4.3 lfx no start

[Keharris51]

Hey all, thanks for taking the time to read and potentially help. My engine cranks, but won't fire. I replaced the cap, rotor, new plus wires, and plugs. Ignition coil, and the sensor in the cap. I'm out of ideas. Any diagnostic help would be appreciated. Thank you.

 

[alldodge]

Howdy

How about giving us a tad bit more info about what your working on and when it started these issues.

Got a year, an engine serial number is best?
How long have you had the boat?
When did the current trouble start?

 

[Keharris51]

Sorry, the year is 96 merccruiser 4.3 lfx. In a 88checkmate starlet. I've replaced most of the mechanical parts, and cooling system parts within the last few weeks. The boat sank last year, no engine damage but everything else pretty much had to be replaced. Yesterday I was cruising down the lake, and the boat shut off, and wouldn't start. .

 

[Fun Times]

Does your tachometer seem to go up during engine cranking to say around 300 RPM?

Also sometimes an internally shorted tachometer will prevent the engine from starting/having spark....Do you have spark coming out of the coil and spark going to the spark plugs through the plug wires?

As a test, try removing the gray wire from the tachometer gauge and see if it will start or/and spark.

Also be sure the mercruiser shift interrupter switch on the shift cable plate mounted on the engine isn't stuck/engaged... http://www.bing.com/images/search?q=mercruiser+shift+interrupter+switch&FORM=HDRSC2

 

[Keharris51]

thank you for the reply, I only had a few minutes today to do some tests, tomorrow I can thoroughly go through it. The tach does not go up when i crank it.

 

[alldodge]

You should have a TB-5 but may be a TB-5 ingnition. Suggest running thru the troubleshooting chart. The chart works for both