please help me make my outings stress free!!!

[makeshifty]

My 1977 Johnson 115 v4 cold starts great, and runs very well However.....

After It runs for a while, usually 45 minutes or multiple starts for short trips, I cant get it to start again, unless I remove a spark plug. I first noticed this because I was testing each plug one at a time for spark, when I go to the third plug, it fired up by accident. Every time I've had this problem, if I remove the same plug, it starts right up. If I put the plug back in, it kills the engine. It almost seems like the spark plug is smothering the engine. If I wait for a long time, usually overnight, I can cold start it great with all plugs in. I don't think it has anything to do with flooded carbs as I've experimented extensively with my priming and choking habits on a hot start. My most recent theory, for however little it is worth, is that maybe the exhaust gets so clogged that it chokes the engine.

Any thoughts would be greatly appreciated. As it stands now, I have to assume that I'm staying overnight every time I pull my boat out. This greatly reduces my fun time.


Thanks

 

[bigpoppakdog]

Re: please help me make my outings stress free!!!

How about possibly adjusting the idle screws? Maybe one is set wrong??

Also, when you say you can get it to fire right up removing the one plug does that also mean it will start up right away like this or do you do this like 45 minutes later or the next day? I'm wondering if you have some electrical issues that are arising when the engine gets hot?

 

[jtexas]

Re: please help me make my outings stress free!!!

Is there spark on that cylinder?

What does that plug look like when you take it out? is it clean, oily, carbon-fouled? does it smell like gasoline? does it have any foreign material on it?

Do a compression test and spark test. Instead of using spark plugs, use an inline spark tester (couple bucks at autozone) clipped to the engine block, gap set to 7/16", look for a strong blue flame.

report your results.

btw those spark plug leads are high voltage and prone to arcing to any good ground within reach, which could blow out an ignition component, so use jumper wires to ground 'em to the block whenever the motor is running or cranking.

 

[makeshifty]

Re: please help me make my outings stress free!!!

How about possibly adjusting the idle screws? Maybe one is set wrong??

Also, when you say you can get it to fire right up removing the one plug does that also mean it will start up right away like this or do you do this like 45 minutes later or the next day? I'm wondering if you have some electrical issues that are arising when the engine gets hot?

When the engine is hot or even lukewarm, it won't start. It starts immediately if I remove a specific plug while it's having this issue. If I wait til the next day, I don't have to remove the spark plug to get it to start.

 

[makeshifty]

Re: please help me make my outings stress free!!!

Is there spark on that cylinder?

What does that plug look like when you take it out? is it clean, oily, carbon-fouled? does it smell like gasoline? does it have any foreign material on it?

Do a compression test and spark test. Instead of using spark plugs, use an inline spark tester (couple bucks at autozone) clipped to the engine block, gap set to 7/16", look for a strong blue flame.

report your results.

btw those spark plug leads are high voltage and prone to arcing to any good ground within reach, which could blow out an ignition component, so use jumper wires to ground 'em to the block whenever the motor is running or cranking.

First off, thanks for the advice!
Yes there is spark on that cylinder.
The plug looks a little wet, but I think its a normal amount of gas/oil for a 2 stroke. its black, im not sure if that is carbon. I think it smells a little gassy, but no foreign material.
I will double check the compression, which was good last time i checked, but I'll get a spark tester and get back to you.

 

[jtexas]

Re: please help me make my outings stress free!!!

If the insulator is black (not black with oil, but dry black), that hole is running rich (when it's running). How does that one compare with the others? If the rim and electrode(s) are black with carbon, it needs replacing.

Are you using Champion QL77JC4?

 

[makeshifty]

Re: please help me make my outings stress free!!!

So I just got back from doing my best diagnostics. But first I replaced the fuel filter, lowered my throttle which seemed kinda high, checked the timing and sprayed carb cleaner in the air intake.

I started and ran the engine a few times until it quit starting.
The plugs have a splotchy very thin coat of oily gas, but if you wipe it off, it is black near the electrodes and the arm thing that it arcs to. This seems pretty consistant across all 4 plugs. All plugs are firing blue however, to me it seems like the spark may be weak but I don?t? have much to compare to but it seems less intense than my small honda civic fires. My plugs are champion L77jc4, is that different than QL77JC4?

Now some sad news.
When I did a compression test, I found that half my engine (the same side with the engine killer plug) has lost a bit of compression. When I bought the boat, my mechanic said three cylinders show 125 and one shows 130. Now I?m reading 2 at 120ish and 2 that barley hit 100. Is this tragic or still in normal range?

 

[jtexas]

Re: please help me make my outings stress free!!!

the "Q" series weren't around in the 70's, same plug only shielded against radio interference, recommended for motors with CD ignitions (which yours has). Probably wouldn't switch before they wore out, unless they caused a problem.

Some PSI variance vs your mechanic maybe due to different gauge and maybe different technique (plugs in or out, throttle open or closed, engine warm or cold, etc.) The two at 120 might have not even changed at all. It's 20% difference between the cylinder banks indicates a problem. I assume you repeated the test, just to be sure? I would.

Read the thread on "Decarbing your motor", over in the Engine FAQ section of iboats. They say you can recover some lost compression.

I'd be thinking about pulling the cylinder head on the weak side, for inspection. Hopefully some others will chime in here with opinions.

Just a heads-up, carb cleaner sprayed through the intake can't clean the carbs cause it just goes straight through into the crankcase, where it does what it's designed to do: strip the lubricating oil from the cylinder walls. Generally regarded as a bad idea with 2-strokes.

 

[F_R]

Re: please help me make my outings stress free!!!

Very unusual symptoms, for sure. You need to check to see if you have a 7/16" spark with the plugs in, when it won't start. If you do, it is not the igniton system. But you need to eliminate that possibility before checking everything else under the sun. That compression difference in cylinders raises a bit of concern, but since it starts & runs ok when cold, it probably is insignificant. I really don't think the plugs have anything to do with it. If it were the older model with a two stage choke, I would say Aha! But it isn't, so no prize there.

In other words, I don't have an intelligent answer.

 

[tashasdaddy]

Re: please help me make my outings stress free!!!

OK, jtexas asked me to look at this.

1st which cylinders have what compression.
2 1

4 3
this configuration.

it is wild shot, but could be a blown head gasket, or warped head, on one bank, allowing water intrusion, hydro- locking the cylinder. also could be a carb doing the same thing.

as said, spraying Carb Cleaner is a total waste of time and cleaner, can do more damage than good.

carbs must be remove, opened jets remove and all throughly clean, reassembly with carb kits.

also spark test with an adjustable test is a must.

fully charged battery, and good battery cables, clean connections, are a must, as that starter has to turn the engine +- 300 RPMS for the motor to start.

choke should not be necessary on a warm engine.

 

[makeshifty]

Re: please help me make my outings stress free!!!

Thanks tashasdaddy. I think you might be on to something with the starting rpm?s.
Sorry for the slow response here, I forgot to bring my compression tester to the boat last Friday and I?m finding more and more problems.
So on Friday I replaced the remainder of the gas in my tank with fresh well mixed gas. The engine usually only works for about half a day, but this weekend it ran great Friday through Sunday morning. Of course when it was time to go home, it wouldn?t cold start. Maybe that rules out heat related issues. After much cranking, I pulled out the same plug, and it fired up immediately. I put the plug back in and it wouldn?t start. I noticed that engine was turning over slower as the battery was getting low. I pulled the plug out again and noticed that the engine cranks faster, and again it fired up rapidly. I?ve always assumed removing the plug was introducing much needed air to the cylinders or expelling excess gas to help it start, but now I?m wondering if the ignition is weak and it doesn?t always reach the correct rpm. To add to this theory, I then hooked up my backup battery. The engine cranked much faster and started right up with all plugs in. Is there a way, sans tachometer, to test for 300 rpm?s while starting?
On my way back to the dock, I tested the dc voltage of the engine battery cables. I was only getting 12.5. Maybe the stator has gone bad, or some voltage regulator or something. Last time I checked the engine voltage (while in motion) I was reading 18+ volts. How do I troubleshoot this one?
Now to the diagnostics with tools I had on hand today.
I noticed a chewed up looking wire coming out of the rectifier. What does a rectifier do? Anyway to test if it works, despite its ugly looks?
I?m not sure which numbers correspond to which sparkplugs except for #1, which I discovered while adjusting the timing. I?ll list them in order of how they physically appear when looking at the back of the engine
Cold compression
115 100 (this is magic cylinder #1 that makes the engine run when I pull its sparkplug)
power pack
115 105
propeller
Hot compression
105 95- on first crank the engine accidently fired up showing 155 pounds of pressure
110 95
When I got this engine, my mechanic did a compression test , I?m not sure which cylinder is which, but it was written like this.
125 125
125 130

Timing
I don?t have a tachometer to adjust the timing perfectly but I set it at 28 degrees when throttle is just forward enough to make and the timing bar that goes under the fly wheel touch the spark advance set screw.
Also, last but not least, per your guys? recommendation I purchased an inline spark tester, and realized that coil #4? (bottom left side) has an intermittent connection on the plug wire itself. It was slipping out of the coil. I squeezed it back in, but I?m yet to see if that was a proper fix or not.
I?m starting to feel like I have a big mess on my hands.... Any other thoughts or ideas are greatly appreciated!

 

[ksubigbuck]

Re: please help me make my outings stress free!!!

I have the exact same motor. It might be a pain but you WILL get it to run well. I'd do whatever these guys tell you to do. Starting with making sure your cranking battery is providing plenty of power. Also make sure all of the connections to your starter solenoid and starter itself are clean and tight. This will ensure that all of the battery's power is actually making it to the starter.

Good luck!

 

[trendsetter240]

Re: please help me make my outings stress free!!!

Cold compression
115 100 (this is magic cylinder #1 that makes the engine run when I pull its sparkplug)
power pack
115 105
propeller
Hot compression
105 95- on first crank the engine accidently fired up showing 155 pounds of pressure
110 95
When I got this engine, my mechanic did a compression test , I?m not sure which cylinder is which, but it was written like this.
125 125
125 130

You should remove all plugs while performing a compression check to get an accurate reading. Otherwise problems with another cylinder might affect the readings of the cylinder being tested.

 

[trendsetter240]

Re: please help me make my outings stress free!!!

After reading all these posts I'm inclined to go with tashasdaddys idea. You may have a blown gasket or warped head on the side where the removed plug lets the engine start.

Could be that water and/or air is seeping into the cylinder causing it to not start.

I'd pull that head and inspect the gasket and check the head for flatness with a straight edge.

 

[makeshifty]

Re: please help me make my outings stress free!!!

I have the exact same motor. It might be a pain but you WILL get it to run well. I'd do whatever these guys tell you to do. Starting with making sure your cranking battery is providing plenty of power. Also make sure all of the connections to your starter solenoid and starter itself are clean and tight. This will ensure that all of the battery's power is actually making it to the starter.

Good luck!

LOL! Thanks for the moral support! I need that right about now. I spent almost all last year salvaging parts and materials to build this boat. It's a small no frills house boat, or more like a chicken coop really. Just finished it this April and I've had nothing but engine problems... I was supposed to be like Tom Sawyer by now. Instead, I'm chasing ghosts around my engine!

 

[makeshifty]

Re: please help me make my outings stress free!!!

After reading all these posts I'm inclined to go with tashasdaddys idea. You may have a blown gasket or warped head on the side where the removed plug lets the engine start.

Could be that water and/or air is seeping into the cylinder causing it to not start.

I'd pull that head and inspect the gasket and check the head for flatness with a straight edge.

Thanks for the info! I'll re check the compression tonight, with no plugs in.
As far as removing the head...... I better rule out a few smaller things first. I'm quite handy but I'm learning mechanics through trial and error, and my repair manual is a little over my head. I'm hoping it doesn't get that far, even thought that's a likely culprit.

 

[makeshifty]

Re: please help me make my outings stress free!!!

You should remove all plugs while performing a compression check to get an accurate reading. Otherwise problems with another cylinder might affect the readings of the cylinder being tested.

This method gave me 0 psi on all cylinders....?

 

[trendsetter240]

Re: please help me make my outings stress free!!!

This method gave me 0 psi on all cylinders....?

Seriously? I think you may be missing something. If not then both heads are not sealed between the plug holes.

I've never seen that.

 

[makeshifty]

Re: please help me make my outings stress free!!!

You did mean remove all spark plugs, not just the wires?
I can try again, but I don't know what I couldv'e missed. Maybe the pressure gauge is faulty.