1986 Johnson 30 Power

[perwel]

Just recently (in the last year) I'm having trouble with the overall speed of my boat. It seems to not have the speed it used to. Nothing physically has changed - weight, # occupants, etc. The engine just never seems to "open up" to top speed. Estimated speed loss is 5 mph and diffculty getting the boat to plane as easily as it once did. Is this an indication of something that has or is failing. The only work done on the engine, other than basic maintenace, is a new power pack (2001) and a carburator kit (2009). Any help would be great!

Thanks

 

[Big flop]

Re: 1986 Johnson 30 Power

Did it sit for any length of time?
If it did the carb could be varnished.
Our gas we buy now can start to varnish
in two months.
Has it been a while since it's last
service ?

 

[perwel]

Re: 1986 Johnson 30 Power

Just over the winters. Used regularly in the summer. Winterized each fall and stored inside 100% of the time.

 

[Daviet]

Re: 1986 Johnson 30 Power

You need to start with some basic checks, compression, spark and fuel delivery.

 

[perwel]

Re: 1986 Johnson 30 Power

I hope I'm doing something wrong. I've never checked compression or for spark before. I bought a spark tester and followed the directions. There is a blue-tipped spark that shoots between the tips of the tester. Between the tips of the tester the spark changes from blue to orange and then blue again. The same for both. Not sure if this is good or bad.

Started the engine in preparation for compression testing. Motor started right away and let it run for 10-minutes to warm up. I proceeded to shut down the motor, remove the plugs, screw in the compression gauge and turn the engine over (electric start). No pressure detected from either. The gauge never budged. Am I doing something wrong?

Thanks for your patience with me.

 

[Daviet]

Re: 1986 Johnson 30 Power

What was the size of the air gap on the tester, should jump a 7/16" gap and be bright blue.
If the engine run to warm it up, you have to have compression, check it cold. There must be something wrong with the compression tester.

 

[larryg]

Re: 1986 Johnson 30 Power

did u set the spark tester at 7/16.if there is blue spark in that distance on both its good.as far as compression,should have been some kind of reading,everything screw in properly,hole in line?

 

[perwel]

Re: 1986 Johnson 30 Power

Just retested the spark. Beautiful blue lightning-like spark across the 7/16" opening for both. I agree there must be a problem with the compression tester. Just inspected it thoroughly but still doesn't repond at all. Since the engine is running to warm up does that mean I have enough compression?

Put new plugs in the engine. Could that have been the problem with my lack of power? Do you believe the varnishing suggestion is something to be dealt with? Trying to get this engine in as good of condition as I can with the focus on maximizing the power to where it once was. I'm willing to put a couple bucks in it if you have suggestions along the lines of improvements.

Thanks again

 

[Daviet]

Re: 1986 Johnson 30 Power

If it runs it has enough compression to start, but could have low compression on one cylinder that could cause problems. You could use an inductive timing light and make sure you are not loosing spark at high speed. You might want to check your high speed jet is not restricted, not allowing enough fuel at high speed. You could try squirting some fuel mixture into the carb at high speed and see if it runs faster, if so you have a fuel problem, carb or fuel pump.

 

[perwel]

Re: 1986 Johnson 30 Power

What does the fuel pump look like and is it easy enough to check if it's working properly? Can you help me find the location of the high speed jet so I can check it?

Thanks

 

[Daviet]

Re: 1986 Johnson 30 Power

#19 is the high speed jet, it takes a special tool to remove it. You could try running a piece of soft copper wire through it while it is still installed. If that helps you will need to remove the carb and clean it properly.
http://www.ishopmarine.com/ishop/js...nown&isFrPG=false&forItemCode=&pCode=C0053803
Here is your fuel pump, remove the hose going to the carb, spin the engine over and see if it is pumping fuel. You will need to test it at high speed, pump the primer bulb at high speed and see if the engine picks up, if so you need to replace/overhaul the pump.
http://www.ishopmarine.com/ishop/js...nown&isFrPG=false&forItemCode=&pCode=C0053810

 

[larryg]

Re: 1986 Johnson 30 Power

bread tie wrap does a good job with plastic off it ,running it thru the jet,then spray carb cleaner thru it. fuel pump:Leave the hoses attached to the fuel pump. Remove only the two screws that attach the fuel pump to the powerhead. Re-insert those two screws and install a nut to each of them so that the fuel pump is securely clamped together. With the fuel line attached to the engine, pump the primer bulb while observing the pressure/vacuum operating hole on the back side of the fuel pump. Should any fuel leak out that hole, the diaphragm is faulty

 

[perwel]

Re: 1986 Johnson 30 Power

Thanks guys. I'll have a look at both tonight.

 

[perwel]

Re: 1986 Johnson 30 Power

Just checked the fuel pump by leaving the gas line attached and secured the pump sections together using two nuts on the end of the mounting screws. Using the primer bulb, I pumped gas into the fuel pump without diaphram leakage. Then I removed the fuel line to the high speed jet to make sure it's clear. Out came a significant stream of fuel which suggests to me it is. In a message presented in the forum as a different thread, you guys have helped me realized that I have a broken (shattered) throttle plate in the handle of the motor. It's affecting my slow speed adjustment for sure. Might this be the root cause of my overall compliant about reduced power? I still need to check compression.

Thanks again.

 

[larryg]

Re: 1986 Johnson 30 Power

how is the burgh,i use to live there.fuel may have come out alot,but the jet may still have something in it.take the carb off and clean it thoroughly.then if it still does it,that isnt the problem.i had picked up a joh.20 and had problems with it also,such as the problem you have.start with the carb,put a clear line on pump to carb,to see if fuel is flowing ok.blow out all fuel lines,to make sure they are clear.when is the last time they were replaced.while you have carb off take off intake manifold,behind this is 2 sets of reeds.make sure they are not broke .private message me if you need any more info.i have a manual i could send it to you if you need it.

 

[perwel]

Re: 1986 Johnson 30 Power

Finally was able to test compression. Top is 60 and bottom is 100, electric start. Tested cold. Good spark and fuel flow

 

[Daviet]

Re: 1986 Johnson 30 Power

I think you may have found your problem.

 

[perwel]

Re: 1986 Johnson 30 Power

What's the diagnosis and what do I need to do?

Thanks

 

[Daviet]

Re: 1986 Johnson 30 Power

With 40 lbs difference in compression, you have a problem. You might try a real good decarb and see if the compression comes up any. Might have a head gasket problem, leaking.
Did you check the high speed jet, is it clear?

 

[perwel]

Re: 1986 Johnson 30 Power

Stuck a piece of wire (stripped bread tie) through the high speed jet. It seems clear. After checking fuel pump operation lots of fuel ran out of high speed jet. A carb kit was installed last year to include new fuel lines all the way around. Carb was clean as a whistle. Head gasket was also blown last year but replaced (as far as I know based on what the tech told me). I'm happy to replace it again if it makes sense. Should I focus on the head gasket since the carb was redone and high speed jet was clear?