is not the issue, 90 psi on both cyclinders. However, I am not getting fire at the plugs. Any help on troubleshooting the ignition system? Not really sure how to begin. I will do some reading tonight and post any process.
 
If you're not getting spark on either plug the first thing I would do is to disable or bypass the kill switch just in case it's faulty.
 
You were right on the money. I went through all of the ignition measurements and found all meter measurements (ohms) were in tolerance. I then went back to the wiring diagram and checked every wire and found the faulty switch.

I was able to get her started and now moving on to timing. Thank you for the assistance. For those that may have the same motor, I posted the ignition measurements below.

Ignition Test Readings
Stator Leads - Blk/Yel & Blk/Wht 3.1 to. 3.7, Reading 3.11k
Trigger Leads - 6.5 to 8.5, Reading 7.86
Coil Leads - Primary (+) to (-) zero 0.0, Reading 0.001
Coils Leads - Secondary (Between Coil tower & (+) &/or (-)) 8.5 to 12, Reading 8.77

Again, thanks for the pointer.

Bob
 

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