Johnson 120 issues.

[Leglav8s10]

1994 Johnson 120 J120TLARK outboard on a 1991 Alumacraft Competitor 185cs.

Here's the problems:
1. Misfire from off-idle - 2500rpm or so
- Idles pretty good, and runs good on WOT. Slight studder when you go
- Idle timing is set to 8*ATDC (Clymer Shop Book)
WOT but cleans out pretty quickly and runs fine.
2. Smokes a LOT on a cold start, and moderate smoke each time you restart. (after sitting for awhile)
- Tends to smoke and load up after running through large no-wake zones
- Checked the Pulse limiter fitting - clean as a whistle.
3. Wet Plugs. I was given the wrong plugs (NGK BPR7HS)- auto parts house didnt give me the Inductive Resistor plugs that I needed (and kept running them for 2 seasons not knowing this). I then put BZ7HS-10's this spring (QL77JC4 equivalents - my buddies told me NGK was better for 2 strokes). Changed those out after 1 tank of gas for actual Champion QL78YC's. Plugs still wet (oil). Now I have QL82YC's in it. It idles pretty smooth, and the plugs aren't nearly as wet. (I leaned the idle mixture down about 1/4 turn each carb)
- I ran 1 can of seafoam in 3/4gallon of gas through the engine to remove the carbon. This took care of a lot of it, but I am going to run a can of OMC Engine Tuner in it next. Carbs were cleaned and rebuilt by the dealer when I bought the boat.
4. Oil Consumption. Oil tank was just above 1/4 tank and I added 1 gallon to it. It swallowed this gallon of oil on just about 30 gallons of gas, *maybe* 35 gallons max. I use Amsoil Synthetic HP Injector oil.
- Most of the shops I've talked to told me I should run it as is since its getting plenty of oil. I disagree since oil is $28-34 a gallon. I went on a week-long fishing trip last year and after 2 1/2 tanks of gas (full tank is about 25 gallons) I went through about 2 1/4 gallons of oil.
5. Gearcase was replaced a year ago (from the iboats store - OBR Remanufactured) and when going WOT, *occasionally* it seems like the gearcase is skipping a tooth and the boat lurches a little bit when it happens. It has only done this while on full WOT, never under WOT. I followed the break-in instructions to the "T" that came with it. Gear Lube was changed after break-in. Magnetic drain plugs had some really fine shavings on them, but not caked up and no chunks of any sort. The shift rod that came with the lower unit was about an inch too long, so I reused the old one and have it screwed in about 1/2 way. The shift controls are adjusted so it shifts into gear (both F & R) quickly and fast. No "ticking" noises while shifting.
6. When running over 2000rpm, Voltmeter reads 16 volts. At idle it reads between 12.5 and 13.5v
-----
Compression test (cold engine) yielded (1,2,3,4): 130,135,130,137psi. Port side cylinder bank (2 & 4) has a new head gasket, other side hasnt needed to be replaced yet.
Thermostats were replaced 2 years ago - I thought it was overheating but it wasn't. Water comes from the tell-tale indicator, but is only lukewarm (water temp on the Mississippi is about 60* here in MN) No water comes from the exhaust port on the back of the engine case (above waterline) ever.

Sorry for the long post.. I just wanted to get it all in here so I could get some good feedback. I would like my engine to run properly. IMO, it shouldn't smoke nearly as much as it does. It shouldn't misfire at all or very little. It should be using no more than 1 gallon of oil to 50 gallons of gas, and it shouldn't studder when going WOT. When I seafoamed it, the warmest I could get the cylinder heads up to was 96-99* depending on where you checked it. Is this engine just junk or do I have to revamp the whole fuel system and tweak a few other things? I can't afford to take it to a shop, so I need to be able to do this myself.

Thank you if you even just read this and don't reply.. I hope someone has some light to shed on the subject..

 

[mhg]

Re: Johnson 120 issues.

I'm don't know much about how the vro pump regulates the oil to gas ratio, but
you have way to much oil useage
This can be causing all your problems
it should be at 50:1
Take a 6 gal. tank and mix it at 50:1 and run this thru the system with the oil line disconnected
then you will need to find out why the pump is pulling to much oil
Also I would go to pennziol semi syn. oil
12.00 to 14.00 a gallon
you don't need that high dollar stuff
Mike

 

[marinemech1]

Re: Johnson 120 issues.

A fuel restriction or air leak will cause excessive oil useage.
you could put a clear piece of hose and a vacuum meter on fuel in side of motor watch for low vacuum and air bubbles - air leak or high vacuum and air bubbles - really vaporized fuel high vacuum anything above 4 usually antisiphon valve in tank.
Skipping at high speed could be rev limiter what does it rev at?? Power pack may have a number similar to 6200R= limits engine rpm to 6200
Check voltage at battery as many gauges are inaccurate. High voltage could be a poor or corroded connection.
Wayne

 

[marinemech1]

Re: Johnson 120 issues.

If you can't get. temps up remove thermostats probably stuck due to sand etc clean out and put back Motor should be around 140 degrees f at idle on both heads.
Wayne

 

[Leglav8s10]

Re: Johnson 120 issues.

I'm don't know much about how the vro pump regulates the oil to gas ratio, but
you have way to much oil useage
This can be causing all your problems
it should be at 50:1
Take a 6 gal. tank and mix it at 50:1 and run this thru the system with the oil line disconnected
then you will need to find out why the pump is pulling to much oil
Also I would go to pennziol semi syn. oil
12.00 to 14.00 a gallon
you don't need that high dollar stuff
Mike

The VRO is supposed to regulate fuel/oil mixture. The VRO pulls oil and fuel into the mixing chamber and sends mixed fuel to the carburetors. It is supposed to run 75:1 or so at idle/low speeds and 50:1 anything above like 1500rpm. I suspect the diaphragm is bad in the VRO pump - I am pretty much planning on replacing the VRO, however I am going to buy a vacuum pump to test the pump to rule it in or out.

I will not use any pennzoil product. I will only use Amsoil synthetic or Johnson/Evinrude. The Amsoil synthetic is cheaper than the Johnson mineral oil, thats why I've been using it. I changed from the standard Johnson oil - smoked too much.

 

[Leglav8s10]

Re: Johnson 120 issues.

A fuel restriction or air leak will cause excessive oil useage.
you could put a clear piece of hose and a vacuum meter on fuel in side of motor watch for low vacuum and air bubbles - air leak or high vacuum and air bubbles - really vaporized fuel high vacuum anything above 4 usually antisiphon valve in tank.
Skipping at high speed could be rev limiter what does it rev at?? Power pack may have a number similar to 6200R= limits engine rpm to 6200
Check voltage at battery as many gauges are inaccurate. High voltage could be a poor or corroded connection.
Wayne

All of the primer bulbs and fuel/oil hoses have been replaced, as well as the fuel filter. Fuel flows easily up to the pump and into the bowls. I used the crimp-style band clamps on all hose connections to the VRO pump, fuel tank, and oil tank. If there is an air leak, its gotta be tiny. I am going to get a vacuum pump/gauge to test the VRO (like I said in my previous post) but I am willing to bet its junk.

The skipping sounds mechanical. The engine is topping out at 5800rpm WOT in forward gear. It started doing this when the new lower unit went on and got broke in. (no WOT during break-in) I'm using a 13 7/8" x 19P SST prop.

 

[Leglav8s10]

Re: Johnson 120 issues.

If you can't get. temps up remove thermostats probably stuck due to sand etc clean out and put back Motor should be around 140 degrees f at idle on both heads.
Wayne

Even if the fresh water temp (from the lake or river) is is only 55-60*?

 

[marinemech1]

Re: Johnson 120 issues.

A small air leak or high fuel restriction will cause your symptoms clear line and vacuum gauge will show.
Yes engine temp should come up to over 120 degrees in even cold water as motor is thermostatically controlled. Actual specifcation 140+\- 15 degrees but I am happy above 115.
Vro pump may be scrap as you say but your only issue is using too much oil (pump is working too good) motor is not running out of fuel. I would trouble shoot fuel delivery.
Also if in doubt hook it up to 5 gal portable tanks and compare oil usage (don't run tanks dry same as air leak).Wayne

 

[Leglav8s10]

Re: Johnson 120 issues.

A small air leak or high fuel restriction will cause your symptoms clear line and vacuum gauge will show.
Yes engine temp should come up to over 120 degrees in even cold water as motor is thermostatically controlled. Actual specifcation 140+\- 15 degrees but I am happy above 115.
Vro pump may be scrap as you say but your only issue is using too much oil (pump is working too good) motor is not running out of fuel. I would trouble shoot fuel delivery.
Also if in doubt hook it up to 5 gal portable tanks and compare oil usage (don't run tanks dry same as air leak).Wayne

I just pulled the thermostat housings off and the rubber grommet that the t-stat fits behind has a small hole in each one. I don't remember these being present when I put the new t-stats in 2 years ago. I will pick up 2 new grommets later this week.

When hooking up a vacuum gauge to the fuel inlet side, does it matter where I put it in, and do I just use a "T" fitting to temporarily add it in? It would be easiest to put it right after the primer bulb on my boat.

If the vac. readings are low, and no air bubbles are present then I would assume the VRO is junk and needs to be replaced..?

 

[marinemech1]

Re: Johnson 120 issues.

Yes at the primer bulb will work.If vacuum low and no air bubbles move vacuum gauge to inlet of pump and retest.Also if you can hear it note the "clicks" the VRO is making should only click once every few seconds there is no spec but it shouldn't be "clicking" rapidly.
Wayne

 

[Leglav8s10]

Re: Johnson 120 issues.

Yes at the primer bulb will work.If vacuum low and no air bubbles move vacuum gauge to inlet of pump and retest.Also if you can hear it note the "clicks" the VRO is making should only click once every few seconds there is no spec but it shouldn't be "clicking" rapidly.
Wayne

I did notice the clicking on Saturday. When I was seafoaming the carbon away, I heard the VRO clicking. I'd say it was clicking every 3 or 4 seconds or so.. From what I was reading from another thread, if the number of clicks dont mesh with the programming in the electronics, it will trip the alarm and I hadnt had the alarm trip at all Saturday. Sunday the low-oil alarm (short tones every 20-30 seconds) kicked in when the oil tank got just below 1/4 full.

A few shops I've talked to don't recommend using the diaphragm repair kits and insist on replacing the whole pump as a whole. Do you or anyone else agree or disagree with this? (should it be a faulty VRO, that is..)

 

[marinemech1]

Re: Johnson 120 issues.

I've rebuilt a lot of them with no issuses, in the later service manuals there is a flow chart to test fuel side of pump...it works well...don't forget to check oil side after installation
But it still sounds like you have a fuel delivery problem to me.
Wayne

 

[marinemech1]

Re: Johnson 120 issues.

P.S. every time pump clicks it pumps a small amount of oil therefore the more clicks the more oil.Every time it pumps oil it resets the electronic no oil warning.
Wayne

 

[Leglav8s10]

Re: Johnson 120 issues.

I've rebuilt a lot of them with no issuses, in the later service manuals there is a flow chart to test fuel side of pump...it works well...don't forget to check oil side after installation
But it still sounds like you have a fuel delivery problem to me.
Wayne

Well, I will fix the t-stat grommets and pull the floor out and start from the tank up. I guess I'm having a hard time believing there is a fuel flow problem up to the pump as gas flows super easy through the filter up to the pump but only a vacuum/pressure test will prove or disprove this. I will get on this and post back what I find out. I havent been able to find the right part number for the VRO kit - iboats.com doesnt list a 120hp johnson in their fuel pump part number tables. 94 J120TLARK.

side question: whats the differences between the 120 and 140's? All I saw on the parts diagrams is the carbs are different. Could you swap the necessary 140 parts to a 120 and get the extra 20hp out of it?

 

[Leglav8s10]

Re: Johnson 120 issues.

I was looking at the VRO troubleshooting flow chart and it refers to a gearcase pressure tester and a gearcase vacuum tester to test the functionality of the VRO pump. Where the heck can I get something like this without having to order it and wait a week to get it?

 

[Leglav8s10]

Re: Johnson 120 issues.

Any ideas? I am really leaning towards just replacing the VRO pump. I think its the original pump and probably just needs to be replaced.

 

[marinemech1]

Re: Johnson 120 issues.

I think rebuid kits are listed at evinrude.com epc ob accessories
120\140 differencers are the carbs and intake manifold not really worth spending time\money on conversion in my opinion.
If you get creatve gearcase pressure tester could be a bike air pump etc. for vacuum you could buy a miety vac. pump from auto parts store etc.
Wayne

 

[Leglav8s10]

Re: Johnson 120 issues.

I think rebuid kits are listed at evinrude.com epc ob accessories
120\140 differencers are the carbs and intake manifold not really worth spending time\money on conversion in my opinion.
If you get creatve gearcase pressure tester could be a bike air pump etc. for vacuum you could buy a miety vac. pump from auto parts store etc.
Wayne

I'm gonna bite the bullet and just replace the pump. I don't want to mess around with it. I am almost positive its the original pump from 1994. I know they have been redesigned and work a lot better.

The 140 uses different reeds, intake manifold, and carb jets/orifices. The rest of the carb is the same. The only real bummer is the Reeds are 130$ a pop and ya need 4 of them. I'm gonna look locally and see what I can find.. $600 is a lot cheaper than $9,000 for a new engine..

 

[Leglav8s10]

Re: Johnson 120 issues.

I got a can of Johnson engine tuner, and I wanted to know if you really have to take the prop off. The instructions say to remove prop before putting the stuff in.. is it really needed, and why?

 

[Leglav8s10]

Re: Johnson 120 issues.

Okay.. I ordered a new VRO/OMS pump. that should cure the main issues with this engine. One question was never really answered: Occasionally (once or twice per outing, maybe.) the engine (at WOT only) will seem to skip.. like its momentarily popping out of gear. When it "skips", it sounds/feels like hitting a log at speed. It never did this before I replaced the gearcase. (Reman'd from iboats.com store - OBR rebuild) I used the shift rod that was in the motor, not the one they sent with the gearcase(wrong length). I haven't removed the gearcase yet, however I am concerned as the warranty is either up or will be up soon. Gearcase Oil was changed after 10hrs of break-in time and was still blue. Minimal metal specs in oil. Refilled oil, double checked level this spring - full and drain plugs are clean. Whats going on here? I set the shift rod height to the spec in my book, 21 15/16". Shifting is good - very quick, solid shift both F and R.....