1988 mariner 135 marathon idle/ starting issues

[qwest]

I recently purchased an 18ft angler 180 with a 1988 mariner 135 marathon off craigslist, I've had problems since day 1 but mainly just starting the motor and getting into gear. it seems that once it warms up it will cruise all day with no issue. I have to start it out of gear with throttle for it to fire and then shift quickly in order to get it in gear without cutting out. also when I come back from the water, docking is an issue because it always cuts out when shifting from a lower idle.

This week I found that the starboard side cylinders had no spark, so I ordered and installed a new power pack This seemed to temporarily fix the firing issue but not the idle issue, and a few days later it was back to where it was before the power pack.
It has brand new spark plugs and the carburetors are spotless
Any ideas?
thanks

 

[SteveVT]

Got good grounds?

 

[qwest]

I would think so, had to switxh coils around to make sure they werent the problem before the powerpack fix. I feel like that wouldve presented itself in that case

 

[Faztbullet]

Sounds like a stator has dropped a bank....

 

[Chris1956]

Is the choke working? Some motors have choke plates, some have various kinds of enricheners. It appears that you have a solenoid-type enrichener. Does it drain fuel from the top carb to the lower carbs to help cold start?

Of course that issue would be in addition to your lack of spark.

 

[qwest]

I don't believe it is a stator issue solely because it will run great from mid-high throttle, I think when stators go it results in loss of power at WOT, I could be wrong.
As for the choke, it has an electronic enrichener but I know that it works because I hear the click when it engages as well as see fuel dribble down the carbs.
could it be a matter of adjusting idle stop screw?

 

[qwest]

I also wanted to note that compression is 108-112 in all 6 cylinders

appreciate the feedback

 

[Sniderah]

I am having a similar problem with my 1988 Mercury 135hp outboard, so if there are suggestions it may help both of us. My idling problem started after participating in a slow parade around the lake on Canada Day. It will not idle without using throttle, and will stall when slowing down to dock. To get going I have to rev up and slam it into gear. Acceleration is a bit rough, but then it will cruise nicely for water skiers and will reach normal top speed over 40 mph in my 18' Searay Seville.

i took it in for service and was told that cylunders 2,4 and 6 failed a leak down test (40%,40%,30%) and that my main seal under the flywheel is leaking badly, so motor is done...today I did a compression test and got the following approximate readings 112, 112, 118, 121, 114, 120. Also I could not find any sign of oil from the main seal under the flywheel. It does smoke like heck though. Suggestions that would help both qwest and I would be most welcome! Thanks.

 

[Faztbullet]

I don't believe it is a stator issue solely because it will run great from mid-high throttle, I think when stators go it results in loss of power at WOT, I could be wrong.

A stator has a low speed and high speed side...low side fails no spark below 2200RPMs. High speed side fail no spark after 2200RPMs(WOT)

 

[qwest]

thank you faztbullet, that does make a lot of sense. I am meeting with my mechanic this week. I will run it by him and hopefully we can test it

 

[qwest]

do you think a new stator would help the firing issue? a lot of times it will just crank when starting and then fire after a couple of tries

 

[qwest]

I just replaced the stator. I have spark on all 6 cylinders but the motor is still not firing.plugs are fine, battery is charged, I have no idea where to go from here. Any ideas?

 

[Faztbullet]

Need three things to run compression, fuel and spark. When you say motor still not firing what do you mean??? wont start? hts and wont start? just cranks?

 

[racerone]

With 112 PSI compression I would remove that cylinder head.----In the big picture a head gasket is cheap.-----You will learn a lot by looking at the cylinder walls.---Spark but " not running " then I would check the flywheel key.

 

[qwest]

Faztbullet- Yes the motor just cranks and cranks. The spark tester I was using was from harbor freight though, and my buddy who was checking it said it was more of a flashing spark than continuous.
recerone- Do you know what the compression should be on it?

Thanks for the help

 

[Faztbullet]

Should be a rapid spark that should jump a min 3/8 gap...

 

[Dukedog]

flywheel/crank doesn't use "key".. will only go on one way... have you "turned" any screws that would change any thing related to idle speed, idle timing, and or wot timing?.. do you have a oem manual?.. get a spray bottle with a "pre mix" (50 ta 1) fuel in it.. squirt it in tha carb throats when ya turn it over.. if tha motor spits, farts or does anything different than what ya describin', like its trying ta start ya gotta fuel problem.. if it doesn't do anything ya got a fire and/or timin' problem.. its also possible that you have both fuel and fire/timin' problem.....

compression can be a very wide scale depending on who ya ask.. merc will not state a given good/bad compression number.. they use a very "wide" scale recommendation.. tha 2.0 could vary from 110 ta 130 for a good reading.. tha gauge used, tha procedure used has a big influence on numbers also... reasons merc won't commit ona given number.............