1991 Mercury 175XRi - nothing happens when you turn the key to start.

[JMO1]

I recently had another thread here, and thought my problems were behind me. The original issue seemed to be fixed by replacing the Trim Down solenoid. What I didn't know at the time of that repair was that the power wire at the remote throttle was worn to the point of the copper wires being exposed. The trim down was working find for the few few short trips on the water, and then a few days later while heading out of our bay at a slow speed, the motor quit and wouldn't start, as in nothing happened when I turn the key - no click, no engine turning over, nothing. At this point, the trim down or up didn't work either.

I suspected some type of electrical issue, and then found the pinch-damaged power wire at the remote throttle at the console. I also pulled the cowling off and found 2 glass cylinder type inline fuses, 20 amps each. I replaced both of those fuses, and now the trim up works again, but attempting to start the motor still has nothing happen.

It seems like this damaged wire may have blown out my Trim Down solenoid again, and also blown a fuse other than the 2 I replaced, that may explain why the motor does nothing when I attempt to start it.

After replacing these 2 fuses, my bilge pumps and trim down now work again, so I don't think it's battery related for the not starting issue.

I will attach pics of the 2 fuses I replaced under the cowling, and hope someone can point me to other fuses that may be an issue. I looked under the console where the ignition wires are and I don't see any bad or disconnected wires, and I don't see any fuses there either.

 

[jimmbo]

Start with the Battery, fully charged? Are the connections clean and tight, Is power getting to the solenoid? Cables can fail internally.
Can you bypass the Solenoid, and the engine ground, with Booster Cables directly to the Battery, to see if it will crank?

 

[JMO1]

Thanks jimmbo,

I haven't tested like you mentioned yet.

I'm planning to test the Solenoid by connecting a pair of jumper cables to my starting battery by connecting the + battery cable to the incoming + connection on the Solenoid (top red circle in my diagram), and then connect the - battery cable to a bolt on the engine block, and then finally disconnect the start wire (Yellow with Red Stripe) from the Solenoid and touch it to the + battery cable connection on the Solenoid. I think this will tell me if the Solenoid is the issue or not, correct?

I was also planning on doing another test where the + battery cable connects directly to the Starter's + connections, and then ground the - battery cable to a bolt on the engine block to see if that has the motor attempt to start.

Is my plan good?

 

[dsiekman]

Sounds like you may have a short somewhere. Another thing to check would be your neutral safety switch. If you have bare wires at the throttle/shift it may have worn through as well.

 

[Faztbullet]

Do you hear the fuel pump run when you turn key to on???

 

[JMO1]

I don't hear the fuel pump or anything.

I did use a 12v tester tool, the kind with a little light bulb, prong, and ground clip.

I tested all 4 red wires coming into the Starter Solenoid, and all 4 lit the lamp.

I then tested the Yellow\Red wire connection to the Starter Solenoid, I believe this is the key switch wire. I had my wife turn the key to start 2 or 3 times and hold it there while I had the test probe on this connection and we couldn't get the lamp to light.

Does this prove it's an issue for the Key Switch wire, between the console and the Starter Solenoid?


Thanks

 

[Faztbullet]

Sound like your not getting 12v to switch. Check for 12v in front and behind fuse holder next to solenoid.

 

[JMO1]

I used a 12ga jumper wire from the Yellow\Red Wire connection to the main positive cable in on the Starter Solenoid and the Starter shaft did start to turn.

All the other red wires connected to the main incoming positive terminal on the Starter Solenoid were hot when I tested those.

Should I know focus on the key switch connections at the console?


Thanks

 

[JMO1]

I used a 12ga jumper wire from the Yellow\Red wire connection on the Starter Solenoid to the main incoming positive positive post on the Start Solenoid, and the when I did so the Starter shaft up to the flywheel began to rotate.

With this being the case, should I focus on the console and the Yellow\Red wires and connections, and the power wire you mentioned?


Thanks again.

 

[Faztbullet]

If you do not hear the fuel pump come on when you turn key to start you are not getting 12v from fused side to ignition switch. If no voltage at switch fuel pump and starter will not operate