85 Johnson 115 just won't idle. I've gone through EVERYTHING!

[brew0688]

Hi Everyone.

I'm new to the forum, though I've been taking advantage of the wealth of knowledge on here for some length of time.

Here is my situation. Please please, can somebody know what is wrong with my motor. I'm not ready to pay $109.00 an hour for marina labor. :-/ (broke college student).

So a little over a month ago, I bought an old crappy boat with a 115hp johnson on it. I just wanted to take the motor off to put on my 20ft center console.

On my boat, I used to have an 85 johnson 75hp. It was way underpowered, which is why I got this 115. The wiring was all the same, so it seemed plug and play. Tilt / trim works great. Starter works just fine. Nothing seems amiss in terms of hooking it up to the controls.

Now the nitty gritty:

When I first got the motor, it wouldn't do anything. Turned out the starter was bad. Got a new one. Then it would turn over, but not run, so I opened the airbox to find a huge wasp mud nest. Cleaned that out, and tried again.... The motor ran for a few seconds at a time, but very roughly, and would splutter and die. I ordered carb rebuild kits, and put them in. Adjusted the floats perfectly. Then, figured out the VRO pump wasn't working (The oil side had been disconnected and I was running 50:1 as most advise with older VRO pumps). Didn't take long to see it wasn't pumping fuel. The diaphragm looked old and was very rough. After realizing a new VRO pump is 340 bucks, I read on this forum I could replace it with a similar fuel only diaphragm pump (part number 0383765), which I ordered and mounted.

So far, new starter, new carbs, new fuel pump. New plugs and leads. All new fuel / vac hoses and lines. The reed valves look good. Good compression - 115ish in all 4 cylinders.

The timing doesn't seem too far out, and no matter how I adjust it, this thing just WILL NOT IDLE.

The motor runs for a few seconds.. maybe 30 at the most, and then all of a sudden, BOOM. Stops. It doesn't splutter as though it's running out of fuel. It dies as if someone has just turned off the key. Sudden and instant.

Should I rule out fuel delivery as a potential problem? the fuel filter is ALWAYS full of fuel. The pump I installed is brand new and pumping well.

Do I start looking for electrical problems?

Please help. I really want to get this thing out on the water. :-/

Thanks in advance everyone.

Brett

 

[Daviet]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Some things to think about.
It takes three things to make your engine run, compression, spark and fuel.
You say the compression is ok.
Have you checked spark, bright blue flame, jump a 7/16 gap with a snap sound?
You overhauled the carbs, did you remove the idle orifices and make sure they are clean?
Let us know.

 

[brew0688]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Some things to think about.
It takes three things to make your engine run, compression, spark and fuel.
You say the compression is ok.
Have you checked spark, bright blue flame, jump a 7/16 gap with a snap sound?
You overhauled the carbs, did you remove the idle orifices and make sure they are clean?
Let us know.

Thanks for the reply.

Compression is good, yes.

I've removed each plug, and grounded it against the block while turning the motor over. Every plug fires a bright blue spark. All gaps set to 030.

Every orifice on those carbs is absolutely impeccable. I've cleaned them inside and out, 3 times.

 

[Bob_VT]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

If it was a fuel issue it would stumble and die........ electrical issues usually kill a motor like it was turned off.

However....... a 30 second idle is as if it is running only on the primer circuit. If you hit the choke (actually just injects fuel into the carbs) will it keep running? How is your fuel pump working?

 

[brew0688]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

If it was a fuel issue it would stumble and die........ electrical issues usually kill a motor like it was turned off.

However....... a 30 second idle is as if it is running only on the primer circuit. If you hit the choke (actually just injects fuel into the carbs) will it keep running? How is your fuel pump working?

I'm so confused right now, I just want to set fire to this thing. :-/

Today, I attempted to rule out some more issues. I'm trying to decide if it's electrical, or fuel. To test the fuel pump, I disconnected the lead that goes into the choke, and started it up. It built up pressure which I'm sure would have to be adequate to fill the carb bowls.

What seems to be happening, is that the fuel pump is getting fuel into the carbs, but it's just not making it into the cylinders. (I know you want to say recheck the carbs, but I've checked them 3 times. I know they're right.)

Is it possible that my reed valves are badly worn, and that there just isn't enough of a vacuum to pull the fuel/air mixture through? I used a small led light to look through the carbs at the reed valves. They seem to be seating perfectly... but I'm not sure what exactly to look for.

The motor just doesn't seem to be getting gas.

:-/

 

[Daviet]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Are your float levels set correctly.
Spray some gas/oil mixture in the carbs and if engine starts, it has got to be a fuel delivery problem.

 

[classicevinrude]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

You say the motor dies with a BOOM. Is that just a figure of speech or is that a description of what it is doing? If it sneezes out and dies violently it sounds like it is dying lean (no getting fuel). Best of luck to you. From one college student to another!

 

[brew0688]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Are your float levels set correctly.
Spray some gas/oil mixture in the carbs and if engine starts, it has got to be a fuel delivery problem.

After doing some research earlier this week, I decided to check the float levels. They're both perfectly parallel with the carb body when inverted. This is correct, right?

 

[brew0688]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

You say the motor dies with a BOOM. Is that just a figure of speech or is that a description of what it is doing? If it sneezes out and dies violently it sounds like it is dying lean (no getting fuel). Best of luck to you. From one college student to another!

Figure of speech, sir. I'd say it sneezes and dies out violently.

Thanks. What college, what degree man?

 

[classicevinrude]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

If it is sneezing out and dying violently then it sounds like fuel or lack there of may be the cause of your troubles.

I am a Junior at State University of New York (SUNY) at Oswego majoring in Technology Education. How about you?

 

[brew0688]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

If it is sneezing out and dying violently then it sounds like fuel or lack there of may be the cause of your troubles.

I am a Junior at State University of New York (SUNY) at Oswego majoring in Technology Education. How about you?

Yeah. I'm not sure what to think though. I by passed the fuel pump completely, just manually pumped the bulb to keep the carb bowls full at all times. The motor still does the same thing. It's as though the motor isn't creating enough suction to pull the mixture through the carbs. I'm getting to my last legs here. If this thing hasn't made some progress by this afternoon, I'm taking it to a marina.

I have one semester left in a R.N program down here on the west coast of Florida. Can't wait to be done.

 

[spicoastie]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Go get a timing light and shine in the carbs while running, that will tell you if your engine is acutally pulling fuel from the carbs.

Dont know if you have a harbor frieght around but they are like 10 bucks there.

 

[kenmyfam]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Easy fuel pump output test.
Remove the fuel pump to carb's hose at the pump.
Connect a temporary length of hose to the pump outlet.
Get a container to catch fuel.
Put muffs on if not in the water to save the impeller.
Pull lanyard or remove plugs so it does not try to fire up.
Crank motor for about 10 seconds or so and watch the hose feeding your container.
Regular strong spurts = Fuel pump performing O.K.
Strong spurts to begin with tapering off as you go on = Fuel pump starting to fail.
Dribbles or weak spurts or nothing =- Failed fuel pump.

Good Luck and post back results.

 

[brew0688]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Easy fuel pump output test.
Remove the fuel pump to carb's hose at the pump.
Connect a temporary length of hose to the pump outlet.
Get a container to catch fuel.
Put muffs on if not in the water to save the impeller.
Pull lanyard or remove plugs so it does not try to fire up.
Crank motor for about 10 seconds or so and watch the hose feeding your container.
Regular strong spurts = Fuel pump performing O.K.
Strong spurts to begin with tapering off as you go on = Fuel pump starting to fail.
Dribbles or weak spurts or nothing =- Failed fuel pump.

Good Luck and post back results.

Good, Strong pulses of fuel. This fuel pump is brand, brand new, and definitely not the culprit. I can't explain my frustration at this point. Tomorrow I'm going through every single solitary test procedure in the manual, from electrical to fuel. If I don't find something, I'm biting the bullet and taking it to a marina.

 

[kenmyfam]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Glad you have verified the pump. I would be revisiting the carbs again and also verify that the pulse line is connected properly both ends and is in good condition.

 

[brew0688]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Easy fuel pump output test.
Remove the fuel pump to carb's hose at the pump.
Connect a temporary length of hose to the pump outlet.
Get a container to catch fuel.
Put muffs on if not in the water to save the impeller.
Pull lanyard or remove plugs so it does not try to fire up.
Crank motor for about 10 seconds or so and watch the hose feeding your container.
Regular strong spurts = Fuel pump performing O.K.
Strong spurts to begin with tapering off as you go on = Fuel pump starting to fail.
Dribbles or weak spurts or nothing =- Failed fuel pump.

Good Luck and post back results.

Are your float levels set correctly.
Spray some gas/oil mixture in the carbs and if engine starts, it has got to be a fuel delivery problem.

You say the motor dies with a BOOM. Is that just a figure of speech or is that a description of what it is doing? If it sneezes out and dies violently it sounds like it is dying lean (no getting fuel). Best of luck to you. From one college student to another!

Good, Strong pulses of fuel. This fuel pump is brand, brand new, and definitely not the culprit. I can't explain my frustration at this point. Tomorrow I'm going through every single solitary test procedure in the manual, from electrical to fuel. If I don't find something, I'm biting the bullet and taking it to a marina.

I just had a thought. Maybe this is the problem....

From everything I've gone through, I'm thinking that the issue is that the cylinders are somehow not creating enough of a vacuum to pull the fuel/air mixture into them.

When I replaced all the fuel lines, there was one line that I didn't know exactly what to do with. I couldn't remember quite where it had come from.

It's on the bottom portion of the block, and my dad thinks it to be a "cylinder drain" line. It connects the block to the airbox. It's below the pulse line from the block into the fuel pump. Any idea if this could be causing an issue? If it is leaking, or doesn't have a check valve on it, doesn't that allow an escape for vacuum that would otherwise be pulling air/fuel into the cylinders through the carbs?

 

[emdsapmgr]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Yes, your engine should have an airbox drain line which will connect to the hose barb under the bottom carb. It recirculates extra fuel/oil which may accumulate in the bottom of the airbox, esp if the engine is tilted up overnight. Your engine should idle at 650-750 rpm when in gear when floating at normal level in the lake. A low idle can cause the engine to idle poorly and shut off unexpectedly. Poor idle can also be attributed to dirt/dried fuel in the idle circuits of the upper carb bodies. When you cleaned the carbs, did you spray an aersosol carb cleaner through all the passages of the carbs? Compare the spray from one passage with the spray from the same passage on the other carb. The idle circuits are separate from the mid and high speed jets.

 

[cougar1985]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

here,s a from out in left field test.you say the motor only runs for 30 or so then dies with a shudder and sneeze?hers what happened to my 90 recently.over the last few trips i noticed my motor dying at idle quite frequently,would start right up again but die again after maybe a minute.everything seemed fine so i was sort of at a loss until i remembered something from years ago that i checked on my 90 also.here we go ,the female connection that attaches from the tank hose to the motor connected but didnt CLICK!sounds like everythings ok doesnt it?well unless you hear a audible click its not really seating properly and hence not functioning properly .it may stay on ,may seem ok but it is not !a couple of bucks later my 90 is back to its idle all day long self.if i hadnt remembered that problem from years gone by id still be chasing a ill running motor issue to no avail.its a stupid little thing but so critical to a good running motor.

 

[brew0688]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

Yes, your engine should have an airbox drain line which will connect to the hose barb under the bottom carb. It recirculates extra fuel/oil which may accumulate in the bottom of the airbox, esp if the engine is tilted up overnight. Your engine should idle at 650-750 rpm when in gear when floating at normal level in the lake. A low idle can cause the engine to idle poorly and shut off unexpectedly. Poor idle can also be attributed to dirt/dried fuel in the idle circuits of the upper carb bodies. When you cleaned the carbs, did you spray an aersosol carb cleaner through all the passages of the carbs? Compare the spray from one passage with the spray from the same passage on the other carb. The idle circuits are separate from the mid and high speed jets.

here,s a from out in left field test.you say the motor only runs for 30 or so then dies with a shudder and sneeze?hers what happened to my 90 recently.over the last few trips i noticed my motor dying at idle quite frequently,would start right up again but die again after maybe a minute.everything seemed fine so i was sort of at a loss until i remembered something from years ago that i checked on my 90 also.here we go ,the female connection that attaches from the tank hose to the motor connected but didnt CLICK!sounds like everythings ok doesnt it?well unless you hear a audible click its not really seating properly and hence not functioning properly .it may stay on ,may seem ok but it is not !a couple of bucks later my 90 is back to its idle all day long self.if i hadnt remembered that problem from years gone by id still be chasing a ill running motor issue to no avail.its a stupid little thing but so critical to a good running motor.

Thanks for the replies... Should that drain line have a check valve of some sort on it? Or should it freely allow passage both ways?

I've thought about the connection to the motor being a potential issue.... even to the point of my having bypassed it completely, just to test it. No change. :-/

I appreciate the continued support guys.

 

[Drum Luck]

Re: 85 Johnson 115 just won't idle. I've gone through EVERYTHING!

So does it die just at idle or does it die when your reving it too? Is it an exact amount of time 30 seconds or is it a diffrent amount of time each occurance? Did you punch out the two plugs that are in the bottow of each carb that cover the idle circuits. They don't look like they should come out but they do and when you get the rebuild kits they are the things that look like the size of a dime. If you didn't take them out then u may have all kinds of crap inside those and that would deffinily cause the problem your having. Just a thought.