Replaced cap and rotor, motor won't start

lushka16

Seaman Apprentice
Joined
Jan 21, 2004
Messages
34
I bought this cap and rotor and installed it today. My engine is a 1988 4.3LX Merc.

Yesterday my boat ran, today it will not start. I can hear that there is compression, and the smell of gas leads me to believe that gas is being injected, and seeing as I worked on the ignition system, I suspect no spark.

I'm 99.98% certain that I put the rotor on correctly, and I'm 100% certain that I put the cap and wires on correctly.

What kind of tests can I do to track down the problem? Are there any rookie mistakes that I could have made to cause such an issue?
 

Reel Poor

Vice Admiral
Joined
Jan 29, 2005
Messages
5,522
Re: Replaced cap and rotor, motor won't start

Make sure the blades on the interupter didn't hit the sensor in the distributor. Check for spark from coil. Check for voltage to coil positive terminal with key on.
 

lushka16

Seaman Apprentice
Joined
Jan 21, 2004
Messages
34
Re: Replaced cap and rotor, motor won't start

Can you give details (or a link) on those procedures?
 

jimbresee

Cadet
Joined
Jul 6, 2006
Messages
16
Re: Replaced cap and rotor, motor won't start

I've been 100% certain about my wires before, and after checking everything else realized I had them wrong....

To check if you are getting any spark at all, you could ground a plug, or pick up one of those cheap in-line spark testers from autozone...

Good luck and let us know what you find!
 

Rob454

Chief Petty Officer
Joined
Oct 9, 2005
Messages
508
Re: Replaced cap and rotor, motor won't start

Make sure the coil wire is on all the way. on my boat the plug wires look like they are on but you need to hear/feel them SNAP into place otherwise they look liek theire on but theire not making contact
Rob
 

lushka16

Seaman Apprentice
Joined
Jan 21, 2004
Messages
34
Re: Replaced cap and rotor, motor won't start

The coil wire is definitely on, that's the first thing I checked. I ought to change out the wires anyway, is there an automotive equivalent, or do I need to get marine ones?
 

Reel Poor

Vice Admiral
Joined
Jan 29, 2005
Messages
5,522
Re: Replaced cap and rotor, motor won't start

If you remove the coil wire from the distributor cap and tie/hold it about a 1/4to 1/2 inch away from a good clean ground you should be able to see a spark arch from the wire while cranking the engine.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,581
Re: Replaced cap and rotor, motor won't start

Put your old rotor and/or cap back on and then replace one thing at a time.
 
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