Mercury XR2 150bhp - no spark

[adamnorgan]

Hi,

I have an xr2 150bhp, cant remember the year exactly but i think it's 87. The Stator went 2 years ago. At the end of last year I had saved enough to buy a new trigger and stator, which I did, I have also replaced the oil in the gear box, the water pump, the fuel pump, new 80 amphr battery and spark plugs.
It worked for a about 5 mins (I stoped and started about 3 times just to check everything was working) great! I thought.
Then it just cut out (at medium - high revs) like someone had switched it off, there is no spark on any plugs, I checked the kill switch and that doesn't seem corroded.

Does anyone know what it could be? I love the engine but might have to get rid if I don't have some luck soon.

Cheers

A

 

[j_martin]

Re: Mercury XR2 150bhp - no spark

There's a kill switch circuit that goes right to the switchboxes. I believe it's the black with yellow tracer wire. They're connected together and are grounded by the kill circuit to kill the engine.

Try disconnecting both of them, and jumper the terminals together and have a test lead dangling from them so you can ground it to kill the engine. Then check for spark, or try to start it.

Other than that, best bet is to get or borrow a DVA and do the formal ignition circuit analysis.

What happened to the original stator? Was it obviously burned?

hope it helps
John.

 

[adamnorgan]

Re: Mercury XR2 150bhp - no spark

Thanks John, I will give it a go. I had to replace the stator because the fly wheel had worn it down on top and expesosed some wires.

Cheers

Adam

 

[j_martin]

Re: Mercury XR2 150bhp - no spark

Thanks John, I will give it a go. I had to replace the stator because the fly wheel had worn it down on top and expesosed some wires.

Cheers

Adam

Flywheel shouldn't get very close to touching it. Something mechanical is wrong, (cracked flexplate, top main bearing ...) or mismatched parts.

hope it helps
John

 

[adamnorgan]

Re: Mercury XR2 150bhp - no spark

John

what is a formal circuit analysis. Think I have a DVA but my electrical knowledge is not great. Would need a list of methods. I have located the kill wires and you are right they are black and yellow.

Am concerned that I might have blown the black boxes and will read an earlier post of yours about checking the box to coil outputs. Had previously checked all coils and they were good.. Forgot to mention also the original reason for failure was trigger broke. Thanks Adam

 

[boatmonkey82]

Re: Mercury XR2 150bhp - no spark

i have replace tons of those packs and i have never seen both fail at the same time . pull that flywheel again and use a merc puller . see if the wheel has ate up the new stator . i think the two blue wires one with a white tracer should have 150v or more while cranking and the reds one with a white tracer should have 50v or more while cranking . there is also a mercury tilt switch by the packs with a short black wire and a short black w yellow tracer . take that thing off and throw as far as you can . it has one screw holding it on and be sure to tape up and black / yellow wires you unhook or cut , oh dont touch them while running they bite good

 

[j_martin]

Re: Mercury XR2 150bhp - no spark

John

what is a formal circuit analysis. Think I have a DVA but my electrical knowledge is not great. Would need a list of methods. I have located the kill wires and you are right they are black and yellow.

Am concerned that I might have blown the black boxes and will read an earlier post of yours about checking the box to coil outputs. Had previously checked all coils and they were good.. Forgot to mention also the original reason for failure was trigger broke. Thanks Adam

There is a list of voltages to be expected at the stator (charge coil) outputs to the switchboxes, as well as bias and coil output voltages in the maintenance manual. It can be found on the web also.

If you don't have spark. First thing is to disconnect the kill wires from the switchboxes. Check them to ground with an ohmmeter. It should be open when the ig switch is on, shorted to ground when it is off.

Next check the stator output with a DVA. If it's good, go on to the rest of the tests.

Back to the flywheel. If it hit the original stator, something is wrong. If that wrong wasn't righted, it may have done it again.

hope it helps
John

 

[adamnorgan]

Re: Mercury XR2 150bhp - no spark

good progress, thanks for the advice, disconnected both kill-wires. Engine now runs. Is the likely kill wire fault at the ingnition switch or at the block. Ignition switch looks in good condition from the back.

There is no mercury switch just the terminal for it,sealed off on a red/yellow wire.

 

[j_martin]

Re: Mercury XR2 150bhp - no spark

Unplug the cannon plug and see if the short goes away. If it does, it's in the cable or harness. If it doesn't it's in the engine.

I don't think you found the mercury switch circuit. The wire to it is black/yellow. Red/yellow is the starter switch to solenoid wire.

hope it helps
John

 

[adamnorgan]

Re: Mercury XR2 150bhp - no spark

By richardnorgan, shot with C750UZ at 2008-08-04

By richardnorgan, shot with C750UZ at 2008-08-04

By richardnorgan, shot with C750UZ at 2008-08-04


Thank you John Have attached some images. Kill wires disconnected and engine starts and runs. whooppeee. Don't know whether the fault is at the gear throttle lever end with the ignition key switch or whether its at the engine solid blocks. Could the actual kill switch be corroded cant seem to get into that to clean it. Any suggestions.

Thanks again Adam

 

[j_martin]

Re: Mercury XR2 150bhp - no spark

The kill circuit has pretty lively spikes from ignition on it. (it bites ya pretty good). The kill circuits, the tilt (mercury) switch, the kill (lanyard) switch, and the ignition switch in the off position are akk parallel paths to ground to stop the engine.

You have to use an ohmmeter to find the path to ground that isn't supposed to be and replace the bad component.

hope it helps
John