Older mercury 3.0 suddenly won't start

[trooper1954]

Hi all,

Brought my SeaRay 160 to the dock to replace a tach. Did the replacement, and now the boat fires up for a second but does immediately.
Thinking it had something to do with the tach wiring, I completely disconnected the new tach....but still the same problem.
Any help or troubleshooting tips would be appreciated
Thanks

 

[alldodge]

Disconnect the gray tach wire at the negative side of the coil and see if it continues to run

 

[trooper1954]

Thx alldodge,
I took the grey wire off of the right hand post in this photo....that is the coil, correct? Made no difference...fires up for split second, then dies.

 

[trooper1954]

Can't seem to attach the photo....any tips?

 

[trooper1954]

[No message]

 

[alldodge]

Might be just coincidence that it started this after the tach replacement.

Place a voltmeter on the plus side of the coil and see if your loosing power when it dies

 

[Faztbullet]

Left a purple wire off on the tach...

 

[trooper1954]

alldodge...will check that today.
Faztbullet....not sure I understand this....the tach at the moment is totally disconnected, and the engine starting problem persists. Don't think it's anything to do with the tach.
Thx.

 

[Faztbullet]

All the purples have to be tied together..thats the 12v back to coil from switch.

 

[trooper1954]

Faztbullet,
Thank you for making it more clear...so if I understand correctly, the purple wire that should go to the tach needs to be connected to the purple wire from the ignition switch to enable the boat to start? Thanks for your patience....I'm not that mechanically minded, and appreciate the help

 

[alldodge]

to enable the boat to start?

No, 12V from the purple wire on the ignition switch is connected to every gauge and the coil. The purple wire powers all the gauges and the motor. The key switch turns power ON but if a gauge is not connected the motor will start, just the gauge will not work

Need to know if your loosing power to the coil. No power to the coil, motor stops

 

[Faztbullet]

Faztbullet,
Thank you for making it more clear...so if I understand correctly, the purple wire that should go to the tach needs to be connected to the purple wire from the ignition switch to enable the boat to start? Thanks for your patience....I'm not that mechanically minded, and appreciate the help

Yes....

 

[trooper1954]

Thanks guys....but now I'm totally confused
One of you said yes, and the other no??
At present the wires for the tach are loose and marked, under the dash but nothing is connected.
Surely if the purple wires need to be connected, the motor would not turn over with the ignition key.....but it does.
Thx again for your patience.

 

[alldodge]

Fazt is correct IF the purple is daisy chained at the Tach. In the pic below it does show where its daisy chained at the tach but for me that would be a unnecessary failure point. Most would splice and then run to each gauge

 

[trooper1954]

Thanks to both of you.,..decided to bite the bullet and get a tech....coming tomorrow at 10. Will let you know what the outcome is.
Thx

 

[trooper1954]

Hi all,
Boat now running fine, idle was set too low, needed new plugs and a distributor cap, and the coil was being robbed of power somewhere...I didn't really get what the tech said.
Tach now running perfectly so all is good....thanks to all for the help.