mid-70's Johnson 85HP won't run in gear

[jdstephwacotx]

I just picked up my very first boat yesterday. It is a 1960 Larson with a mid-70's Johnson 85HP. The guy selling it supposedly cleaned and/or rebuilt the carbs, replaced the water pump impeller, replaced the starter and cleaned the plugs after it had sat up for the last 5 or 6 years.<br /><br />I took it straight to the lake to see what I got myself into. It starts good. It idles good once warm. The engine will rev up good with the 'warm up lever' (I don't know the name of it). Once the arm is down and the engine is warm when you put in in gear it won't die immediately but once you push it all the way down it gurgles the dies. It won't rev with the throttle lever, just the 'warm up lever'. I don't have a tach so I don't know what RPM I'm getting. I am going by sound.<br /><br />It seems to rev better in reverse than in forward. I don't think I am supposed to but if I keep the 'warm up lever' full forward at the same time that I throttle forward I can putter around but as soon as I pull the lever down and push the throttle any further it dies.<br /><br />Any help would be appreciated.

 

[OBJ]

Re: mid-70's Johnson 85HP won't run in gear

Hello jd and welcome to the forums.<br /><br />First thing is to take some compression readings on each cylinder. This will tell ya' right now if you got into something bad. Generally speaking, the higher the compression the better. But more importantly, the compression on each cylinder should be with in 10 to 15% of each other.<br /><br />Check the spark. Spark to each cylinder should jump at least a 7/16" gap with a hot thick white spark.<br /><br />Spark good, time to redo the carbs. What ya' need to do is go to the local John/Rude dealer, get some carb kits and redo the carbs. "He" may have cleaned them out a little, but he probably didn't get to where the trouble is. Best thing to do is disassemble the carbs, soak them in carb cleaner, follow up with shooting choke and carb cleaner through all passages and follow that up with compressed air. <br /><br />If the engine seems to be in good shape with compression and all, consider getting a service manual. It'll help with a lot of question you might have.<br /><br />Keep us posted.....thanks.

 

[jdstephwacotx]

Re: mid-70's Johnson 85HP won't run in gear

Great, thanks. I think I'll start on the carbs right away. I think that he said he put a new kit in each but I know that he said he didn't 'soak' them. I'll do that with the existing parts first, then get the new kits if no help.<br /><br />What is the poor man's way to check the compression?<br /><br />Also, it seems that the throttle handle has an awful lot of play. Being my first boat obviously I don't know for sure but having driven a few they didn't seem to go forward as far. This goes to the 3 o'clock position before even trying to rev and that is where it kills. If neutral is at 12:00 or even 11:00 does that sound too far? Could this be related to the problem at all? There is no 'click' at neutral so I just try to keep it in the middle during start and idle. It clicks into gear long before 3:00 but it doen't try to rev until further down.<br /><br />Thanks again.

 

[OBJ]

Re: mid-70's Johnson 85HP won't run in gear

A compression gage can be had at any auto parts store like NAPA. Get the kind that screws into the spark plug hole.<br /><br />The problem with the throttle pick up may just be an adjustment at the motor where the throttle cable connects. Or, you may need a sync and link which would be explained in a service manual. This adjustment puts the throttle plate pick up in time with the engine timing.<br /><br />Look at the bottom of the page for manuals from iboats. A generic would probably do you OK.

 

[jdstephwacotx]

Re: mid-70's Johnson 85HP won't run in gear

OK, I am a complete nimrod!<br /><br />This is a Mercury motor not a Johnson. I realize that I am now in the wrong discussion group but everything you suggested still applies right?<br /><br />I also noticed that the Mercury discussion group doesn't have near the experienced members that this group does. Do most fuel and fire subjects apply the same to both. I prefer this group from what I've seen browsing all the different posts.

 

[jdstephwacotx]

Re: mid-70's Johnson 85HP won't run in gear

OK, I took things apart enough to see the carbs and I noticed that the little black plastic rod between the carbs was not connected on one end. When he re-installed them he must have missed it.<br /><br />When I put the throttle full forward, only the top carb was opening. I connected it and now both open with full throttle.<br /><br />Could this be my entire problem? I wanted to run it in a trash can but it got dark on me.<br /><br />Thanks for your help.

 

[zj-jeepster]

Re: mid-70's Johnson 85HP won't run in gear

Yeh, I think that could be one of your problems solved. Let us know how you make out <br /><br />.