1986 Pro V150 wont go over 2800rpms

I just bought this guy off eBay and am filling like I got screwed. He stated that the engine was running fine but then out of the blue dropped power. He got it back to shore, took it home, and called the marina and they 'told' him it probably just needed new plugs.

When I looked at the boat he started it on the muffs for me. It ran good and would rap out to 6K on the high idle control. Once I got it home I changed the plugs and dropped it in the water. It would idle fine but would not push more then 2800rpms.

He did have the oil injection disconnected and was mixing 50:1 thru the tank. He did not have any by pass wiring done to the OI, just had it unplugged and emptied. I have since tried to reconnect the OI by reconnecting the wiring. When I did this the low oil alarm would go off and it would not add oil to the main tank with the oil pump switch on the engine head. I hot wired the pump and it does work (runs) but is not moving oil to the main tank. I am going to clean the lines tomorrow and see if that makes a difference. Or, can anyone tell me the correct way of disconnecting the OI? If it's a hassel to fix I'll just do the mix in the tank.

So far I have: replaced the plugs, rebuilt the carbs, drained out all of the old gas (it had a ton of water in it) and pulled the fuel pumps (there are two) and looked them over. I found a little rust but no holes. I didn't like the rust so I have bought to new pumps and they should be here in a couple of days.

I am putting it back together tomorrow and, not finding anything that looked real bad, am anticipating no improvement.

Where should I go from here?

PS the motor is pushing 126-130psi from all 6 so that is not an issue

[boats.net]

To remove oil injection you need to remove oil and oil pump drive shaft from engine and install a block off plate over hole in block. plug off all oil injection pulse hoses at manifold and remove oil tanks and oil module. Mix 50:1 oil ratio in gas.

Thanks for the reply. I am kind of wondering if the disconnect of the OI is preventing the engine from going over 2800? I bought a service manual off of eBay and that turned out to be a burned copy on CD. I got it in the mail today and, has my luck would have it, it was broken in half.

Do these engines have a rev limiter that will prevent them from going over a set rpm if they are running low on oil or overheating? Is there a work around for this?

[boats.net]

If it signals a low oil warning the buzzer will sound and engine will go into rpm reduction, about 2000 rpm's.

[jb123]

you said it will run up to 6k under NO load...so it is a load issue which is usually carbs.

Yeah I thought about the carbs, that's why I took them a part. When I did I didn't find what one would call a lot of junk in them. That is why I went a head and bought new fuel pumps. I know on my street/stip car I can limit the rpms through my CDI control and thought that maybe Yamaha did the samething with their CDI system. BTW does anyone know if the CDI on the Yamahas are computer con*****ed? If so where is the con*****er located? Has anyone ever heard of one falling?

[marinerguy200]

baffled

I am currently working on a 1986 Yammerhammer pro v 150. Right off the trailer she hopps right out of the hole but then starts losing power. Once I set the rig back down and try to come back out the boat will start to come up on plane then sit back down.I have replaced the impeller and removed the thermostats from both heads also replace sparkplugs. I am lost we've never seen this problem before. No oil/heat horns, the boat can sit on the trailer for a few days and then repeats the problem.

Any help would be great

Thank you, Aaron