backfiring & stalling

[Tim]

Hi guys

This happened to me twice yesterday when the motor was idling and out of gear. I'm wondering what it could be. I checked the spark plugs a couple of weeks ago, they seemed pretty good, but I cleaned them anyway. They're different to car spark plugs though, and I don't know how to measure the gap for the spark. I probably increased the gap when I filed the end them to clean them up, so maybe that's the problem? It still seems to run fine and doesn't have much trouble starting.

I put a new fuel filter in a couple of months ago, so that can't be the problem.

Anyway, I've booked it in for a service because I don't know the history of the motor, and for all i know it has never been serviced.

By the way, it's a 75hp Mariner 2 stroke. It's a 2000 model.

Cheers
Tim

[djmac]

did you do alot of on and near idle speed running?
was it smokey when you started it or running a bit smell and rich?
could be that one of your plugs are fouled now..
some 2 strokes dont really like idle speeds much.
specially merc/mariners
i had a new merc 90 on the back of my last boat and trolling slimeys around bait schools it would stutter a bit.
the best thing was to give it a good run and it seemed to fix itself up a bit.

when was the last service?

[Grantm]

Chugging, backifiring stalling only at idle sounds like idle mixture to me. If you can, slowly turn the idle mixture screw(s) ( try both directions which will either richen or lean the idle mix ) and see if that helps. It may be a very minor thing and this is quite common and easily fixed by adjustment

The idle mixture screws are usually located on the front of each carb and are quite noticeable.

It wont be the plugs i dont think.

Cheers ! :)

[Boppa]

Hi guys

This happened to me twice yesterday when the motor was idling and out of gear. I'm wondering what it could be. I checked the spark plugs a couple of weeks ago, they seemed pretty good, but I cleaned them anyway. They're different to car spark plugs though, and I don't know how to measure the gap for the spark. I probably increased the gap when I filed the end them to clean them up, so maybe that's the problem? It still seems to run fine and doesn't have much trouble starting.

I put a new fuel filter in a couple of months ago, so that can't be the problem.

Anyway, I've booked it in for a service because I don't know the history of the motor, and for all i know it has never been serviced.

By the way, it's a 75hp Mariner 2 stroke. It's a 2000 model.

Cheers
Tim

I just had to replace the Power Pack on my Evinrude 35 cause it was doing the same thing

Boppa

[Tim]

Thanks for the replies guys.
DJ, I don't know if it's had a service before. I've booked it in with a mechanic in woy woy on Wednesday. They're going to give it a service.

I had been running at pretty slow speeds a bit yesterday, so that could be a contributing factor. Anyway, I'll get it serviced by a professional, and also get a service manual for myself to use later on.

Cheers
Tim

[bluecod]

Tim,

Ask the mechanic to check that the ignition advance mechanism is operating freely and is not sticking anywhere on its travel.