# Need help diagnosing issues with Johnson 150



## super_dork (Aug 25, 2015)

I just bought a 1993 Stratos 280 SF with a 150 Johnson V6 Silver Star Series outboard (Model VJ150ELATG). The previous owner just had it in the shop and had fuel pump replaced with one that uses the fuel/oil mix instead of the separate fuel and oil model. He also replaced some O rings. Not sure what else he did - it was about $900 in service. He mentioned that the mechanic initially told him that he would need to get the carbs cleaned since it was idling poorly. After the service, he cranked it and said it didn't seem to be idling poorly anymore.

So I've taken it out twice and here's what I'm seeing.

1) It takes a while to crank. I will prime and choke and it just takes quite a while to get it to even attempt to turn over.

2) after idling for a bit, then accelerating, it would die. It takes several attempts to get it to engage without stalling.

3) at high full throttle, the motor misfires? or something and the motor kicks up due to the boat speed and lack of thrust holding the motor down. The motor doesn't die, just stops for a split second then keeps running at top speed.

4) The water from the water pump isn't coming out in a stead stream, It's more like a spray. Not sure if that's normal or not.

5) After running then sitting with the motor off, it takes a while to get it to crank again. Killing for a short time doesn't have this problem.

I read that it could be water in the fuel - I pumped out about 5 gallons of the ~15 left in the tank and didn't see any water. Based on what I read, didn't seem like water was the issue, but I could be wrong.

I also read that it could either be the carbs need cleaning, the water pump needs work and/or the spark plugs need to be replaced. Just looking for some advice on what could potentially be the problem and what I can do to test/fix it. I am handy, just haven't really worked on outboards before, but certainly not afraid to try.

Thanks in advance!


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## Captain Ahab (Aug 25, 2015)

Star with the easy stuff-replace those plugs (check teh wires as well - look for burn spots and cracks - if found replace 

Then try just pulling off and cleaning the bowl of the carb - might have some debris or gum in there - spray it out with carb cleaner.

You can also try "de-carboning" using Sea foam - follow the directions on the can (may or may not help much but should not hurt anyway). 


Also, check your fuel lines to make sure the fitting are tight - the high speed "sputter" sounds like a slight fuel line vacuum leak


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## kofkorn (Aug 25, 2015)

Make sure you replace the water pump before you run the motor any longer. Should be a solid stream out of the tell tale. Spray can indicate a poor pump or possible blockages in the cooling system.


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## super_dork (Aug 25, 2015)

Thanks guys! I've never worked on an outboard before but I was able to download the OMC service manual for the motor, so I should have good info on how to do all of the repairs. It doesn't seem like it's gonna be that hard to do, just gonna take me time to feel comfortable that I'm not gonna destroy something. I'm going to hook it up to the hose and run it to verify that the water isn't coming out correctly. I was on the water at the time just kinda noticed it in passing, but didn't really stop to verify.

With the cover off, the motor looks very clean and nice - no corrosion or cracked hoses and such. Looks like it's been well maintained and serviced. Hopefully some carb rebuild kits and water pump rebuild kit will take care of things. Thanks again for the replies!


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## super_dork (Aug 28, 2015)

So I took the family out tonight. It didn't go so well. We got the motor running right away. I trimmed it down as far as it could go, which really helped with planning out, though the boat seamed to be leaning to the left while in motion, so I'm not sure what that's all about. Anyway, we ran at about half throttle, maybe 20mph or less for just a few hundred yards when the motor just quit. I was able to get it started again then it stopped again. Needless to say, after trying for a while to get it running, we just used the trolling motor to get back to the dock. At the dock, after it sat a while, I was able to get it running in neutral while working the throttle up and down. If I stopped working it, the engine would just cut out again and was hard to get started again. I'm guessing my next step will be checking the plugs and cleaning the carbs.

Also, I checked and the water is coming out if the pee hole, so I think the water pump is just fine.


So, seafoam or pull the carbs?


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## Nubbins (Aug 30, 2015)

So after it died was the priming bulb still pumped up or soft. If soft you could have a fuel pump problem or sucking air in the fuel system. Did you clean the carbs or drain them? You can eliminate the pump by manually pumping the bulb while operating the engine. But you'll be tired after running it like that. :LOL2:


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## Pappy (Aug 30, 2015)

First off....on the primer bulb.....it is supposed to be soft once the engine is running. The engine driven fuel pump is SUCKING fuel from the fuel line, primer bulb, and tank, not pressurizing it. This is a perfect example of folks giving information as fact on the internet when it could not be further from fact. 

As far as your boat leaning a little left, for a Bass boat that is pretty normal. They respond to engine/propeller torque and load placement a little more than shallow V hulls do. Once "on the pad" they straighten out and fly right so to speak. Once you get the engine issues straightened out and get up to WOT you may also experience a bit of chine walk until you learn to drive through it. Again, normal. 
Now, as far as the engine goes. No, Seafoam will not cure much of anything. Neither will the carbs as all carbs would have to be experiencing a simultaneous failure in order to shut the engine off suddenly. You have three fully separate metering circuits in each of those carburetors. 
Once you do a bit of reading around here you would think that installing of a set of NGK spark plugs and and adding dose of Seafoam to an engine would give you a brand new engine and breakfast in bed. Not so. 
If the shut-off is like someone turning off the key switch then most likely the failure is an ignition related failure. If you are mechanically inclined we can troubleshoot this, if not than an authorized dealer will be your best bet, not a lower priced shade-tree who will replace parts until he finally fixes....all the while feeding you a myriad of BS about what he thinks the problems are. Very often they will cost you more than going to an authorized dealer. Also the parts from an authorized dealer will carry a full one year parts warranty if they are OEM parts. If you decide to go to anyone other than an authorized dealer ask to see the manuals for your engine and a peak reading volt meter. If he cannot produce the latter....run. 
On your failure to accelerate. This particular engine is fairly succeptible to a phenomenon called "Heat-Soak" which is something that happens inside your carbs (in the Summer months) during a shut-down period of approx. 20-30 minutes give or take. Look it up if interested or I will explain further. The only cure for this is to richen the mixture on all 6 carbs, assuming all else has been checked and verified. We go as far as 6 turns if needed on the adjustment screws. 
On your starting issue. You mentioned priming and choking. You do not have both. You have a primer. 
A primer only works when the fuel system is pressurized, either from the primer bulb (pumping by hand) or the engine driven fuel pump. While cranking, the fuel system should have already been fully pressurized. Hold the key switch IN and engage the starter. Keep the key switch pressed in until the engine fires up. Simple. 
You may need to tickle the primer a few times until the engine warms sufficiently. 
The best angle of trim to start a cold or hot engine is level to trimmed down, never trimmed up or tilted.


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## Captain Ahab (Sep 2, 2015)

Good stuff as always Pappy and spot on too!~



I was not trying imply that new plugs and sea foam would fix any major problems - Only that the plugs are a quick and easy thing to do so he might want to start there


As i stated - Sea Foam probably will not help all that much but it does not hurt - I am not a huge fan by any means but again, it is cheap and easy to try


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## Pappy (Sep 2, 2015)

Not pickin' on ya. 

Sea Foam or any other fuel system cleaner will basically only work on a gummed up carburetor if the "gummed up" circuit is still partially flowing fuel through it. 
If the passageway or circuit is plugged then none of the cleaners that are mixed with fuel are strong enough and the carb must be disassembled and the circuits identified and cleaned manually or with a dedicated stand-alone carb cleaner. 
Spark plugs are quick and easy. Expensive when you have to purchase six of them though!


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## super_dork (Sep 8, 2015)

So, I ended up rebuilding all the carbs with OMC kits and replacing the plugs it cranked right up in the driveway on muffs. Several of the high speed orifices were pretty gunked up but everything else looked pretty decent.

Saturday, I took it out on the lake for testing. It cranked up fine at the launch but then I struggled to get it started back up after that. We tried for a few mins then it finally started. Didn't have any issues after that point. 

We rode at at about half throttle for a few mins then opened it up to WOT. After opening it up for a few min at WOT (~45mph) it cut out, just like I had been experiencing. The motor just stopped. No sputter, no idle, just dead stopped. After that, it would cut out at any decent speed, like half throttle or higher. It would crank right back up without issue. We fished on the trolling motor for about 30-45 mins and then started back to the dock. It cranked right up and we kept it at about half throttle at 20mph and it didn't cut out again (the trip back was maybe 10 mins).

So, I've heard that it could be starving for fuel at the high RPM and that I should try to push the key in to choke it and see if it kicks back to life. the OMC manual suggests that it may be electrical related and suggests doing voltage tests on the power pack. Any thoughts?


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## Pappy (Sep 9, 2015)

*Re-read my post above*. Yes, you are on the right track. 
Chances are you will need to replace both the power pack and the electronic eye. They should be replaced as a pair. Take your chances on replacing a pack only. If the eye is faulty it will take out the new power pack as well. 
In order to test you will need to catch the fault as it happens with a meter.....not easy to do while up on plane on a Bass boat. 
While the pack is not exhibiting the issue all readings on a CD-77 or Mercotronic meter will be absolutely normal. Your choice. 
Check all power pack grounds and connections. Pull the plastic shrouding and disconnect and see if anything is loose or corroded.


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## super_dork (Sep 9, 2015)

Pappy said:


> *Re-read my post above*. Yes, you are on the right track.
> Chances are you will need to replace both the power pack and the electronic eye. They should be replaced as a pair. Take your chances on replacing a pack only. If the eye is faulty it will take out the new power pack as well.
> In order to test you will need to catch the fault as it happens with a meter.....not easy to do while up on plane on a Bass boat.
> While the pack is not exhibiting the issue all readings on a CD-77 or Mercotronic meter will be absolutely normal. Your choice.
> Check all power pack grounds and connections. Pull the plastic shrouding and disconnect and see if anything is loose or corroded.



Hahah. I've read through it several times. It's quite the plethora of information. Thank you for taking the time to write it up.

I'm not crazy about trying to diagnose the powerpack since, as you said, it's going to be hard to catch the fault most likely.


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## super_dork (Sep 9, 2015)

So, I'm actually stuck. Which part is the optical eye?

https://www.boats.net/parts/search/BRP/JOHNSON/1993/VJ150ELATG/IGNITION%20SYSTEM/parts.html


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## Pappy (Sep 9, 2015)

Although it would have made WAYYY too much sense to put that piece in the ignitin section you will find it over in the throttle linkage section listed as #24!


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## super_dork (Sep 9, 2015)

Pappy said:


> Although it would have made WAYYY too much sense to put that piece in the ignitin section you will find it over in the throttle linkage section listed as #24!



After much anguish, I ended up there and found it after watching several videos showing how to replace it. Once I knew what it looked like, I just had to find it. It's even listed under ignition in the manual. Oh well. What's another $300 dumped into this machine? Maybe it will run well and won't ever give me any more issues! *fingers crossed*


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## super_dork (Mar 31, 2016)

Someone sent me a message and asked for an update on the motor.

After replacing the power pack and the optical eye, the motor runs perfectly! Thanks to everyone for all the help. 

Since fixing the motor, I proceeded to remove it from the boat and begin rebuilding the transom - it's been ~5 months since I started and I should be hanging the motor any day now. Since it's not a tin boat, I didn't post a build thread on here. If you are interested in seeing the project, you can check it out over here: https://www.bbcboards.net/showthread.php?t=652171 (hope it's not an issue linking to another forum). It's been quite a learning experience since I'd never done fiberglass before.

Anyway, I'm hoping to get the motor back on and fired up to see if it still runs!


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