Restoring a disabled oil system on a V6 Yamaha

CharlieN

Cadet
Joined
Sep 21, 2011
Messages
7
I have a new to me '86 ProV 150 that some time in the past the oil injection was disabled. All the original parts are there. The oil line from the main tank was cut and inlet to the pump was plugged.
The oil feed from the under deck tank was also cut just before the connector at the engine housing. The pump under the deck tank still runs, I expect continuously till I unplugged the wires.
From what I have learned, and correct me if I am wrong, people were disabling this system due to oil bleeding into the lower carbs during storage causing smoky starts.

The cure for looks to be the oil pump conversion to the late style pump and incorporation of check valves inline the injection hoses.

Now where my question lye's, will just the installation of the check valves be enough to cure the problem or is there an issue with the early pump making the upgrade to the later style pump of great value?
What is the actual difference between the pump for the 150/175 and the 200hp pump?
Is there a later pump that is a direct bolt on for the pre 1990 engines or did the casting of the main case change with the pump change and the adapter and longer shaft are needed?
 

CharlieN

Cadet
Joined
Sep 21, 2011
Messages
7
Re: Restoring a disabled oil system on a V6 Yamaha

I found the information I needed on other sites to properly restore this oil system. I thought this site had someone who knew Yamaha outboards but I was wrong. I have all the parts I need on the way.
 

oddysea1

Petty Officer 2nd Class
Joined
Sep 22, 2011
Messages
190
Re: Restoring a disabled oil system on a V6 Yamaha

Any chance of sharing the other sites ,having similiar issues.
 

CharlieN

Cadet
Joined
Sep 21, 2011
Messages
7
Re: Restoring a disabled oil system on a V6 Yamaha

I have not bookmarked the postings I did my learning from but in simple terms, the 89 & earlier pumps have internal check valves. These were not sufficient to prevent oil from passing through the pump when not in use. Yamaha went to external check valves and a new pump design, the key item here was the new check valve design that provides a more secure stoppage of flow when shut off.

I expect you could get by with just adding the new style valves in place of the hose junctions but I found it economical to buy a used later style pump with hoses and purchase a new shaft and mounting adapter needed for the upgrade. This to me would be the best update to the system for the long term.

Once I had these installed and a gallon of fresh synthetic oil in the tank I soon learned the transfer pump would not turn off when the main tank was full. Turns out the control units were also prone to have issues and once mine was replaced all is good. I expect this would have been why the system was disabled by a previous owner more than the smokey starts the early pump was prone to.
 
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