I bought a boat with a 1990 Yamaha 2-stroke, it has been sitting for about a year. Just hooked up the battery and cleaned out the fuel tank. It started right up on 50:1 mix. The Yamaha manual says I should see oil moving in the hose after no more than 10 minutes at idle. The hoses are all dark colored, maybe discolored from oil, so I can’t see any oil moving through. How can I tell if the oil injection is working? Until I know for sure I plan on running mix, but I prefer not to do that indefinitely.
Chris V might be able to confirm this if I remember it from the Yamaha manual, start the motor, rotate oil pump link rod to WOT setting and while running at 1,500 rpm on 50:1, pop off one of the hoses at a connection after the pump and like you said it should have a steady drip also, depending on the hp you can measure how much it drips to ensure it is working correctly.
“Lil Mudslinger” - Lowe 160 W/50hp Yammie
I’ve got a '91 90 yammie. I filled the oil reservoir then ran it on a full tank of mixed gas for a few trips. Measured how much gas and oil it took to top off both tanks and did the math. Found that the oil injection system was only putting in100 to 1 ratio so I also run 100 to 1 in my tank now to get the proper 50 to 1. Works for me
Thanks for the advice. I’ll try the pop the hose off method first - if that looks good I’ll make a couple measurements and see where it’s running for mixture. In the mean time it looks like an impeller replacement is the next item on the list. Got her launched Saturday AM, tied up at the dock, went to get the kids from the parking lot and when I got back she was overheating, no water flow. Guess the first shakedown cruise was pretty short.
From the service manual:
OIL INJECTION PUMP
OPERATIONAL TEST
- Start the engine and set the idling
speed at 1,500 rpm by adjusting the
throttle-stop lever.
CAUTION:
Use only oil-mixed fuel (50:1) as malfunction
or engine seizure may otherwise
result. - Remove the oil-pump link-rod and fix
the oil-pump lever in the full-throttle
position. - Measure the oil discharge from each
port for three minutes using a measuring
cylinder graduated in steps of at
least 0.1 cc to confirm that the specified
amount is discharged.
Specified discharge:
(3 min/1 cylinder)
50 hp:
1.90 ± 0.50 cm3 (0.064 ± 0.017
US oz, 0.067 ± 0.018 Imp oz)
60, 70 hp:
2.20 ± 0.50 cm3 (0.074 ± 0.017
US oz, 0.077 ± 0.018 Imp oz)
75, 80, 90 hp:
3.10 ± 0.70 cm3 (0.105 ± 0.024
US oz, 0.0109 ± 0.025 Imp oz)
NOTE:
Oil temperature: 10 ~ 30°C (50 ~ 86°F)
- Before measuring, bleed the pump completely
and ensure no air-bubbles are
present in the oil flowing out of the oil
feed pipe. - When measuring with the measuring cylinder,
ensure that no oil clings to the cylinder
wall, otherwise the measurement
will be inaccurate. - Use only genuine Yamaha oil. If the viscosity
is too high or too low, the measurement
of the discharge will be
inaccurate. - The longer the time over which measurement
is made, the more accurate will be
the measurement. Calculate the rate of
discharge per minute.
I can tell you from personal experience with a 89 yami 150 I have that when the oil pump begins to malfunction you will see oil dripping down the leg of the motor out of the cowl.
I replaced the pump and lines(with clear yellow) fuel line so I can visually inspect from time to time if it is oiling
Yamaha has one of the best oil injection systems IMO.
Ive removed and just premix on all other brand motors ive owned but the yami is still injected to this day and it is going on 28 years old
84 HYDRA SPORT 1800SS
89 Yamaha 150
‘BAD HABIT’
89 TRACKER 17 TX
MERC 50
‘OL LEAKY’
quote:
Originally posted by C Michael BergenI’ve got a '91 90 yammie. I filled the oil reservoir then ran it on a full tank of mixed gas for a few trips. Measured how much gas and oil it took to top off both tanks and did the math. Found that the oil injection system was only putting in100 to 1 ratio so I also run 100 to 1 in my tank now to get the proper 50 to 1. Works for me
if you are already having to pre-mix some, why not just delete the oil injection and go full pre-mix? then you can at least be sure you are getting the proper ratio.
Any 2 stroke oil injection that is 27 years old need to be made to run on premix! Then you don,t have to worry. I change mine over at 15 years.
I have a 50 2 stroke 1990 that my son runs on a 15 keywest.
it is oil injection
I wouldn’t think of disconnecting it.
Yamaha has the best oiling system on the market.
either way will tell you if the system is working.
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quote:
Originally posted by TheMechanicif you are already having to pre-mix some, why not just delete the oil injection and go full pre-mix? then you can at least be sure you are getting the proper ratio.
Yeah- I could have been clearer. My point being that just because you have oil running through the system you can’t assume it’s the right amount. As far as my case- I intend to fix the oil injection system on my boat but for now this is the workaround that has kept me fishing twice a week for the past 5 months or so.
John_boy - do you have a link to a source for the service manual? I have searched Google and found a couple aftermarket downloads that various people have said to stay away from, so far have not located the Yamaha original one.
Thanks.
Mike
I purchased one from SIM Yamaha. Its about 75 bucks but worth it if you do most of your maintenance yourself. Send me your e-mail through PM. I may can work something out for you.
quote:
Originally posted by DirtMikeJohn_boy - do you have a link to a source for the service manual? I have searched Google and found a couple aftermarket downloads that various people have said to stay away from, so far have not located the Yamaha original one.
Thanks.
Mike
the oil injection is SET AT THE FACTORY to inject different amounts relative to the rpm’s the motor is turning… THIS is the beauty of the system .
“If there are no dogs in Heaven, then when I die, I want to go where they went.”
Will Rogers
quote:
Originally posted by boatpoorAny 2 stroke oil injection that is 27 years old need to be made to run on premix! Then you don,t have to worry. I change mine over at 15 years.
Mercury had known failures from the plastic gear they used failing. I think they had a recall over it. Also I never liked the Johnson VRO. Other than that I’d never go to premixing. Yamaha like Chris stated has a fantastic oil injection system.
I sold a Susuki TS 250 (motorcycle) with oil injection that had several rebuilds and heaven only knows how many HARD miles. Never one issue with the oil injection. That’s nearly 40 years of flawless service.
“Why Bruce?”