3000-3500 engine stumbling

[sgcheek]

94 Evinrude 200 OceanPro acts like the low speed jets in one or more carbs have trash in them.--Pulled carbs for a quick look tonight. Nothing obvious stood out, other than the floats looked high on a couple of carbs.The engine seems rich at lower RPMs, but seems lean around 3 to 3500<br /> It seems like it does not want to carburet very<br /> well at those engine speeds. Compression all 95-105 (cold engine, outside airtemp 35F) It's too cold to work outside, but it has to be done--the Stripers are biting!! Could I have a weak coil, and how can I be sure. Anything else to look for?

 

[OBJ]

Re: 3000-3500 engine stumbling

sgcheek....a quick look really dosen't get it. You need to pull the carbs apart, hose them out with carb cleaner and follow up with compressed air. It don't take much to throw a jet outta wack.<br /><br />How do the plugs look? Spark on each cylinder jumps a 1/2" gap with a hot white spark? Hose and fuel line connections all tight?<br /><br />Just some things to look at. Keep us posted.

 

[sgcheek]

Re: 3000-3500 engine stumbling

Done lots of carbs--motorcycles, chain saws, Honda cars when they had carbs,etc,etc. I had already pulled the bowls, blew through all low speed pickup tubes by mouth. All seemed about the same. Air bleeds 35 and 42. Also pulled the side plates off.I plan on going through the carbs completely tomorrow. Is an OEM manual available?<br />I've not had much confidence in Haynes or others.<br />Sometimes just too general. One other thing--I found a short--3/4 inch long piece of orange o-ring material lying under the carbs in the cowling, but I don't see anything with this type/color at the carbs. Any ideas where this is used in the engine? Any help is greatly appreciated!!

 

[sgcheek]

Re: 3000-3500 engine stumbling

Forgot to say about plugs. Nice color, but very oily looking. Have about a one mile idle in no wake zone from yesterday. Engine seems pretty oily looking on port side all around primer and oil pump area.

 

[Dhadley]

Re: 3000-3500 engine stumbling

What type/brand of spark plugs?

 

[sgcheek]

Re: 3000-3500 engine stumbling

Don't recall the number, but using the recommended Champion plug.

 

[OBJ]

Re: 3000-3500 engine stumbling

The OEM service manuals are still available through Johnson/Evinrude dealers along with parts manual and owners manual. Or check the link below.<br /><br /> http://ww3.kencook.com/evinrudejohnsonmanuals/

 

[seahorse5]

Re: 3000-3500 engine stumbling

Use the Champion QL78YC plug gapped at .030". The orange "spaghetti seal" goes in the groove at the bottom inside of the air silencer. Clean off the oil residue and glue it into place.<br /><br />Drivability problems in the mid-range can also be caused by incorrect propping. What rpm does the motor turn with full fuel at WOT? It should be very close to 6000 rpm for best results.<br /><br />There is also synchonization between the spark advance and throttle opening that is critical for smooth operation in the mid-range. Use the proper service manual to make sure the adjustments are correct.

 

[sgcheek]

Re: 3000-3500 engine stumbling

Thanks for the reply. That plug number is what I use. When it runs right, I can get 6000 at wot. I am going through the carbs, and will check all other specs.

 

[sgcheek]

Re: 3000-3500 engine stumbling

I finally got the time to dial in my engine. I pulled all the carbs, cleaned them, and reset the floats. (one was quite high)Re-synched the carbs, sand blasted all the plugs. Replaced thermostats with only one bolt breaking off. One t-stat was blown and pieces fell out when I pulled the cover. Now it makes sense why the engine always seemed to go on fast idle like a cold start on any restart. She now idles very smoothly without shaking and also accelerates better. It will still take a little air bleed screw fine tuning to get her just right. Also perhaps the best $150.00 I have ever spent on any boat is the Navman fuel flow meter that I just installed prior to my last trip out on the boat. Now I always know EXACTLY how much fuel I am burning and how much is left. Every boat ought to have one. Much, much better than fuel level gauge.<br />SGC

 

[Mirko]

Re: 3000-3500 engine stumbling

So what's a good place to get a navman fuel flow meter?<br /><br />Thanks,<br /><br />Mirko

 

[rickdb1boat]

Re: 3000-3500 engine stumbling

Single Engine Fuel Flow Kit - for NavMan <br /><br />Or:<br /><br /> FUEL 2100