'76 85hp, suspect carb issue

[JasonB]

Took the boat out 3 weeks ago and it ran like a top, never better. Took it out yesterday. Hard starting, rough idle, dies trying to get in gear, just like the last time the power pak blew one bank of cylinders. Tested in the driveway by pulling various plugs and found that the top two cylinders are not firing. If I spray seafoam down the top carb while it's idling, those cylinders pick up. My gues sis stuck float/needle? I pulled the screw at the bottom of the carb that looks like a bowl drain. Got nothing from the top, and fuel from the bottom.<br /><br />My guess is I need to order up a couple carb kits. The carbs havn't been touched in at least 7 years,a nd the boat sits weeks between uses. <br /><br />Anyone want to confirm my suspicions?<br /><br />How hard are these carbs to rebuild? Maybe the better question may be, how hard are they to set and get back in sync?

 

[Solittle]

Re: '76 85hp, suspect carb issue

Jason - Now is the time to get the OMC shop manual that you have always wanted. Rebuilding carbs is not a big deal. They are much simpler than their automotive breathern.<br /><br />Your post is confusing as you say the top two cylinders are not firing yet if you spray seafoam they fire. This does not compute in my small brain.

 

[JasonB]

Re: '76 85hp, suspect carb issue

Sorry SoLittle. I should have phrased that differently. Pulling the plug wires from the top two cylinders does not change anything while it is idling. With them plugged in and spraying seafoam/fuel in the throats, the engines starts running properly. I believe I have good fire, but its like the top carb isn't feeding fuel. I find no restrictions to the fuel getting to the carb as it comes from a T that feeds the bottom as well. The other piece of the puzzle is that I was connected to a tank that hasn't been used in a while, the fuel in it was stabalized, but in hind sight, I should have tossed it as I think it may have been a year old.<br /><br />I have a Clymer manual and have done a few automotive/marine carbs. Making sure the carbs are still in sync is my worry.<br /><br />Anything else I should work on while I'm in there, like fuel pump or anything?

 

[djzyla1980]

Re: '76 85hp, suspect carb issue

Sounds like stuck needle... <br />I'd rebuild carbs... if your sure there fuel comming out the fuel line that connects to the top carb

 

[Solittle]

Re: '76 85hp, suspect carb issue

Last time I did the carbs on one of my 1987 110s I took both carbs off without disconnecting one from the other so did not have to do the sync.

 

[Seamule Captain]

Re: '76 85hp, suspect carb issue

I just rebuilt the carbs on my 74 85hp rude and it was cake. Don't worry about the sync because you can disconnect the linkage without changing any sync adjustments. In fact you can remove them(carbs) and leave both carb links together. Just look at what is connected where and remove as little as possible. I do wonder about the spark though because the timer base has 2 pickups....1 for 1 & 3 and one for 2 & 4. I just went through that whole senario a couple of weeks ago and the carbs didn't do it...it was the base, but now I don't have to worry about the carbs cause they are done! One other thing, if you do do it, replace the floats while you are in there. It's worth it!

 

[JasonB]

Re: '76 85hp, suspect carb issue

Thanks guys. I have two kits on the way. <br /><br />SC, I'm pretty sure I have good spark since the engine picks up when I spray some fuel in the carb, but I could be surprised. I hope that is not the case. Carb kits are a cheap fix, a base isn't.

 

[Seamule Captain]

Re: '76 85hp, suspect carb issue

Ya I started with one coil, then 3 more, then the power pack, then the rectifier, then the killer base and stator. I got a little improvement with each step but the grand poopa was the base. I think it was intermitent anyway which is a killer when your trying to troubleshoot electronics. Anyway the gas milage is 100% better and the performance is outstanding. The only thing I didn't replace was the starter and solinoid! The wife thought I was crazy until I pointed out the cost of a new 90HP! She was thrilled at spending $800!

 

[JasonB]

Re: '76 85hp, suspect carb issue

Just a liuttle update. pulled the carbs off this afternoon and when I pulled the bowl off the top carb to have a look, behold, the float dropped, ,but the needle didn't. Tapped on it a bit and it dropped like it should. May have found my culprit. Will rebuild both carbs o be sure. Anyone familiar with the fuel pump on this motor? Sierra doen't list a kit for it. Anyone know the Mfgr part#?