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1995 Johnson 50 HP stalling out/hard starting, high speed fine
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| joz |
Posted on 08/29/15 - 8:48 AM
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My 1995 Johnson 50 HP motor just had a slight overhaul. The oil pump was failing so I had it converted to fuel/oil mix. during the conversion the tech noticed that I didn't have spark to one of the three cylinders, so he replaced power pack and cleaned all terminals to other cylinders. Motor was still running rough so he drained all carburetors. He said they were filled with oil from the failing oil pump. I took the boat back and it ran well and smoked less than it has since I've owned it. The following weekend I took it out, and it was very hard starting. Once I got it running, I throttled down a little, and it smoothed out. I ran 3/4 throttle, then full, then backed off, and it seemed to run well. Then I had to slow up in a no wake zone, and at idle speed it died. Then it was hard to start again. Once started, I got back to the ramp with no trouble and figured it was ok.
That was last week. This morning, I launched the boat, and it started quite easily. I advanced the throttle to warm it up a bit, then when I backed off to idle, it died again. It will start right up, idle to about 1000, then drop suddenly to 500 rpm and die. I got it started and throtted down, and was able to get it to start moving, albeit very rough. Then, all of a sudden it would kick in and start to speed up and smooth out. It runs flawless at above 1500 rpm, and the biggest issue seems to be start up and at idle. Plugs look good, compression seems fine (without numbers), and fuel is fresh and treated with seafoam. Could the carbs need to be cleaned do to the over-oiling while the pump was going? Any ideas would be great.
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| wlagarde |
Posted on 08/29/15 - 12:55 PM
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Jaz -
It does sound like a fuel problem. Have you tried pumping the fuel bulb while underway and if so does that make the problem disappear? If it does then it suggests a fuel pump problem.
I would first check the compression on all cylinders. You can purchase an inexpensive compression tester on Amazon. Also, purchase a service manual as it will provide you with critical details needed to self service your engine.
Next remove the carbs, disassemble them, clean with carburetor cleaner, and then ultrasonically clean them. Reassemble them using a carburetor rebuild kit. I would also do the same for the fuel pump.
While you have the carbs off remove the intake manifold and inspect the reed valves to make sure there is not a problem there. Here is a link that will give you an idea of what to expect: http://www.whalercentral.com/userphot...lbum_id=65
1976 Sport 15 w/ 2005 50hp Nissan 2 stroke |
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| tedious |
Posted on 08/29/15 - 2:26 PM
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Joz, do you know what the mechanic did to convert to premix? Did he actually replace the fuel pump?
Also, do you notice a change in the color or volume of smoke when the motor is dying at low RPM?
I am thinking about a failed diaphragm in the fuel pump pushing fuel back into the crankcase, over fueling it at low RPM. Obviously if the mechanic replaced the fuel pump that is less likely.
Edited by tedious on 08/29/15 - 5:19 PM |
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| joz |
Posted on 08/30/15 - 4:25 AM
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The mechanic did not replace the fuel/oil pump. He said just the oil pump side had gone and fuel pump was fine. ThTs why I had it converted rather than replacing the pump which was $600. That seemed to make sense since it ran fine two weeks ago after I got it back.
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| tedious |
Posted on 08/31/15 - 6:43 AM
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Joz, it sounds like your motor only ran right that one time when you got it back from the mechanic, correct? And then the next time out it was hard to start and rough at low RPM? What happened in between - did you have the cowl off and / or make any changes?
If it is running OK at speed then chances are the carbs are OK - any excess oil should long since have been dissolved. Have you checked to make sure the priming lever (red lever on the side of the primer solenoid) is not set to the prime position?
Can you clarify the smoke situation when the rough running is occurring? I am still thinking overfueling, from either the primer valve or a leaking fuel pump diaphragm; either would result in additional smoke. If you are going to stick with premixing fuel you can replace the expensive VRO pump with the non-VRO version and the price is much less - around $70 when I did it 5 years ago.
Tim
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| wlagarde |
Posted on 08/31/15 - 10:41 AM
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tedious wrote:
If it is running OK at speed then chances are the carbs are OK
Tim
Not necessarrily. If there is debris in the idle jet but not the main jet the engine will idle poorly but run fine as one opens up the throttle.
1976 Sport 15 w/ 2005 50hp Nissan 2 stroke |
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| joz |
Posted on 08/31/15 - 2:09 PM
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Nothing happened in between trailering home from the lake after getting it back from the tech. I brought it out the next time, it started rough but then Smoothed right away. I idled up and down the river, throttled down all seemed great. On the way home that day it stalled while going at idle speed, didn't start right back up, but when I got going I just headed home. This last time, as I mentioned, it started rough, stalled out quickly, was eventually able to get it in gear with the throttle quickly put down, but the whole boat was shaking. Then all of a sudden it kicked in a took off. Went up and down the river high speed, good throttle response throughout range, then died at idle speed when I slowed to fish. Hard starting again, let it sit. Got it going and in gear, same thing. Got it back to to do I and left it at idle, idled for a minute or two then it died out. Put it on the muffs yesterday after draining the carbs and wiping what I could down. There was residual oil in the carb air openings right in front, and the plastic air of has some oil on it. Started it up, idled ok at 1000 rpm, then suddenly dropped to 500 rpm and stalled. Started again easily, idled ok at 1000rpm, and even settled to 750 ish rpms and I killed it. I saw the non-vro version of the pump on eBay for over $300. Could it be a bad cylinder? That would stink. Can you talk me out of that likelihood (please)! Don't really have the money for a repower or the know-how for a rebuild.
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| joz |
Posted on 08/31/15 - 2:12 PM
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Smoking seems consistent at all rpms. Not very much, no color change.
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| tedious |
Posted on 08/31/15 - 2:39 PM
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Everything you note is consistent with overfueling - which does not mean it is the problem for sure.
If you have confidence in the mechanic you took it to, take it back and let him have another go.
The non-VRO fuel pump you want, as far as I can tell, is OMC part 438557, priced at $107.80 here: http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1995&hp=50&model=J50BEEOD&manufacturer=Johnson§ion=Fuel+Pump+And+Filter
When I switched over, I had to figure out a way to mount the pump, but it's smaller than the VRO version so it was pretty easy. Your call whether to try it vs. take it to a mechanic - but 20 years later, your original fuel pump is likely on borrowed time anyway.
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| joz |
Posted on 09/07/15 - 9:31 AM
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UPDATE- Took the boat out this morning. I drained the carbs last weekend. Nothing extraordinary. Anyway, the motor started right up and ran nicely, idling Around 750-1000 rpms. Then, after about two or so minutes, rpm dropped to 500 then the Engine died. When I pumped the ball, it was completely empty. Pumped until firm, started right up, and idled great. I noticed that the bulb was emptying, so I pumped it every 15 or so seconds. I was able to keep the engine running smooth as silk so long as I pumped the ball. Above around 1500 rpm, I didn't have to pump the bulb at all and the engine ran great. Plenty of power and throttle response. At idle speed,I needed to pump the bulb when it started to sputter. Could it be a tired fuel pump?
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| wlagarde |
Posted on 09/07/15 - 9:38 AM
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Yes - Remove the fuel pump and clean it. Then install fuel pump rebuild kit. I would also recommend cleaning the carbs and installing carb rebuild kits.
Can you tell us the model number of your engine? You should be able to source a rebuild kit through boats.net: http://www.boats.net/parts/search/BRP...parts.html
Edited by wlagarde on 09/07/15 - 12:14 PM
1976 Sport 15 w/ 2005 50hp Nissan 2 stroke |
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| tedious |
Posted on 09/09/15 - 4:53 AM
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Joz, I originally responded to your other thread, so repeating what I wrote here:
Your experiment was great - it did definitely point to a problem pumping fuel. But before you replace the fuel pump, check the vacuum line running from the pump to the crankcase - if this is soft, or leaking even slightly, it will rob the pump of power. It's just a piece of 1/4" fuel line, so you might even want to replace it and repeat your experiment.
That said, your problem is most likely the pump itself - I don't know if they still sell rebuild kits for the VRO pump, but that would be the way to go if they do, and if you want to go back to a separate oil tank. You could of course also replace the pump - the VRO pump is big bucks, but if you're OK with pre-mixing, you can get a non-VRO pump, as mentioned above, for a lot less.
Tim
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| jgortva |
Posted on 09/09/15 - 6:05 AM
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Joz,
I have a 95 Johnson 70H.P that has had the VRO pump disconnected. They were notorious for failing and scoring cylynder walls on the motors as the engine alarms either never went off or went off too late. Any Johnson Dealer will be familiar with this problem and will put in a standard mechanical fuel pump with no oil pump for about $250.00 including the bracket which must be fabricated. The first issue you might have would be if you had any cylynder damage when the pump was failing. Time for a compression test and even to have the cylunders scoped as a, "squashed" piston that will have eratic timing symptoms may not be low on compression. If the cylynders check out, the second issue is the design of the VRO system itself. The VRO is a variable oil injection system that pumps oil in at idle to 20:1 and then adjusts as high as 50:1 at high rpm. That is one reason a converted VRO engine will always run smotther at high rpm's rather than idling around. It is running too rich at idle but you cant lean out the 50:1 mixture or you willoil starve at speed. You can replace the VRO pump with a new one as the rebuilds and rebuild kits are also notorious for failing, or have the motor retuned by a good outboard mechanic to minimize the bad effects at idle and just live with it.
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| MarkTemplar |
Posted on 09/09/15 - 8:42 AM
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low idle adjustment??? maybe needs to be richer? Just a thought since I had same problem of building up speed after a carb rebuild. Mechanic adjustment was OK for the shop, but not for the open water.
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| joz |
Posted on 09/20/15 - 3:44 PM
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UPDATE- Replaced the VRO yesterday with a used one. Left the oil side un-hooked, and kept it a mix. Ran today perfect, idled all day, and got the acceleration back. Had a great day on the water. Thanks to all who chimed in and helped me solve this. I'm glad to have my engine back!
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| tedious |
Posted on 09/22/15 - 6:38 AM
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Nice work - your experiment with the bulb was key!
You could even hook up the VRO again if it was working for you - although it gets blamed for a bunch of other problems, it's a very reliable system.
Tim
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| WE Whaler |
Posted on 09/23/15 - 8:47 AM
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Thinking through this string of messages, one thing I see that wasn't discussed was looking at the fuel and vacuum lines on the motor. Having old outboards, I've had more than one occasion when I thought a similar issue was a fuel pump only to find that one (or more) of the fuel hoses on the motor had deteriorated. JOZ, it might be worth a few minutes to pull the cover off the engine and just check the hoses there on the motor to make sure they are all good and have no cracks.
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| mtown |
Posted on 09/23/15 - 1:14 PM
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What I like about Whaler Central.
Thanks Joe for providing it.
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