Mariner 90 HP 2001 model.

[abc]

Mariner main agent has just fitted a new CDI unit to solve a major misfiring problem.
Result, no change at all. Spark appears to wander from cylinder to cyinder. I am now at a complete loss as to how to proceed and so it would appear is the local dealer. Any suggestions gratefully received (and I do mean any!).
Alternatively anyone wanting a showroom condition, non running, ( 25 hours) engine for scrap price please get in touch as the engine is cluttering up the transom, preventing me from fitting a new one.

[Nos4r2]

How much do you call scrap price?

[9D280]

2 or 4 stroke?
Carb or injected?
low or high (or all) RPM?
Assume ignition circuits are coil per cyl?
if it's got a CDI, what error messages was it churning out?

I assume if a dealer has looked at it they'll have covered all the stuff like are the HT leads / coils operative, trigger plate / spark advance or TPS all working OK etc etc?

Some 4- strokes "fire blanks" on the exhaust stroke to double up on use of the spark circuitry and sabve a bit of wiring inside the CDI. That may explain "random" sparks?

More info Required!

[wavelength]

I take it its a four stroke 1600cc jobbie?
We had a problem with a mysterious intermittent but serious misfire that was taking two cylinders out.
Luckily we have Jim, a brilliant independent mechanic around here(-plus some cowboys eh!) who thought it must be the cdi unit but then scratched his head, talked to another friend in the trade and came up with the fault being the interupter switch. A considerably cheaper fix.
Located on the port side of the motor under the cowling and hidden by the bottom tray the switch is activated when changing into and out of neutral and drops the motor down to 2 cylinders to relieve pressure on the gears during shifts. Ours was interupting but often forgot to stop interupting when its job was done (sounds familiar eh ! )
The switch is now disconnected & engine is fine
Our mechanic says these are a familiar bit of kit on big inboards but had never noticed one/had a problem with one on an outboard before
you may just need to disconnect a wire
If not we will give you scrap money for it and I'll leave it with Jim for a coupla days to sort out!

[abc]

Originally Posted by wavelength

I take it its a four stroke 1600cc jobbie?
We had a problem with a mysterious intermittent but serious misfire that was taking two cylinders out.
Luckily we have Jim, a brilliant independent mechanic around here(-plus some cowboys eh!) who thought it must be the cdi unit but then scratched his head, talked to another friend in the trade and came up with the fault being the interupter switch. A considerably cheaper fix.
Located on the port side of the motor under the cowling and hidden by the bottom tray the switch is activated when changing into and out of neutral and drops the motor down to 2 cylinders to relieve pressure on the gears during shifts. Ours was interupting but often forgot to stop interupting when its job was done (sounds familiar eh ! )
The switch is now disconnected & engine is fine
Our mechanic says these are a familiar bit of kit on big inboards but had never noticed one/had a problem with one on an outboard before
you may just need to disconnect a wire
If not we will give you scrap money for it and I'll leave it with Jim for a coupla days to sort out!

I am in Norfolk so you are too far away to help really. The engine is still with the dealer who is still trying to fix it but I do not hold out a lot of hope, although the problem does indeed sound like the one you had.
Sad thing is the motor looks like it was just fitted yesterday. I suppose i might get a few bob for the prop though. !

[Nos4r2]

Originally Posted by wavelength

If not we will give you scrap money for it and I'll leave it with Jim for a coupla days to sort out!

Oi! I was there first!

[wavelength]

I am in Norfolk so you are too far away to help really

I was hoping I had done! Point the mechanic in the direction of the switch or do it yourself-matter of minutes to disconnect. It may not be the culprit but there's no harm in trying.

Oi! I was there first!

I'll race ya - well no I wont cos we have one (with a mercury badge) that we really dont use enough. It has a test run, gets serviced, sits about for months, has another test run and a service etc etc . Must get round to selling it and the ocean pro its attached to! Just never enough hours in the day-must get up earlier!

[outboardtech]

ABC you have TIMING PROBLEM HERE if that outboards spark is jumping all ove rthe place . Surely the dealer can FIX that . Get them too pull the flywheel off and check the woodruff KEY on the crankshaft ?? If that KEY is brocken that flywheel will be turning and obviously trying to turn the crank and the timing and spark will be all over the place . I have had a few of these in the field . just another check really . baz

[willk]

Reading this one with interest. Can't help you with technical advice (that given sounds good)

Reading between the lines though, I'm seeing a Faulty Dealer warning light and I think you should replace him immediately. Once a Dealer fails in this way, it's only a matter of time......

[JSP]

Originally Posted by wavelength

I was hoping I had done! Point the mechanic in the direction of the switch or do it yourself-matter of minutes to disconnect. It may not be the culprit but there's no harm in trying.

I'll race ya - well no I wont cos we have one (with a mercury badge) that we really dont use enough. It has a test run, gets serviced, sits about for months, has another test run and a service etc etc . Must get round to selling it and the ocean pro its attached to! Just never enough hours in the day-must get up earlier!

I'm not far from you dave, leave it with me and I'll make sure it gets used