Posted: 4/29/2024 2:26:06 AM EDT
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I was wondering if anyone had any experience with the oil injection systems on this vintage outboards? This particular outboard runs great and I, nor my father in law, have had any issues with the oiling on it. I know certain outboards its known that you're better off to just mix and not rely on the oil injection systems. I have no idea about Yamaha though. This is my first one. I know it has an oil tank on board, is it alright to use this or should I disable/remove and just mix the oil/gas? Any input is appreciated. This is on a 1984 Alumacraft 17 MV Bandit hull. Given to me by my father in law. Just a little boat to take the boys out fishing once in a while. |
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Yammie oil injection is/was pretty damn good. Keep the oil tank and filters clean. Use a good oil. (Still new pumps available on internet.) Still some of the older ones running around up here in Alaska with very little maintenance done to them. |
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Appreciate the replies, fellas. I'm seeing quite a few people on the internet saying the Yamaha oil injection systems are pretty solid. Always makes me nervous though...relying on a system like this to oil the engine. I haven't made a decision yet....hoping for more input. |
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Like mentioned above, keep the oil tank, lines and filter clean and it will do just fine. The oiling systems that were problematic were the Johnson/Evinrude VRO systems, Mercury "Auto Blend" and the early gear driven Mikuni pumps. It wasn't the Mikuni pump that was the issue, it was the soft plastic drive gear mounted on the crank that would get shredded. the Yamaha probably has a Mikuni pump, but I haven't heard of any issues with the Yamaha system. Does it have an electronic "black box" for the oiling system? I'm not a Yamaha guy but recall that some had a main oil tank in the hull and a small tank on the engine. The oil tank on the engine being fed with an electric pump? @akethan will know and most likely correct me. 
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...behind every blade of grass...
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No in hull tank on this one. Only the tank on the outboard as far as I know. I haven't been able to inspect the outboard to a great degree yet. But I do know that there's no tank on the boat itself, I confirmed that with the guy that installed the outboard. This was a repower from a Mercury 50hp outboard that had a ton of hours and was needing repairs...as cheaper to repower with this Yami. I have no reason to believe the tank/lines are dirty so I'll probably just keep on running it. Appreciate the help. |
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Originally Posted By KB7DX: Like mentioned above, keep the oil tank, lines and filter clean and it will do just fine. The oiling systems that were problematic were the Johnson/Evinrude VRO systems, Mercury "Auto Blend" and the early gear driven Mikuni pumps. It wasn't the Mikuni pump that was the issue, it was the soft plastic drive gear mounted on the crank that would get shredded. the Yamaha probably has a Mikuni pump, but I haven't heard of any issues with the Yamaha system. Does it have an electronic "black box" for the oiling system? I'm not a Yamaha guy but recall that some had a main oil tank in the hull and a small tank on the engine. The oil tank on the engine being fed with an electric pump? @akethan will know and most likely correct me. Never had a problem as I was religious on clean oil and filter changes every year. |
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Originally Posted By eclark53520: I'll have to figure out the filter situation and maybe get that changed. I have no idea if it's been changed. What do you guys suggest for good oil? I might drain the system and refill with something known. I don't know what's in it now. Might not be in stock anymore. I ran bulk mercury oil in my yammie 150,40hp Johnson,merc 40hp and suzuki 140/85hp. No problems with it. |
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Mercury/Quicksilver Premium 2-stroke is GTG. When we had Merc 2-strokes in our rental fleet we never had an oil related failure. Those motors had more than 2000 hours on them and were beaten like a rented mule. Yamalube is GTG also obviously. If you use another brand, make sure it is TCW-3 rated, no "chainsaw" or other 2-stroke oil designed for air cooled engines. |
...behind every blade of grass...
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Figured I would just ask my new question in this thread: My problem now is that this engine is leaking oil like crazy through the carbs. Sitting in the driveway, the oil in the tank is leaking out through the carbs, filling up the spark arrestor/air box running down into the case and running out where the cables go in. It also smokes like crazy when I start it after it's been sitting for a while...obviously because it's got a bunch of excess oil in the carbs/engine. My Any suggestions? I see that there's a check valve in each line running to the carbs, however, those valves are going to allow pressurized oil from the tank to flow to the carbs right? It's a one way check valve, so oil to the carbs goes, oil back from the carbs is stopped? Should I vent the tank somehow when it's sitting? Is there a tank pressure vent that might be clogged...I don't see one on the parts diagram? I'm spending more time cleaning up oil off the engine than actually running this thing. Any advice will be helpful. |
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The gas will evaporate and leave the oil. You should mark the oil tank with a Sharpie to note the level. Then compare it after the boat sits a while (days) and see if it is in fact leaking oil only. My guess is that the sealed fuel tank is building pressure and forcing fuel/oil mix past the needle and seats in the carbs which in turn spills out the front of the carbs and into the air box and into the cylinder block. This makes for a smokey start up. If it ends up being oil only, then the oil tank is probably building pressure and forcing oil past the check valves and into the carb, air box and into the block. Could have dirty or defective check valves not sealing and keeping the oil out of the carbs when not running. |
...behind every blade of grass...
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So I don't think that's an issue mainly because (as far as I know) the fuel and oil do not mix in this system until it's pulled into the engine itself by the intake pulses. The oil lines are connected to a plate that is mounted between the intake reeds and the carbs. The fuel in the bowl is pure gasoline. So even if the fuel was spilling out, I don't believe it would contain any oil. At least, from looking at it and seeing the drawings, I don't know how it could be. I can look again, but that's how it seems to be working. Each cylinder has it's own dropper of oil on the top of each intake. Where as the fuel is supplied from the bottom coming up through the bowls as a normal carb function. |
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I think the check valves might be a problem, but I think it could also be the pump. Sounds like if the pump actuator system isn't adjusted properly it can keep the pump in state to allow the oil to flow through the lines. There isn't a ton of information out there about it but I did a bunch of searching last night and those seem to be the solutions. The main solution I see is to just delete the oil injection system. |
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Here's behind the oil tank. Pure gasoline in the bowls, oil is dripped in to each intake throat individually. I did adjust the oil pump 2 turns to close it more fully at idle. Doesn't seem to have changed where it is at WOT though because of how it rotates as it opens. Hopefully that's not too much, but I can't seem to find specs anywhere on how it should be adjusted. |
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Hmm. It's strange that the oil would be pushed "uphill" from the pump to the plate behind the carbs. You may be able to remove and clean the check valves with some carb cleaner sprayed through them. It may help, it may not. IMO, I'd try to fix the oil injection system before eliminating it. |
...behind every blade of grass...
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Yeah, it's an interesting system. I'm not interested in eliminating it at this point. I think I will remove and clean the check valves. The only reason I didn't last night is because I don't yet have a way to run the engine on mix while I bleed the air out of the system afterwards. Appreciate your thoughts on the issue. It's not a massive problem, but it's annoying when the back of my boat has oil dripped in it all the time and I have to keep cleaning it out. Seems like if I keep the outboard off of the transom saver and tilted back it doesn't leak out so bad though. So I might just store it like that. Should solve most of the issues assuming the check valve cleaning doesn't fix it completely. |
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No. When I got the boat the area right in front of the outboard was filthy with oil. I didn't really know why, I figured it just got spilled and never cleaned up or it leaked from the oil tank. I cleaned that and what I could get to inside the engine area. Once I had it for a while and started poking around trying to find the leak I realized it was coming out of the carbs. It's been like this for at least 2 years. |
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It's common for 2 stroke engines to leak gas out of the carbs when tilted up. Usually the air box contains the mess, but sometimes not. Tilting the engine when stored can make it worse because the float(s) needle and seats in the carb(s) is more easily defeated and pressure build up in the fuel tank can over-ride the needle and seats making the carb(s) dribble fuel out of the carb throats. The oil is puzzling though. Most 2-strokes mix the oil just before the carb inlets or in the fuel pump. I could see the check valves leaking and pressure build up in the oil tank forcing oil past the check valves and out the carb throats when the engine is tilted up during storage. Maybe store the engine trimmed down (vertical) and loosen the oil tank cap so it won't build any pressure and see if it helps. Just remember to tighten the oil cap back up before use. |
...behind every blade of grass...
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Originally Posted By eclark53520: Here's behind the oil tank. Pure gasoline in the bowls, oil is dripped in to each intake throat individually. I did adjust the oil pump 2 turns to close it more fully at idle. Doesn't seem to have changed where it is at WOT though because of how it rotates as it opens. Hopefully that's not too much, but I can't seem to find specs anywhere on how it should be adjusted. They do get brittle and crack. If they do not pinch easy replace them. |
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Originally Posted By KB7DX: It's common for 2 stroke engines to leak gas out of the carbs when tilted up. Usually the air box contains the mess, but sometimes not. Tilting the engine when stored can make it worse because the float(s) needle and seats in the carb(s) is more easily defeated and pressure build up in the fuel tank can over-ride the needle and seats making the carb(s) dribble fuel out of the carb throats. The oil is puzzling though. Most 2-strokes mix the oil just before the carb inlets or in the fuel pump. I could see the check valves leaking and pressure build up in the oil tank forcing oil past the check valves and out the carb throats when the engine is tilted up during storage. Maybe store the engine trimmed down (vertical) and loosen the oil tank cap so it won't build any pressure and see if it helps. Just remember to tighten the oil cap back up before use. Appreciate it! I took it out again tonight and it didn't smoke nearly as bad as it usually does. Of course, it's only been 4 days since last time I took it out...so I'm guessing I cleared out most of the excess oil last time and it hasn't had enough time to build up again. I thought maybe the pump was being held open, however, after thinking about it, even at idle the pump needs to be pushing oil out...so, it's going to be open to some degree at idle. I think I'll put the adjustment back to where it was and get the check valves cleaned up. Thanks again, KB. |
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Originally Posted By akcaribouhunter: Check the clear oil lines. They do get brittle and crack. If they do not pinch easy replace them. I like this idea. I'm going to be taking them off to clean those check valves anyway, so I'll just replace them. Then I know they're good. |