1987 johnson 55hp commercial HELP!!!

[elfelt]

Ok, this is post #1 for me! I need some major help!
I have a 1987 55hp Johnson commercial that was running rough and bogging down at the end of last year. It is an intermittent problem that doesn't seem to be effected by temp, runtime, or anything else really... but when it runs well (60% of the time) it runs great!

​Symptoms:
Idles great! revs in neutral, but as soon as it is under load it will not increase in rpms and goes very slow. (5mph) I can run it on the muffs and it sounds great! revs in neutral, reverse and forward...

It trolls rough if at all, reverse or forward doesn't make a difference.

I have good spark on both cylinders while cranking (haven't checked while running under load)

carbs look clean but I have not taken apart yet

gas tank may need replacing, its an old metal tank with a new hose and fittings, but it works fine on other outboards sooo...

Primer ball stays "hard-ish" with problem is happening and choking the motor has no effect on rpm when the problem is going on, BUT when the motor is running well a full choke will kill it.

I noticed a pretty high amount of black oily gunk coating the outside of the shaft of the motor, from the base of the powerhead do to the lower unit...and there are some globs of blue/black sticky (a little firmer than grease) in the housing of the motor.

​My best guess: bad reed valves...
The gasket for the air-box shroud (not sure if that's the name) had a tear, so I'm thinking that maybe if I have bad reed valves there is unburnt fuel coming back through the air box and leaking into the motor housing, causing it to leak down the shaft.

​Thoughts?

 

[flyingscott]

Do a compression test and make sure spark jump 7/16" air gap. And revving the motor on muffs does not mean anything and can cause damage. Unburned fuel in the air box is normal.

 

[juno pierrat]

basic starting point, compression test, please post numbers, and does spark jump 7/16in. open air gap?, while running use a timming light to see spark is constant,
intermittent problem sounds more electrical, reeds are mechanical and i would think be constant problem

 

[ondarvr]

As mentioned, check the compression.

​Reeds don't often go bad, not that they can't, it's just not common.

You can't tell anything about a carb from looking at the outside, all the important parts are inside.

What it does in neutral doesn't mean much, it can have severe problems and still sound OK.

Good spark when cranking goes along with what it does in neutral, it doesn't mean much, electrical components tend to first fail intermittently when under stress, so check it with a timing light or spark check tool when it's acting up.

 

[oldboat1]

As mentioned, compression, spark, and test for dropped cylinder under load.

But if those check out, I would do full carb cleaning and rebuilding -- disassembly and soaking. I leave the linkages in place along with jets as the jets are easily damaged. Remove the domed plugs before soaking. Finish with carb spray in all openings. The OEM kits may come with parts diagrams, and those are helpful -- good idea to do one carb at a time so you have the second one for comparison.

 

[elfelt]

Ok! sounds like I have some work to do after it quits snowing! Living in MN is kinda limiting when your working outside. Can I get an accurate compression reading by pulling it over rather than cranking with the key? I will post numbers tmr, if I can get my hands on a compression tester.
​Thanks!

 

[ondarvr]

It will typically read lower when trying to pull start it.

 

[oldboat1]

yup. Pull both plugs, and key crank until the needle stops rising. Keep the boots away from the open plug holes!

[ed. snow here in NY for the next three days....]

 

[flyingscott]

Pull the tether switch that will kill the spark when doing the compression test.

 

[elfelt]

update...
​I decided to clean the carbs (which were incredibly clean) and I found that a plug "not sure what its called but the little metal disk that is pushed one of the two holes inside the carb next to the needle" was in the bottom of the bowl on my bottom carb.

The carbs are rebuilt with a oem kit and they are back on the motor. BUT, I don't see any idle adjustment screws, (like a atv or dirt bike carb) could it be that they are fixed, or internal?

​I also cleaned the housing of the motor and got rid of all the oil residue so I can see a leak when I fire it up today. I am thinking that the manual primer may be the cause of the leaking fuel. Has anyone else had issues with these primers? or know of a way to test them???...at $103.99 I'm not in a hurry to replace lol

​I got my hands on a timing light and compression tester, I will put it on the muffs today and see how it runs... or if it runs after I messed with the carbs hwell:

THANKS!

​

 

[flyingscott]

Need the model #. The primer, if it still clicks the main body is probably good. The plastic housing on top of the primer is replaceable as a separate unit.

 

[racerone]

Is this the manual primer pump or the electric valve primer with the red lever ??------Was this a manual start model converted to electric start ?

 

[interalian]

update...
​I decided to clean the carbs (which were incredibly clean) and I found that a plug "not sure what its called but the little metal disk that is pushed one of the two holes inside the carb next to the needle" was in the bottom of the bowl on my bottom carb.

The carbs are rebuilt with a oem kit and they are back on the motor. BUT, I don't see any idle adjustment screws, (like a atv or dirt bike carb) could it be that they are fixed, or internal?

​I also cleaned the housing of the motor and got rid of all the oil residue so I can see a leak when I fire it up today. I am thinking that the manual primer may be the cause of the leaking fuel. Has anyone else had issues with these primers? or know of a way to test them???...at $103.99 I'm not in a hurry to replace lol

​I got my hands on a timing light and compression tester, I will put it on the muffs today and see how it runs... or if it runs after I messed with the carbs hwell:

THANKS!

​

Core plug that covers the idle ports? If that was off, you'd get no idle fuel flow on that throat. Surely would cause a rotten idle.

 

[elfelt]

racerone: manual primer, its about the size of a shotgun shell and it has a pull lever that sticks out of the bottom front left (as you are in the boat)
​flyingscott: cj55rslp is the motor #

​I just ran it on the muffs for 10 mins, starts up great with just a feather on the throttle but as soon as I take it back to idle it dies. It has never done this... I fixed one problem but created another!

 

[racerone]

I know what the manual primer looks like ----Did this problem show up suddenly ?---When did it last run properly ?--Have you checked the flywheel key ?----What are the compression numbers ?-----Does spark jump a gap of 7/16" on both leads , yes or no ?----Need that information first.

 

[elfelt]

I am not familiar with the flywheel key... spark will jump 7/16, I haven't done a comp. test
The problem of bogging down under load showed up last year.

I ran it today on the trailer, I just backed it into the water so I could get more backpressure... and it idled great! It would still bog down under load....BUT if I put my hands over the throat of the carb it would pick back up and run well! SO...I think I have narrowed it down to a fuel issue I am going to tear into the fuel pump/diaphragm tmr and see...

 

[ondarvr]

To test the fuel pump all you need to do is squeeze the primer bulb while it's bogging, it will start running better if the fuel pump or an air leak is the problem, but what you've described so far wouldn't lead me to a fuel pump.