Crank but want start Mercruiser 5.7

Wellcraft1996

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Jun 23, 2021
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31
Engine was running but running rough so I had fuel tank cleaned and put new fuel in tank. Then had carb. rebuilt and reinstalled carb. then it would not start. Checked for spark at plugs and there is no spark. Replaced sensor in distributer and still no spark. Replace ignition coil even though coil showed 1. 6 reading on multimeter. Changed distributer cap and still no start.
Please help
 

Bondo

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Ayuh,...... Welcome Aboard,...... What vintage is it,..??
A serial number would be even better,......
 

Wellcraft1996

Seaman Apprentice
Joined
Jun 23, 2021
Messages
31
Ayuh,...... Welcome Aboard,...... What vintage is it,..??
A serial number would be even better,......
Good Morn. My boat is a 1995 Wellcraft Excel 26 . Well the engine cover has the engine serial number as OF414565 but I'm not sure that's the correct serial number, do to the seller stating the engine was replaced in 2011 with a new engine. The original owner passed away and left it with his son. He didn't no much about the history of the boat. When I purchased it it ran but ran rough. So I changed oil, plugs, distributer cap, rotor wheel and sensor along with a new ignition coil. Still ran rough, So after checking the fuel I discovered a good amount of water in gas tank. Had gas tank drained and cleaned and tank had some sludge in it as well so it was recommended that the carburetor be rebuilt.
I re installing carburetor after rebuild and then it would not start. Just crank and crank no start. First thing I checked was for spark at the plugs and their was no spark. I tested the coil the best way I knew with a multimeter and got a read of 1.6 and 7.9, So this is the point I am stumped with this engine. Also I discovered yesterday the emergency cut off button may be bad do to the instrument gauges stop working, could that be cause of no spark at the plugs?
What do you think?
 

alldodge

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Mar 8, 2009
Messages
42,537
The serial number shows TB4 ignition
Run thru the troubleshooting guide (the TB4 and TB5 are the same)
TBV Troubleshooting.jpg
 

poconojoe

Lieutenant Commander
Joined
Sep 10, 2010
Messages
1,966
Go through that troubleshooting flow chart in post #4, it is an invaluable tool.

My emergency lanyard switch once got accidentally tripped without my knowledge.
The engine would crank and hiccup like it was almost going to start.
 

nola mike

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Apr 22, 2009
Messages
5,407
. Also I discovered yesterday the emergency cut off button may be bad do to the instrument gauges stop working, could that be cause of no spark at the plugs?
What do you think?
No, but a bad ignition switch can do that. Do you have 12v at the coil pos with the IGN on?
 

Wellcraft1996

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Jun 23, 2021
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31
No I don't have 12 v at the coil. I need to recheck to be sure but I don't think I do. The batteries are fully charged
 

Wellcraft1996

Seaman Apprentice
Joined
Jun 23, 2021
Messages
31
Go through that troubleshooting flow chart in post #4, it is an invaluable tool.

My emergency lanyard switch once got accidentally tripped without my knowledge.
The engine would crank and hiccup like it was almost going to start.
Ok will do
 

boblane

Cadet
Joined
Jun 27, 2016
Messages
7
Engine was running but running rough so I had fuel tank cleaned and put new fuel in tank. Then had carb. rebuilt and reinstalled carb. then it would not start. Checked for spark at plugs and there is no spark. Replaced sensor in distributer and still no spark. Replace ignition coil even though coil showed 1. 6 reading on multimeter. Changed distributer cap and still no start.
Please help
I had same problem tried everything then I unplugged the wiring harness and cleaned pins and pow! it works
 

Wellcraft1996

Seaman Apprentice
Joined
Jun 23, 2021
Messages
31
I had same problem tried everything then I unplugged the wiring harness and cleaned pins and pow! it works
Checked the wiring harness connectors they didnt seem to be corroded but I use sand paper to clean up a little but still no 12 volts at the coil.
 
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