Mercury Blueband 700

[Lasermatrix]

Hi All,

First post, new member, go gentle

I have just bought a boat, it's not a rib (that's coming later!) which has the above engine. We believe it to be a 1989 model.

Having a slight problem with it, sometimes when the key is turned, the engine will not even attempt to start, no click from the solenoid, starter does not engage.

The Battery has been charged and is in good condition, I'm fairly good with electrical systems, so have performed a few tests..

Have tried the usual test of jumping the solenoid to crank over the engine, this works.

Measured the input terminals on the solenoid when the key is turned, I read no voltage.

measure from the positive terminal on the solenoid to one of the earth braids, I read 12v

It's almost like the negative side has no earth, but I can do a continuity test between parts of the engine and the negative terminal and others I can't (If that makes sense)

It's almost like there might be some sort of safety interlock somewhere that prevents you from starting the engine with the cover off??

After much faffing about like this, I looked at the front plate that covers the catches of the engine cowling, noticed the two metal prongs at the bottom that lock into the engine, I wondered to myself if the interlock (if there is one) is made only when this cover is put on, so I snapped the cover on (without the cowling) and tried again, still nothing, I then put the cowling back on and tried again, this time it worked!

I can't explain this, unless there is some kind of interlock. Does anyone have any experience of this? It seems unusual to me.

Best Regards,
Chris

[dctucker]

Personally I have no idea, however, the best online resource I have found for Merc is the iboats.com Mercury forum . Be prepared with the serial # of your motor. There are some guys there that REALLY know their stuff.

I have an older (1980) Mercury 80 hp 4 cylinder on my Searider, and the iboats guy have really helped me out with some troubleshooting. Now it starts right up and purrs like a kitten, thanks to their help.

Dan

[jwalker]

Originally Posted by Lasermatrix

.....Measured the input terminals on the solenoid when the key is turned, I read no voltage.

Does that not indicate a break in the solenoid circuit? Does the cover lean onto the harness when it is fitted?

I wouldn't have expected and interlock. If there is one, there has to be a microswitch or magnetic switch somewhere.

[Paul F]

There is no interlock on the cowl, the only interlock is the "in gear"one in the control box. Are you getting volts on the red and yellow wire which energises the solenoid when keyed to start??
Paul

[Lasermatrix]

Thanks for the replies

Yes, I have measured across the yellow and red wires during starting, I read no volts. However, as I say, sometimes the engine does start, or I can bridge a wire from the yellow(neg) terminal to another earth on the engine and I can start it via the key.

It suggests a bad earth to me, I was just hoping someone else had experienced this and could tell me for sure

Or could it be that the throttle control is not registering in neutral and the controlbox interlock is engaging??

[dctucker]

Originally Posted by Lasermatrix

Or could it be that the throttle control is not registering in neutral and the controlbox interlock is engaging??

This is the most likely possible problem, I would guess. I've never heard of a cowling interlock on any outboard.

[Mr-d]

Hi Matrix,

If you have a "Quicksilver" control box, and i believe the other mercontrol boxes have the same, there is a sensor/breaker that makes sure that you are in neutral when you attempt to start it. make sure that this thing is not stuck and refusing you to let you start your engine, I dont know what exactly it does, i believe it just interupts the second stage of turning the key not sure if it bridges something, or disconnects something... you'd have to see if it still works by checking the circuit of it with your multimeter. Its a yellow-red coloured cable going in and out the box, the bit is called a "Neutral start interlock" If you want some pictures of the diagrams, let me know and i'll scan them in for you.

Cheers,
Daniel.