'84 Johnson - Caution! newbie at work

[spyder9179]

Hello everyone,

I am brand new to the boating world, having just recently purchased a 1973 VIP (Model not known) boat that came with a 1984 35 hp Johnson Seahorse. I've got several issues that I'm working on, some I've figured out, some I haven't. I'll go ahead and put it out there that I know next to nothing about working on motors, but have resolved to do so, mainly 'cause I can't afford to pay somebody every time something goes wrong.

So here we go:

It starts great, idles a little rough - but the main unsolved issue at this point is that the motor bogs down at anything over approximately half-throttle. I can get it to run at the higher throttle, including WOT, by pushing in the key, which, according to what I've found, is the choke, but not a true choke?, and is definitely not good to run that way. Only did that once, just to see if it would make a difference, and it did. Anyway, I've asked two different people that I think know something about motors (definitely more than me) and gotten two different answers, so I figured I'd throw it out here and see what y'all had to say.

Thanks,

Russell

 

[emoney]

Re: '84 Johnson - Caution! newbie at work

Sounds fuel related, now the question remains which part of the fuel system. Most older engines can't handle the new 10% ethanol gas,
so that could be the root of the problem. Start by getting yourself a Service Manual for that specific motor. You'll want to check the fuel pump, clean/rebuild the carbs if that hasn't been done in a while, check and replace if needed the fuel lines all the way from the tank itself to the motor, etc. Is the gas tank built it or portable? Is it venting correctly, etc. etc. etc. None of this is brain surgery, but the manual will save you a lot of time and $$ by showing you how to do some of this work by yourself.

It's always better, imho, to start with a compression test, spark test and then fuel system check anytime you pick up a new-to-you marine engine. If you know the history, that helps, but people aren't always 100% truthful, either, when trying to sell you something.

 

[spyder9179]

Re: '84 Johnson - Caution! newbie at work

Thanks emoney for the response. I put an additive that was supposed to "take care of" any ethanol related problems, but I suppose it could still be part of the problem. I'll get some "real" gas next time and see if that makes any difference. It is a portable tank, and I've got it vented, so I don't think that's the issue. According to the previous owner, it's a relatively new tank as well. I'll follow your suggestions, and see if I can find a service manual and check the fuel-related parts. Then I'll move on to the plugs, which I should probably replace anyway, given that I have no idea when the previous owner last did it.

Thanks again, appreciate the help.

 

[jasper60103]

Re: '84 Johnson - Caution! newbie at work

Yea, it sounds like a fuel restriction. If the motor has setup for a while with gas, its a good possibility the carb got gumbed-up. Cleaning the carb is easy once you learn how. A factory service manual will show you how to clean and rebuild the carb and other engine maintenance. So definitely worth having. I would try ebay. Congrats on the new rig and keep us posted.

FYI. The parts catalog is available online...
http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1984&hp=35

 

[spyder9179]

Re: '84 Johnson - Caution! newbie at work

Ok, things are about to start happenin'. Due to budget constraints and higher priorities, my boat project got postponed a little, but it's finally time to dig in. I have acquired a service manual (actually have 3 different ones, but have finally gotten a model-specific, factory manual), and have ordered and received a carb kit as well as a fuel pump kit. I'm hoping to get started on it tonight, depending on if I can get finished mowing what I started last night (mowing taking priority, due to height and the fact I will be traveling for work all of next week). If I can't get started tonight, then it will definitely happen tomorrow night, because I promised my wife we would go fishing this weekend to help offset the fact I'll be gone for a week. So I want to, at the very least, eliminate some possibilities, if not correct the problem, before taking her back out this weekend.

My question is, and forgive me for my newb-ness, when I replace these gaskets, both in the carb and the fuel pump, do I need to apply something to them, some sort of gasket-dressing, or just install them dry?

 

[Solittle]

Re: '84 Johnson - Caution! newbie at work

Check your manuals for the gasket dressing. The key part of cleaning the carbs is crud in the passages that you don't see. That is why it is important to blow out all passages with compressed air.

 

[spyder9179]

Re: '84 Johnson - Caution! newbie at work

Well, didn't get started tonight, but at least got done with the mowing. This did give me the chance to go over the manual more thoroughly. I didn't see anything in either section (fuel pump & carb) about a gasket dressing. Checked the instructions that came with the fuel pump kit (none came with carb), and nothing was mentioned there either. The only substance I found a reference to was Gel Seal II, to be applied to the threads of a screw. Hope I'm correct in assuming that this means no gasket dressing is necessary

 

[spyder9179]

Re: '84 Johnson - Caution! newbie at work

Don't know why, but out of the blue something reminded me that I never updated this thread with my results. Turns out the culprit was the carb after all. I had it in my head that it probably wasn't, giving that the previous owner claimed he had rebuilt the carb not too long before I bought it, and everything I could see looked squeaky clean (I know, you don't have to say it).

However, after checking almost everything else, I had it resolved in my mind that the problem had to be the high speed jet; figuring he either neglected to check it, or it had gotten clogged again.

Turns out I was wrong again. As it happens, the previous owner DID clean the carb, and did a really good job at it too, but forgot to replace the nozzle gasket (good thing I had the manual, or I wouldn't have known that it was supposed to be there, and just put everything back like it was). Anyway, stuck the gasket back on, threw everything back together, and it now runs at WOT (and all other throttle positions) like a champ.

So I just wanted to update everybody, and say thanks again for all your help. Now if I could just get some time on the water...

 

[jasper60103]

Re: '84 Johnson - Caution! newbie at work

Glad to hear you got it running good. That nozzle gasket is easy to overlook. Thanks for the update.