Johnson 25 hp fouling bottom plug...

[Subtle]

Hello, my name is Greg I'm pretty new to the forum. I have a 1992 Johnson outboard 25 hp model number J25REND. I paid $700 for this piece of junk and have taken it out two times of which I had to row my self back in. The guy I got it from said I'd get years of enjoyment out of this engine and so far none. The first time I went out the kill switch decided to shut me down and it wasn't until I unplugged it that I was able to start it again. So I fixed that. The second time. I trolled a little bit and now my bottom cylinder plug is fouling at idle. I have searched the interwebs and found that it is either the thermostat or the question goes unanswered. I have pulled my tstat and put it in a pan on the stove top and it opened. And I would assume at the right temperature as well because it opened before the water boiled and I hear these tstats run colder. Never the less it does function. I'm starting to think it's a carb or primer issue. My motor has the manual primer. I'd like to know if there is anyway to check to see if it's bad.

Other things I've done in this process.
I have a 2 Johnson 275s which run the same plug and coil.
So I've done some swapping around with that. Same issues.
I have also set my carb back to the 1 3/4 turns that was told to me in the base line starting.
I have also checked compression and got 110 which I have heard a lot of bs about. Some one told me that the actual number doesn't matter as long as the cylinders are the same and someone else told me it's way to low.
I believe the first one is correct. But what do I know I'm a auto mechanic not a outboard mechanic.

Thanks.

 

[Bosunsmate]

Stick with it, those compression numbers seem good, similar readings is most important.
Now for the fouling- Does the primer bulb hold firm with engine off?
Have you tried a spark test?

 

[Bosunsmate]

To check if its your primer, just unplug the end that comes of the plunger housin (the hose that goes to the carbs) that way the motor wont lean out from sucking on air

 

[Bosunsmate]

To check if its your primer, just unplug the end that comes of the plunger housin (the hose that goes to the carbs) that way the motor wont lean out from sucking on air

 

[Bosunsmate]

To check if its your primer, just unplug the end that comes of the plunger housin (the hose that goes to the carbs) that way the motor wont lean out from sucking on air

 

[Subtle]

How long should the primer bulb hold firm, I drained all the gas out of it a few days ago, and upon doing this I noticed a rattling sound inside of it, so my father in-law took it apart and we saw that one of the check valves had come loose the engine side, so we put it back together and shorted my hose and reinstalled. well a couple days later i noticed a piece on my garage floor. i guess they have check valves in both sides, and the tank side is missing... so I wanted to buy another one of those.

As for the primer mine has two ends, both of which go to the carb, one to the fuel bowl and the other to the carb throat.

I noticed something funny yesterday, I will try to post a picture and comment on it today.

 

[Subtle]

I give up. I messed with it all last night. I even pulled the flywheel because I thought a magnet might have moved but as it would turn out the magnets on this engine can't move. I'm just going to take it in.

I also want to say that I have spark on both cylinders, my plugs are saturated and my compression is at 110. The only thing I can come up with is two much fuel. However after it idles super ****ty and then stalls it won't fire back up until I prime it again.

Also I know that these engines fuel pumps run off the bottom cylinder so I bought a fuel pump rebuild kit but haven't installed it yet because I was told that if it was the problem there would be fuel in the pulse fitting and I don't have any there.

Thanks for all help.

 

[Bosunsmate]

primer should hold firm for at least thirty seconds, mine does for an hour.
So both plugs are wet now?
Have you check timing?

 

[Subtle]

I don't know how to do that on these, is there some sort of guide, and if it was the timing wouldn't they at-least both be firing? Also isn't this one fixed timing?

 

[racerone]

The timing changes as the plate under the flywheel rotates.----It is set at the factory and rarely needs adjustment.-----Plugs foul because there is not enuff heat produced in the cylinder to keep them clean.---Have you looked into inspecting the lower crankshaft seal.?------Have you inspected reed valves ?----Have you run with a timing light on the bottom cylinder to check spark quality as you run the motor ?

 

[Bosunsmate]

I don't know how to do that on these, is there some sort of guide, and if it was the timing wouldn't they at-least both be firing? Also isn't this one fixed timing?

Im not sure what the current findings are, is that they are both wet, but the bottom one isnt firing?
If your powerpack is failing timing can go out and you can have intermittent spark, i use a timing light to check that, it can also be the stator.
In question two i asked if you did a spark test, not sure youve answered that

 

[Subtle]

i have read stuff on the crankseal. I'm really starting to think that is my problem... I just dont understand how the system works. I have read that you can have compression and a bad seal and this will cause the engine not to fire. which doesnt make sense to me because I was taught compression, fuel and fire makes a bang... and i have those three things, please correct me if i am wrong. Thanks.

As to the last reply. My lastest findings are that both are actually wet and the bottom is not firing. I pulled the flywheel I put a brand new spark tester on there and I could barely see the spark in the thing. but i have never used one of them before so i hooked it to my car and man what a differance that made. Is it possible that my powerpack is bad... I mean the spark tester was super bright on a car but not on the engine, and also on the engine both wires were sparking... Thanks.

 

[racerone]

On a two stroke like yours you need 4 things for the engine to run.---Compression ---spark----fuel..----The 4th one is misunderstood and it is crankcase compression .-Poor or no crankcase compression means that fresh fuel is not transferred to the cylinder.--Thus you have poor running condition.--Testing compression in the cylinder does not mean you have compression in the 2 crankcases on a motor like yours.----Crankcase compression and cylinder compression are totally seperate things.--You can have good crankase compression and no cylinder compression.--And you can have poor crankcase compression with just excellent cylinder compression.-----This is why many folks are so confused when trouble shooting the motor.---There are some videos posted on u-tube about this .--Some better than others.-------The only spark test I use is an open air gap of 7/16" or so.-----If spark does not jump that gap the magneto needs work of some sort.----Fancy glow tubes and other gadgets are not needed.

 

[pro-crastinator]

Regarding "reed valve" 2 stroke engines (which is the flavor we talk about daily) -
The way it was explained to me, the "crankcase compression" is made possible by the reed valves. I have never heard it expressed that way -

It was 1 of 2 conditions. Either the reed valves were working- or they were not.
If there were a total reed valve failure, I would think there would be fuel blown back toward the carb.
Not sure what the symptoms would be for a partial "wore plum out" condition.

However, now that I have clouded up the water, I will repeat the advice I was given when I expressed concern over my reed valves condition.
I was told that reed valve failure is very rare.

 

[Subtle]

So, I need to be able to jump a 7/16 gap and if I can not do so then I need to look at coils or my pickup? I did do the glow tube test. horrible test IMO. I called the shop to price out all the stuff to do the seal because thats really where im at on all of it, and he said that if it was the seal then that one cylinder would be running lean not rich... but just because i have fuel on the plug doesnt mean that its rich it could mean that its just not firing... correct?

 

[Subtle]

is there anyway to test the seal before i tear it all down?

 

[Bosunsmate]

is there anyway to test the seal before i tear it all down?

DONT TEAR IT DOWN, i very much doubt that is your problem.

 

[Bosunsmate]

If the lower seal is busted you wont get crankcase compression and therefore fuel would never make it to your lower plug and make it wet.

Do this,
1) run the outboard and then remove the wet plugs. Light the wetness, if it does not go poof then it is wet with fuel and water. This happens a lot and is caused by a exhaust gasket leak in most instances.

2)Next do a spark test by jumping a 7/16 gap. If it does not do that on both cylinders then report back and we can go from there.

Once you report back on 1 and 2 then it will be clear what is wrong. DO NOT GET SIDETRACKED AGAIN otherwise you will spend big bucks which if you are like me means less to spend on the ladies

 

[Bosunsmate]

You can make a cheap spark tester by putting two nails 7 16 apart and attaching a spare HT wire to it and then back to the sparkplug.
Ive no idea what a glow one is you are mentioning but since you are saying that it sparked on your car but not on your boat i suspect that that is very much your problem.
Most likely the stator, but hold your horses do the test 1 and two above and then we can tell you how to test stator

 

[Subtle]

DONT TEAR IT DOWN, i very much doubt that is your problem.

Turns out you'd be right... I tore it down and replaced it, it wasn't the problem, +1 for you!