200 Merc bogging when throttle is reduced

[captaing]

from high RPM. This is a 2001 model year 200 XL saltwater V-6. It tends to bog down and die when I go under a ~3000 RPM after running flawlessly at high RPM. This happened some last year where I would be going offshore at high RPM but when I would reduce throttle it would bog and die. It also likes to increase and decrease about 500 RPM as I am cruising without touching the throttle. I decarbed the motor (did not change plugs since the decarb was supposed to clean them as well), replaced the water separating fuel filter as well as the in-line screen filter and it ran very well the first trip out. The second trip it bogged again at low RPM (~ 2500) and had to juice it to keep it running. I also have a rough idle (shakes like it has Parkinson's but that, I assume, is attributable to the mechanic (when I bought new) "richening the carbs". He said that was a better setting. Any ideas as to what the issue is? Any help would be appreciated.

 

[captaing]

Re: 200 Merc bogging when throttle is reduced

Has anyone seen this before?

 

[captaing]

Re: 200 Merc bogging when throttle is reduced

Moderators, please tell me if I asked something in an incorrect manner. I am new to the board and may have done something that prevents me from receiving a response from those that are knowledgeable. Thank you.

 

[michaelbr1]

Re: 200 Merc bogging when throttle is reduced

People on this board (many of them very knowledgable) tend to take a bit longer to answer posts. They're probably not looking just now, but someone will come along soon. <br /><br />What brand is your motor?<br /><br />I have a friend you just last year was experiencing what sounds like the same problem, and he ultimately ended up spending $3500 on an overhaul. I feel like he was kind of quick on the jump to agree to do it because he didn't look at too many other things that could have been causing the problem. But for whatever that's worth.

 

[captaing]

Re: 200 Merc bogging when throttle is reduced

It is a Mercury. It seems to run like a top at high RPM but it is a ****ens to start the first time and has the other symptoms I spoke of. Thank you for repsonding but I hope I am staring an overhaul in the face. This motor has only 100 hours on it.

 

[gss036]

Re: 200 Merc bogging when throttle is reduced

I run a 1989 200 Merc and anytime I start getting a surge, it is because of water in the seperator. You mentioned that you had changed the filter, was there water in it then?<br />My 200 also idles rough, just the nature of the carbed 200's I think.<br />Hopefully some with experience will help out. You might check the FAQ forum or repair suggetsions, lot of info there.<br />Maybe change your header title to need help w/200 Merc surging problem???

 

[JB]

Re: 200 Merc bogging when throttle is reduced

There is no problem with your post, CaptainG, but your title gives no information about your engine or your problem. That wont attract the helpers who are experts on your engine and problem.<br /><br />The "edit post" icon will allow you to edit the title as well as content.<br /><br />Good luck.

 

[KCLOST]

Re: 200 Merc bogging when throttle is reduced

Check the spark from each spark plug lead, at idle...<br /><br />Check one at a time, using a spark gap tester you can buy at any auto parts dealer... Make sure each lead is grounded when testing... Start your testing with a 1/4" gap...<br /><br />If you have a spark on all cylinders at 1/4" increase the gap to 3/8" and retest. Let us know the characteristics of each lead test... This will determine if it's electrical or not...

 

[jim dozier]

Re: 200 Merc bogging when throttle is reduced

Is this an EFI or carbed engine? 4-stroke or 2-stroke?

 

[captaing]

Re: 200 Merc bogging when throttle is reduced

gss036....thank you for the info on the filter. I know a good bit about boats and some about motors but I have no idea how to determine if water was in my fuel/water separating filter. Every time I change it out it always appears full of gas and I end up spilling some. If water were there, where would it be? Also, is there any harm in adding Starbrite water remover to my tank in an effort to burn off any water that may be present? Thank you. I will also look into buying a spark tester for the plugs as suggested by KCLOST.

 

[KCLOST]

Re: 200 Merc bogging when throttle is reduced

I'm not sure about the water because I've never had that problem... But you should see it as water a gas don't mix...<br /><br />You can also try one thing that is very simple...If you have a remote tank, let's say 6 gallons in size, fill it up and try running it with truely fresh fuel out of that tank, after you have cleaned the seperator... You may have to buy a new fuel line from walmart that will work with that set-up, requiring the correct fittings and a fuel bulb (around $10). See if that makes a difference....