1994 115 Mercury 2/4 Oil Injection

[Tregaskis]

Just bought was is supposed to be a great running 1994..115hp Merc 2/4 2 stroke...rebuilt the carbs because the old needles would not allow the bulb to get hard during prime. I now have 2 more questions...we had the motor professionally linked and synced and it idles like a 1934 John Deere tractor below 1000 rpm or so...shakes and vibrates and sounds terribly wrong. Is this normal for this engine? The boat shop says it is fine...the specs call for around 700 rpm in gear but that seems to barely want to stay running and in fact sometimes doesn't.
My main question is the oil injection. I ran the manual test on the pump and it is pumping well over the minimum specs in the book, but the oil tank never goes down when we are running. I have been running pre-mix in the tank to protect the motor but something somewhere is wrong. Their is a 2psi check valve that connects the oil pump line to the fuel line...when I tested I pulled the oil pump line off that valve instead of running the test through the valve like maybe I should have. Do these valves stick closed where they would stop the flow of oil out of the pump into the fuel line? Is there a source anyone knows of to buy a replacement valve? I haven't been able to find one online at all and my local stealer doesn't seem to want to dig out the older books to even look. Anyone have some help on this?

[boats.net]

They normally do idle rough.
The oil injection is a varable system, don't use much at low speeds. Mark the oil level in tank and continue to use pre-mix to monitor oil use, at full throttle should a 50:1 ratio but could be as little as 200:1 at idle.

[Tregaskis]

115 Merc Oil Injection and Idle

Thanks for the reply. I think I have found that the 2 psi check valve is stuck in the closed position so no oil is flowing from the pump...I have a new one and am installing it tomorrow and will retest. Now oil was flowing through the old one.
I also found another guy on here with the same idle symptoms mine has even up to the 1200 rpm where it smooths out...he found a bent reed pedal on one of the top 2 carbs. I am going to do a choke down test on the motor tomorrow and see if I can replicate his results...his ran smooth when only running on 1 of each of the top 2 cylinders but would shake and miss when both were running...choking of each of the carbs by hand showed him which one was bad. I will try that and see what happens. God, I don't want to have to pull the front of this motor off...but if that is the problem,.....