1980 Johnson 175 not getting on plane

[sccole]

I can't get the boat to plane out, yesterday I found a loose carb and tightened it up and motor sounded really good while hooked up to muffs, today I tried it on the lake, and though it ran better than day before, when throttling up it hesitates and then goes faster but will not get on plane. I was running on a portable tank and also on the built-in tank and ran the same. also is there a kit available to rebuild the binnacle or would I need to buy a new one.

 

[Texasmark]

Re: 1980 Johnson 175 not getting on plane

I'm hearing inadequate fuel supply (air too in the correct ratio....roughly 12:1).<br /><br />Anything that will limit your fuel delivery is suspect. It won't run good on muffs if there is something wrong with it......other than inadequate fuel to do the work required when on the boat. If you changed tanks then the problem is internal....Easy check is to get someone to squeeze the bulb when trying to get up. If that solves your problem get a fuel pump or change your fuel filter.....to name a couple of reasons.<br /><br />Mark

 

[R.Johnson]

Re: 1980 Johnson 175 not getting on plane

I would do a compression, and spark test to start with. If that checked out, I would go to a pressure, vacuam test on the fuel system. Did you use the same fuel hose, primer bulb on both test's? If so, shake that primer bulb, and see if you can hear a rattle. One of the check valve's may have come apart.

 

[sccole]

Re: 1980 Johnson 175 not getting on plane

I took apart the carbs and cleaned them and replaced all fuel lines inside the motor cover, took for a test run and did run better, was able to get it running up to 15 mph. When at full throttle I could hit the primer on the key switch and it would help some, but at lower speeds it would cutout as it should. I am going to do a compression and spark test within a couple of days. I am thinking about rebuilding the fuel pumps while I am waiting to get the compression test. Anything else I can have overlooked?

 

[sccole]

Re: 1980 Johnson 175 not getting on plane

bump

 

[Silvertip]

Re: 1980 Johnson 175 not getting on plane

You need to begin with all the basics. Make sure you have good spark on all cylinders. It sounds like one or more cylinders are not firing (even though it may sound ok on muffs). Compression and spark tests are mandatory. Although you say you cleaned the carbs, did you totally disassemble them, give them a good soak in carb cleaner, and then blow out all passages with compressed air? Then they must be assembled using new kits making sure float level is properly set. When done, a link&sync is necessary followed by idle mixture and idle speed adjustment with the engine in the water -- not on muffs (no back pressure on muffs).