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1998 Mariner 40HP 2Cyl - Changed Stator,but got a explosion when cranking.

iagv

New member
I got a Mariner Marathon 40 HP, 2 Cyl, 2 Stroke, year:1998, S/N 0G600358.

The motor died and had no spark. After all testing, the stator was bad, so I changed it today. I install it in the very same position as the original, and the flywheel position is the same as the guide pin in the axle does not allow to install different.

After installing all, I did test voltage from stator and spark while cranking and all was ok. However when I did try to start it I got what I consider a explosion after a few pulls (3-4). :confused:

I rechecked all and tried again and the same, I got another explosion.

I checked the trigger position and I think it's the normal, though no sure if my kid screw in or out the pin connector to throttle and caused a mis-position of the trigger.


Could this be the reason? or it could be due too much gas going into the cylinder due the too many pull during the diagnostic and test.

Any advice is highly appreciated.

Gerry
 
Re: 1998-Mariner 40HP 2Cyl - Changed Stator,but got a explosion when cranking.

was it an " explosion when cranking." or was it a backfire? make sure the sparkplug wires are on right. make sure the flywheel key is not broken and letting the timing slip. let us know.
 
Thanks for reply coueytwo.

Here is an update of some testing done over the weekend:

- to answer your question: Really not sure, I assume a backfire is done at exhaust due to heat, but in this case it was cold as I just tried to start motor. It was more like a normal fire alone in one piston, perhaps with too much gas, but was not able to start and continue running. :confused:

Since it was sitting there for a few weeks I assumed it needed a carb cleaning. I did so,but really found the carb really clean.

I reassemble, adjust all screws (idle mix, idle speed, throttle cables) as indicated in Mercury/Mariner service manual and in Seloc manual.

I tried to start it again and after a several pulls and different throttle positions, it started, though in a kind of rough idle speed despite the fact it was at full throttle.

I was able to throttle down to minimum and it run for a minute and then I shut it off. I did try again and it took me several tries until it was on again.

there are 2 things I noticed:

- it was not being able to pull water out of tank or with the flushing ears connected, so I assume it low in rpm and impeller not being able to raise water all the way in. Note: I did a check on impeller and it's new. changed a few weeks ago. I was able to blow air all the way thru piping, though it was ok before to make sure there is no obstruction.

- During the short period on, I was able to move trigger (advance/retard spark - see picture) and I notice I could get it run at better RPM with half throttle. this indicates that I have an issue with the trigger position and spark advance/retard. I guess it was due my kid messing around with link rod extension.

So, after being testing all afternoon and above results, I was not able to adjust idle and spark due the lack of water flow - not really wanting it to overheat.

My best guess now is try to start it, but making sure there is water flow to work on idle and spark. I was considering if I can take lower unit and connect a hose to the waster piping to make a water flow thru it even if its rpm's are not enough. (Also I think I need fresh gas mixture, as this one has been sitting around for more than 2 months).

if someone can confirm I can do the cooling using the hose as I'm proposing or the lower unit is require to start an outboard. Also, I did not find anything related with the length of the link rod as initial adjustment (unless you´re no supposed to touch it ever :( )

I will appreciate all your advice on this case. I'm attaching a few pics of motor, CDM's (which I'm sure they are in correct position) and carb/idle/spark adjustments.

Thanks in advance to all, Gerry

mariner1.jpgmariner5.jpgmariner4.jpg
 
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I really can't tall at this time. I did not consider that yet. I'm assuming compression is ok as it was before.

Spark jumping, I would need to test. any recommendation how to do it w/o a gap tester? What I can tell is that spark looks ok (white & able to jump on spark plug) on both cylinders
 
You are assuming , which is not good trouble shooting.-------------Once more,and only once, what is the compression and will the spark jump a gap of 7/16" or better ??????
 
racerone:

I got a time and I did the testing to measure spark gap and compression. Spark is able to jump at least 7/16" on both cylinders.

Also I did a set of compression tests and they were at 100 PSI each on both testing rounds. I also did another check on the impeller and it´s ok (it´s new, installed before trying to start it with stator changed).

Any advice is welcome.
 
The " explosion " or backfiring seems like it is timing related.-------------------Put timing ( TDC ) marks on the flywheel ( use tape if you like ) and see where the engine fires while cranking.
 
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