4.3 GM 1988 omc cobra running bad,HELP.

[Donald Terrell]

My boat which usually ran very well has been stored for a couple years.Last month I took it out after changing fluids and installing a new impellar. It ran poorly like it was running on 4 or 5 cylinders but it would occasionally shoot forward and run good only for seconds though. I noticed that the temp guage was not coming up,at first I thought it was broke,however it wasn't. I replaced the thermostat which was broke open. I did inspect the points,cap,button,wires and two plugs which all seemed fine. I thought I had solved my problem with the thermostat and the engine would run fine after reaching operating temp,but I was wrong. Today it ran just as bad.It normally will top at about 44 mph but today never hit 34mph. At full throttle it would surge and slow on its on.On the lake I removed the cannister fuel filter,dumped gas into a clear conatainer(looked clean, no water) and also inspected the small filter at the carb.I removed the gas line from the rear, built in, never seen it before gas tank. No gas flowed out and I couldn't blow air into the tank.I've read about an antisiphon device.All I plan to try next is the flow rate test of the fuel pump. I read on another post that Bombadier discontinued the stern drive division meaning that parts would get harder to obtain.True?? I usually leave longwinded post as this one but I just want to give enough info,apreciate any help!

 

[whickety1]

Re: 4.3 GM 1988 omc cobra running bad,HELP.

Don...I had the same problem with my 89 4.3 last week. I simply changed to good marine grade plugs. #1 plug ceramic was a little loose,<br />and broke in my hands after pulling it out.<br />My engine is brand new, and had this problem, as I installed automotive grade plugs.<br />I,m learning that marine rated parts are the only way to go...if not for safety alone.<br />Good luck.

 

[Donald Terrell]

Re: 4.3 GM 1988 omc cobra running bad,HELP.

Thanks,yes I am sure that I could use a new set of plugs,been awhile since I replaced them.What brand of engine did you install?What drive? Anyone with additional input please advise!! My points,plugs,distributer cap were very clean. Is it true that Bombadier which bought out OMC is discontinuing making stern drives and parts? Please read my original post.Thanks everyone!

 

[Blk-n-Blu]

Re: 4.3 GM 1988 omc cobra running bad,HELP.

Don, You may want to try to run with your gas cap open to be sure the tank is venting properly.

 

[Elk Chaser]

Re: 4.3 GM 1988 omc cobra running bad,HELP.

My first thought is.............<br /><br />If it's been sitting for two years then more than likely the carb (I am assuming it has one) needs to be rebuilt. <br /><br />You can try running injector cleaner through it but in my experience if the boat has been sitting that long you are in need of a rebuild because the fuel in the carb more than likely evaporated in that time and the soft parts (rubber) are now more than likely shot. That in addition to the fact that all the small ports and seats have gummed up as the fuel evaporated.

 

[Donald Terrell]

Re: 4.3 GM 1988 omc cobra running bad,HELP.

Thanks everyone, I'll try running with the gas cap off the next time I take her out. I've never rebuilt a carb before and I have been reluctant to start turning screws. Do I just purchase a kit for my particular carb? I am mechanically able,sure I could follow instructions. Anymore advice? I think when I do get it running good again,I may get out of boating and sell it.Yeh right.Thanks everyone!!

 

[Airpacker]

Re: 4.3 GM 1988 omc cobra running bad,HELP.

unless you drained the carb before you layed it up, the varnish thats left after the volatiles in the fuel evaporated are still inside the carb, kinda like a coat of varnish engine death. By that I mean that forcing the engine to run at WOT without verifying that the fuel is getting through the carb properly is asking to LEAN burn the pistons. Yes you can buy a carb kit and if you are very comfortable with rebuilding it yourself, then go ahead BUT you will need an immersion bath of some very strong chemicals to get the gum and varnish out of the small passage ways inside the carburetor.

 

[Donald Terrell]

Re: 4.3 GM 1988 omc cobra running bad,HELP.

More advice towards my original post would be greatly apreciated before I start pulling my carb off.What would yaw do? Even when my boat was not in use,I want to remember that atleast every summer I would unwinterize and run on muffs a couple of times before layup again. This boat used to run like crazy good,Now will barely plane. Why do I always have water in the bilge when no water comes in over the edge of the boat?I have a Rochester carb,would it have a composite float? I'm not hearing from alot of yaw.Where are you Lou C? Please read my original long winded post.Please and thanks to those who are responding.