Oil injection problem 1990 40hp

[Hobbes1945]

I am encountering a strange problem with my 1990 40 hp yamaha. I bought it brand new and have never had this problem.

The engine runs up to full throttle for only a short distance then it dies down and only goes about *****ing speed. Then after a min or so it can go up to full throttle again but then after a min it drops down again. It does this on and on. The oil injection tank on the side of the engine has lots of oil in it

The three led warning lights (green, Amber, red) for the oil injection on the bottom front face of the engine are doing this....
green light is on and as you start out the red light starts to flicker and then comes on red but the green light also stays on.

The engine temp light located to the right of these leds is fine, it is green. So not overheating.

Apparently there is a filter located inside the oil injector tank. I tried to locate a new filter but after talking to several dealerships it is no longer available.
Because of the age of the engine, it is impossible to find dealers who want to work on it. One even told me they no longer work on two strokes!

Any suggestions would be greatly appreciated. Thanks.

[TownsendsFJR1300]

Can you post the MODEL #?

There's several 40's, this one does show a filter inside the tank and is available (part #41):

https://www.boats.net/catalog/yamaha...tank-40er-40pr

[99yam40]

the lights do not indicate oil flow, just level in the tank.
I do not see that filter being a problem.
need to test the level switch and wiring

[Hobbes1945]

TownsendsFJR1300
the model number is. 40EMSG
6H4. S. 150238

Thanks for that link too, I will check that out.

[Hobbes1945]

Hi 99yam40
I couldn't figure out why they would want an oil filter inside the oil tank but the reason that seemed to be the culprit is because the owners manual says
"This engine is equipped with an oil filter clogging warning system. When a filter clogs up, the engine speed will automatically reduce to a safe rpm and the buzzer in the remote control box will sound. If the oil filter is clogged, it should be cleaned.". And then there is a note
"NOTE: this oil filter clogging warning system displays warnings similar to the oil level warning system and the overheating warning system. For easy trouble shooting, it is advisable to check for engine overheating first and then, check the oil level, and finally check the oil filter for clogging"

My unit does not give an audible sound as I don't have a remote control. I thought it strange that the green light was on indicating a full tank and the red light on at the same time indicating an empty oil tank. In the past I had noticed green and sometimes amber indicating a low level but never two lights on at the same time. And it never got below amber. The separate green led that shows temperature condition of the engine is always green. I have a very strong tell tail and a new waterpump impeller was just installed this spring. And as far as the oil filter clogging, I have never used anything but Yamalube in the reservoir. I still can't figure how a filter inside a reservoir ever gets clogged with anything. What would there be to clog it?

Thanks again.

[99yam40]

old oil and water condensate that can collect from the air can cause sludge.
Manual should have procedure on draining and cleaning the oil tank on some time bases

I never heard of a Yamaha that has a oil flow monitor.

I think I have read Suzuki does have a flow switch.
now the bigger motors that use more oil have a remote tank and the smaller one on the motor.
there is a oil pump that pumps oil to the motor tank as it lowers.
if the filter on that plugs up and not fill the motor tank then the alarm sounds as that tank gets too low

[TownsendsFJR1300]

TownsendsFJR1300
the model number is. 40EMSG
6H4. S. 150238

Thanks for that link too, I will check that out.

That model # doesn't show up in the parts section here as you must be out of the US.

99Yam seems to have you headed in the right direction in any event..

Good luck with it..

[Hobbes1945]

TownsendsFJR1300
thanks for your input, yes I am in Canada. It's strange though they have a model up here that wouldn't be available there.
I believe 99yam is on the right track.
Thanks again.

[Hobbes1945]

99yam40
Thanks for your help on this matter. I do have an interesting thing to report that backs up your suspicion that it is a wiring problem. I don't have a service manual but I do have an owners manual that is quite sparse on details.
Anyway yesterday afternoon I took the bonnet off to see if I could spot anything obvious. So most of my attention was on the oil reservoir on the engine and everything around it. I was trying to get an idea of the routing of all the tubing connected to the oil reservoir, the fuel filter and the pump. Everything is so tight, I was prodding and moving wiring and tubing in that location. I was reluctant to disassemble anything at this point in time as I was not at home but in quite a remote location. At any rate, I took the boat out last night and I dont know what happened but there was no sign of the red light flashing at all just the steady green light. And the engine was its old self again and ran like a racehorse. So obviously I must have disturbed something that was causing the problem. When I get back home my project will be trying to sort this out once and for all and at the same time I'm going to replace all the tubing connected with the oil injection system. I noticed yesterday it's getting quite brittle and hard.
so thanks again but one final question that I hope you can answer. On the cover of my owners manual it says it covers outboard 40D/50D/Pro 50D and in the specifications section I notice that the full throttle operating range, maximum output, bore and stroke, system displacement, ignition system, etc between the 40 and 50 hp models are absolutely identical. The only difference noted is the spark plug. So where does the 50 get the extra 10hp from?
Thanks again

[TownsendsFJR1300]

Extra HP as you described is a very common question.

If you look up and compare, side by side (major parts) those models, you'll often find carburetors are different, sometimes jetting, exhaust, etc...

[boscoe99]

TownsendsFJR1300
the model number is. 40EMSG
6H4. S. 150238

Thanks for that link too, I will check that out.

E model uses a strainer within the oil tank. Into which the float is mounted. If the strainer is clogged then oil cannot flow into the strainer assembly. In which case the float will drop. Float drops and the low oil warning system is activated.

http://yamahamc.partsandwarranty.com...1457543&Page=1

[Hobbes1945]

boscoe99
thanks for that Information.
is that link correct it's not working for me.

something else I just thought of is would it be advisable for me to run a 50:1 gas oil mix to protect the engine until I get it all sorted out? I sometimes wonder if it would be possible to totally remove the oil injection mechanism and just run a 50:1 mix from then on.
thanks again for your help

[99yam40]

E model uses a strainer within the oil tank. Into which the float is mounted. If the strainer is clogged then oil cannot flow into the strainer assembly. In which case the float will drop. Float drops and the low oil warning system is activated.

http://yamahamc.partsandwarranty.com...1457543&Page=1

never heard of that before, and your link did not work for me also

[boscoe99]

[QUOTE=boscoe99;n226562]

E model uses a strainer within the oil tank. Into which the float is mounted. If the strainer is clogged then oil cannot flow into the strainer assembly. In which case the float will drop. Float drops and the low oil warning system is activated.

https://www.boats.net/catalog/yamaha...tank-40er-40pr

[boscoe99]

never heard of that before, and your link did not work for me also

I have never heard that before either. Never seen it in any owner's manual. But I see it now. I am making a supposition. What else could it be?

Link fixed.