Mariner 200hp running rough

[TonyD1976]

Mariner 200 hp 2.5 litre v200 serial# ODO32268
I have been reading up on a few posts here and tried a couple things but think its best to post a new thread and start from scratch. Heres my situation.....

I ran the boat across the lake a couple times durring a morning fishing trip and ran great. I decided when we were done fishing to open it up all the way for the 1st time and see what it would do. It ran great and when I idles down the motor acted like it had a severe missfire going on. It was jumping around and shaking the entire boat and from that point on all it will do is idle and when I give it gas it chokes itself out. It will fire back up but does the same. I idled for about 30 minutes back to the ramp. The entire time I had water pressure and a pee stream, yesterday took it out to test and no water stream. I have a low water pickup installed so it may have just clogged and have nothing to do with the issue but wanted to mention everything.Sorry for the long version but want to be thorough.

Here is what I have checked....
installed new plugs, have great spark at all plugs, removed the white/black jumper between the 2 boxes and no change, removed the 2 yellow wires coming from the stator to a terminal block which then goes to what I think is my rectifier/regulator (4" x 6" silver box with grey tach wire coming out of it) and it seemed like maybe a slight change but not a smooth running motor at that point. Again sorry for the book I just wrote. Any ideas?

 

[j_martin]

Re: Mariner 200hp running rough

What's the fuel system, Carb or EFI?

 

[TonyD1976]

Re: Mariner 200hp running rough

It has the 3 carb set up on it. Is there a way for my motor to jump timing like a car motor? Is the timing controlled by a module?

 

[TonyD1976]

Re: Mariner 200hp running rough

Any suggestions?

 

[j_martin]

Re: Mariner 200hp running rough

It's not likely to jump time. There's no mechanical thing to time like valves in a 2 cycle engine. They're real simple. They go squish-bang. If you have compression, fuel, and spark (timely of courrse) they run.

That said.
Pull the plug wires one at a time at idle, and see if a particular cylinder or 2 is troubled.

Check compression. Without squish, no bang.

From your symptoms, the next check would be a dva voltage check on the stator charge coils, checked at the switchboxes. The yellow 40 amp coil to the charging system (regulator) is a different deal, just happens to also be in the stator. If stator is bad, replace it.

Try temporarily disconnecting any advance or idle stabilizer modules.

Check yer fuel. A gob of snot can find a lot of places to wreck havoc in a 6 carb setup. (2 x 2bbl, essentially 6 separate carburetors.) Should be able to isolate the particular carb with the plug wire routine above.

Check the obvious, blowback through carb while cranking = bad reeds.
Carb and timing linkages all working normally

Once-over check for bad bleed lines. Spray gasket joints with fine mist of water at idle to detect vacuum leaks.

hope it helps
John

 

[mad57]

Re: Mariner 200hp running rough

Any suggestions?

whens the last time you changed your water/fuel filter? there is a new water filter for the new gas as well, mine runs like crap i change it purrs like a kitten. good luck.

 

[j_martin]

Re: Mariner 200hp running rough

That thumb sized murkery filter barely passes enough fuel when it's brand new and clean, and is about a 100 micron screen, so it passes a lot of chit anyway.

I replaced all my fuel lines, and put in a Racor Fuel/water filter. Change the filter about once a year.

 

[TonyD1976]

Re: Mariner 200hp running rough

Thanks for the help....I will try it all tonight and repost the results.

 

[TonyD1976]

Re: Mariner 200hp running rough

Pull the plug wires one at a time at idle, and see if a particular cylinder or 2 is troubled.

What exactly am I looking for when I pull the plug wires? I pulled one off then replaced and moved to the next and noticed a slight change in the way it would idle on 5 of the 6 cylinders. The 3 on the left and middle and lower on right would lower rpm slightly while removed and then raise rpm when reattached. The top right cylinder made little to no difference if any. Please don't tell me this cylinder is shot, I will pick up a compression tester tomorrow and test all cylinders. Where are the sensors you mentioned for idle control and advance? Thanks!

 

[j_martin]

Re: Mariner 200hp running rough

What exactly am I looking for when I pull the plug wires? I pulled one off then replaced and moved to the next and noticed a slight change in the way it would idle on 5 of the 6 cylinders. The 3 on the left and middle and lower on right would lower rpm slightly while removed and then raise rpm when reattached. The top right cylinder made little to no difference if any. Please don't tell me this cylinder is shot, I will pick up a compression tester tomorrow and test all cylinders. Where are the sensors you mentioned for idle control and advance? Thanks!

OK, I won't tell you. You'll have to wait for the compression test.

Could also be carburetion, or, at idle, reeds, along with a plethora of vacuum leaks and bad hoses.

 

[TonyD1976]

Re: Mariner 200hp running rough

OK, I won't tell you. You'll have to wait for the compression test.

Could also be carburetion, or, at idle, reeds, along with a plethora of vacuum leaks and bad hoses.

OK good news...compression check on all 6 are within 3 psi and lowest was 110 which I would think was borderline but is not the problem here. I checked spark again and its a nice blue fire on all 6. It starts up and idles but gets rough as it heats up and then in the water under a load it will not rev it just chokes out and stalls and barely idles under laod as well. I have to switch from neutral to forward every few seconds to keep it running. When I pulled plug wires individually it stumbled a little on all except the top right cylinder looking from the rear. I did notice the middle carb is wet and seems to be coming from the top carb and running down but not sure. Can I put these 2 signs together and assume the issue is within the top carb now? Would my symptoms described above point to a carb issue like you suggested? Also I run pre mix @ 50/1 , sorry I did not mention that prior to now and the motor dies right away if I push the key (choke) which is normal right if this helps any.
Thanks again, Tony

 

[TonyD1976]

Re: Mariner 200hp running rough

I just thought of one other thing that may help diagnose my issue...when loading on the trailer I can not power load at all. I normally run it up slightly and winch the last foot or so but have tried to power it once or twice and it would bog down and die instantly. Of course this was prior to running badly. >>>> carb issue isn't it <<<<

 

[j_martin]

Re: Mariner 200hp running rough

Check the enricher valve. It should not flow any fuel unless the key (choke) is pressed.

If good, yer gonna have to tear the carbs off and find out what's wrong. Odds are there's some debris in the carbs, maybe plugging jets in #1, and holding needle valves open in others.

You need to replace gaskets when you go through them. They are quite simple carbs, though, and not hard to work on. Replace what's bad, and adjust the rest.

As long as yer that far into it, you might as well pull off the reed plate and check them out.

hope it helps
Kohn

 

[TonyD1976]

Re: Mariner 200hp running rough

Found the issue and it now runs better than ever.....here's a recap for anyone trying to troubleshoot a similar issue. I hate that most people do not recap or end the thread with a resolution.

Pulled 1 plug wire at a time while at an idle to see if there was any change in condition. I found #1 and #2 cylinders made little to no change at all when removed. I then sprayed carb cleaner in short bursts into the top carb which feeds the #1 and #2 cylinders to introduce fuel to these cylinders and see if it raised rpm's any. It did so I knew it was a carb issue at this point. After tearing down the carb , I found that the float needle was almost always shut due to the seat backing itself out (think it was the vibration of the motor at full throtle). On my carbs the needle seat is a removable part. It had backed out almost 4 complete turns thus shutting off fuel to this carb due to the fact that the float had to barely rise to contact the needle. 1st I thought this was the way you adjust the float but not the case. There is a felt washer that goes on the threads of the seat so if not completely tight it would allow fuel past the threads constantly. To adjust the float level you slightly bend the tab that contacts the needle. You want the float to sit level or just slightly below level from what I've found. Hope this helps someone else in the future. Thanks for your guidance John , I really appreciate it!