Johnson 200 venom idle&charging

[todd foster]

Hi.I've been reading here for about 2 months now and most of the replies are fantastic.Anyway what I have is a 98 model johnson 200 venom model # j200stlec.The boat sat for 2 years from previous owner and I picked it up for next to nothing.The first thing I had repaired was to have all carbs rebuilt.Then had the link and sync done,then ran johnson engine tuner(the kind you spray into the carbs).Well it runs like a bad outa-hell top end but after the engine gets warm it won't hold a good idle from that point on.The quick start is working and turning off in a timley manner,but right when the quickstart disengages when the motor is just cranked up in the water it idles pretty good.I pulled all plugs one at a time ,grounded them while all of the other coil-packs were disconnected and all plugs had a very good blue spark with audible tick.I also noticed my charge guage shows low charge and my digital voltmeter reading at idle with boat on the hose is around 12.3 volts.I was looking for around 14 volts with no accessories on.I think the guy that rebuilt my carbs didn't do such a good job because I wouldn't think it could run so good at w.o.t but so cruddy at idle.When I let it idle in forward for a while and try to give it gas it will fall flat on it's face then if I mess with the throttle for a sec it will pick up and do just fine.I am lost because I thought this guy was a good omc mechanic but I don't know.Any suggestions on the charging system and idle would be greatly appreciated.Thanks

 

[todd foster]

Re: Johnson 200 venom idle&charging

Anyone,please.I've read several articles on different engines that are having similar problems but I'm not sure if the remidies for other engines would pertain to mine.Thanks

 

[Silvertip]

Re: Johnson 200 venom idle&charging

I'm not familiar with that engine but it appears the idle mixture and idle speed may need to be adjusted. That needs to be done in the water. It may be the rebuild did not get the idle passages clear of varnish and debris. If the carbs have idle mixture screws I'd check adjustment. If that doesn't help more checking is in order.

 

[todd foster]

Re: Johnson 200 venom idle&charging

I am not farmiliar with the idle air bleed adjustment procedure.The idle timing with boat in gear on trailer is about 6 degrees after top dead center as per the manual but the book does not describe how to adjust the idle bleeds on each carb to make sure all of them are set right.

 

[sikpnter]

Re: Johnson 200 venom idle&charging

according to the manual you should turn them in all the way then 5 turns out. Might have to fine tune

 

[ezeke]

Re: Johnson 200 venom idle&charging

I think you may want to re-torque the carburetor to manifold bolts. A little air leak can cause those symptoms. Did you remount them with new gaskets?

 

[todd foster]

Re: Johnson 200 venom idle&charging

The mechanic that rebuilt my carbs also changed the intake gasket.I don't think he adjusted the carbs right.He used all new gaskets as far as i know but i'm not bringing my boat back to him ever again as he is kinda shady.He said that he put the motor in a back down tank put it in gear with a fuel pressure guage and when reading got below 3 psi is when the engine would act up?how can that be when it runs fine at anything but idle?Also the plugs come out wet and black.