'87 200HP Oil Pump

[The Monkey Butler]

I am working on a 1987 200HP that I that I just got and before I attempted to crank it I noticed that the carbs were not closing fully. I found that they were being held open by the oil pump linkage. I have another motor that I compared the throw of the oil pump arm against and this one has much less range.

I can tell you that it is not a linkage adjustment problem, it is that the pump arm isn't swing far enough back to the closed or idle position. It doesn't look like there has been a wrench on the mounting pump bolts so I'm wondering if someone may have removed and reinstalled the arm incorrectly or if there is sometning internal on the pump that could cause this.

Any ideas?

[The Monkey Butler]

I pulled the oil pump off and discovered what the problem is. Apparently the shaft that the link arm turns is only held into the pump by the o-ring seal on the shaft. Mine is flattened and taken a set allowing the shaft to slip out of it's bore enough to cause it to hang up internally. I didn't see a part breakdown for the pump on this site or Yamaha's. Are parts for the pump available? I suppose I could try to find an off the shelf seal but I'd rather order the right thing.

Also, while browsing the parts diagrams it shows two different diagrams, one called simply "Oil Pump" and another called "Oil Pump Conversion Kit". Out of curiosity, what is the conversion kit? Is it an update or could you actually convert a non injected motor to oil injection?

[boats.net]

No oil pump parts are not available only replacement pumps. The original oil pumps were Keihin. About 1990 there was a conversion kit came with with a Mikuni pump, If yours has the Keihin pump it needs to be replaced with the conversion kit.