93 johnson 200 venom RPM changed

[lynchburguy2002]

Ok guys,
1993 Johnson 200 venom (VJ200SLETC) Serial # G03203074
Fresh fuel ( premix 50:1)
new plugs Champion QL77JC4 set on .030 good spark on all 6
Compression is around 90-92 on all but one which is 85-87
recent rebuild on all 6 carbs. ( cleaned, flushed ports)
new primer bulb (omc)
new inline filter (omc)
6" jackplate ( will measre this afternoon)
141/2 x22 raker
have taken the boat out twice (93 hydrasport ls200) and she ran good. little sluggish on the take off, but pretty good for a 20' boat loaded with gear and two eager fishermen! Had her running around 5200-5300 rpm, Not sure of speed np GPS yet..... but all seemed fine but then all of a sudden she lost about 600-700 rpm! water was choppy and there was a bit of traffic so i was in and out of it trying to maintain a decent plane and not toss my passenger! I trimmed up a bit more to see if it was just "me" but she wouldnt come above 4600 rpm and was noticible slower. we stoppped and I checked the fuel line, bulb still hard not rock hard but firm.... wasnt smoking excessivle, no rattles, vibration, or anything that seemed unusual. but then tried to get her back on plane and nothing! she wouldnt come over 2800-3000 rpm and was bogging as i advanced the throttle. Fouled plug??? changed them, fixxed it for the first run but as soon as I slowed and tried to plane again...she bogs. decarb?? ran a gallon of fresh premix with a can of seafoam. (havent checked compression improvemnets yet) but she ran better but still not able to get up in the 5300-5400 range. and realy slow on the hole shot. has to slowly build rpm;s and then she gets out of the water as I trim up. what have i done wrong? are there any simple checks i have missed?

[ChampioNman]

I'd check compression first, then I would mark the flywheel at TDC for each cylinder and connect a timing light to the motor and check each plug to verify fire. You may find on isn't firing if so you can try swapping that plug wire and re-testing if that doesn't get it try swapping the coil with another cylinder. If that doesn't get it then more than likely the power pack.

[lynchburguy2002]

Thanks CM! I had a feeling it might be electrical, could I have spark at idle on the hose and then not when putting a load on the engine? Like its breaking down or weak?

[ChampioNman]

Yep back pressure from the H20 will tell you quick but a timing light will tell you quick. Just be careful because flywheels eat flesh!

[lynchburguy2002]

thanks,
Going to look everything over this morning and make sure I didnt overlook something and then pull it to the lake. willl let you know what i find.
How far is Lake Hartwell from Lynchburg Va? I might just have to let you have it for a few days and get it back to the way it should be.

[ChampioNman]

Looks like about 5 hours http://www.mapquest.com/maps?1...2s=SC

[hulapopr]

champman will fix it wish he had shop close to here,,anyway my 96 did that a few years back and the magnets came loose under the flywheel, couldn't find the problem nor the local shop,i run a time or two more and then it was easy to find,after everything under it was junk..and i drove 3 hrs to ky lake and it wouldn't start..

[lynchburguy2002]

well, I can rule out flywheel.... changed that yesterday, had picked up a bunch of parts on ebay as a package and thought i better try each thing until i figure it out. But no luck with the flywheel, same symptoms

CM: I just pulled the carb breather box and noticed it was a bit oily. so figured I would run it on the hose and see what happens. Looks like one carb is blowing back into the breather. seemed odd so i pulled the carb, checked it out all looked fine, for the hell of it I swapped it with the one just above it and it did the same thing on the same cyl. not sure how the cyl order is but it is the lowest carb on the right if facing from inside the boat. this is also the cyl that has the compression a bit lower in the low to mid 80's and the rest are all 90-93 what would cause this?

[ChampioNman]

I'd look at the gaskets.

[lynchburguy2002]

right on again CM! blew a head gasket and was leaking at the intake in the same area! should have her back in thea water this weekend! thanks again