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Mercury 175 electricla problems

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prushworth

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" I have a 1979 175 Mercury en

" I have a 1979 175 Mercury engine. I have spent several hours testing the stator, trigger, rectifier, ignition coils etc. to no avail. I have no spark whatsoever. When cranking the engine the stator gives up to 110 vac, however the trigger gives no ac voltage. The stator does not give the same voltage ouput on all wires is this normal? According to the tests in the engine manual both stator and trigger should be OK. According to the manual the rectifier seems to be defective. Could this affect the voltage coming out of the stator or trigger? Do you know what voltage should come out of the trigger assembly when engine is cranking? I have tried technical service at Mercury and all that they have given me so far is what is in the engine manual. My local dealer can't understand the problem either. From what I have seen in the answers you have given others you seem to understand these sytems better than anybody else I have tried to contact. Your help would be greatly appreciated.

Thanks,

Phil "
 
"Phil... I'm uncertain if

"Phil... I'm uncertain if your message is directed at me or not. If so, you may have read in previous posts that Mercurys are not my line of expertise. However, if the charging rectifier has failed, there is no way that the voltage/current flowing from the charging stator can reach the battery. In which case, the voltage would back up at the stator resulting in a overheated stator that would crack and melt down. When this happens, there is a voltage drop in the area of the stator that would normally supply ac voltage to the power pack(s)... in short, there would not be enough voltage to energize the p/pack. I'd suggest looking under the flywheel at that stator to see if it's cracked, melted in any way, etc. Hopefully one of the Mercury techs here will jump in with more specific information.

Joe
"
 
" Thanks Joe,

I sent the me

" Thanks Joe,

I sent the message to anyone who could help me. I just rebuilt my engine the top bearing on my crankshaft was in dire straits so I had to open the engine and change all the gaskets and seals while it was on my workbench. I inspected the stator before installing it and it had no external damge that I could see. The problem that I encounter is that I can not restart my engine since I have reassembled all of the components. The trigger is brand new a Mercury original part. The old one was replaced because the linkage was in bad shape. Electrically it was fine. Any other suggestions?

Once again, thanks for your help this discussion board is great!

Phil "
 
"Phil,

You should start by

"Phil,

You should start by checking the cut-off circuit which disables the ignition first.

The ignition switch grounds one of the terminals on the switchboxes when it is in the off position. Also, you should have a mercury switch in this circuit which prevents the engine from being started accidently when it is in the up position. It is located just forward of the switchboxes, and a little higher. It might be malfunctioning.

Disconnect the wires at the switchboxes ( I think they should be black and yellow ), and see if you have spark. If you do then you know that there is a problem in the the cut-off circuit.

You won't get a true reading from the trigger coil with an ordinary voltmeter. You would need a peak reading voltmeter. You can use the milliampere scale on a simple voltmeter. With the red lead on a trigger terminal on the switchbox and the black lead on ground you should notice a fluctuation of the needle if the trigger is working when you crank the engine.

Check the voltage at the switchboxes from the stator. Each switchbox has a red and a blue wire from the switchbox. Check the voltage for each one while cranking.

"
 
" Tony,

I had already check

" Tony,

I had already checked the mercury switch and both the ignition & throttle kill switch, There did not seem to be any problem. I will try to crank the engine with the black/yellow wire disconnected as you stated. Do you know what voltage the stator should give and on what leads? Are they all the same? Your advice is invaluable. Thanks for the help.

Regards,

Phil "
 
"Phil,

I think you would pr

"Phil,

I think you would probably be better off using a resistance check for the stator, since you say that there is no spark at all.

Disconnect the wires from the stator to the switchboxes, including the stator ground wire.

Using an ohmmeter, connect the red lead to the blue wire and the black lead to the red wire. You should read 5500-6200 ohms.

Next, connect the red lead to the red wire and the black lead to the black wire. You should read 90-140 ohms.

Repeat this test for the red/white stripe and the blue/white stripe stator wires.

"
 
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