1995 Yamaha 9.9 HP low hour, too low?

[Jerry_NJ]

I looked at a 9.9 hp Yamaha 2cycle outboard engine that is about 17 years old and is characterized by its owner as having only a few hours on it. It looks that way too, removing the engine cover shows a spotlessly clean engine. It didn't start on a few pulls, I didn't try more but plan to try to check it out further. The low usage of the Yamaha was because the boat owner also has a 4cycle 25 hp engine that is the engine of choice for this boat. There are a few lakes in NJ that limit hp to 10 hp, thus the 9.9 hp, but it seems he rarely used the boat on those lakes.

What should I look for? Is there such a thing as too few running hours, perhaps rust inside, and/or seals dried out, carburetor gummed up (even if run dry after each use?) or hardened varnish from long periods of sitting dry. Is this less of a problem in 2cycle engines than for 4cycle engines?

I have heard elsewhere that the water pump impeller (soft/rubber?) can be damaged by sitting dry for long periods - it was even related to me that Yamaha has more than its share of problems with the water pump - again I think just the impeller as it gets power from a taps into the drive shaft to the prop, right? I was told the water pump needs to see preventive maintenance (replacement) every 3 to 5 years.

If the engine starts, that would seem to give the fuel system a passing grade, is there something to look/listen for or if the engine runs smoothly is that enough? What is the best way to check the water pump short of disassemble.. that said is there a good thread on discussing replacing the water pump on a small Yamaha OB from the 1990s?

Is there a consensus on the general quality of a 1995 9.9 HP Yamaha? Assuming it is in great condition is it worth $500 or more?

 

[Capt Ken]

Re: 1995 Yamaha 9.9 HP low hour, too low?

Check the compression and fire to the plugs. If that is good, then its good to buy. You will need to clean the carb, replace the diaphram in the fuel pump and the water pump impeller just due to age. I just sold a 4hsp 4 stroke for $500 but it was running.

 

[Jerry_NJ]

Re: 1995 Yamaha 9.9 HP low hour, too low?

Thanks, is the diaphragm fuel pump in the carburetor or is it a stand alone fuel pump?

I understand the model number on the engine shows the year of Manufacturer, by the letter ending the number, and that a 1995 ends in T, a 1996 ends in U, and so on up to X for a 1999, can anyone confirm or correct?

Is there a good generl source on small OB mechanics and parts break down? I can usually tell by an "exploded" view for parts how to take something apart and put it back together again. How about a something like is available for various automobiles by Clinton and Edmonds (sp?) ?a

Edit: I found some maintenance and repair manuals at my local public library... I may have used them a couple of years back when I had an ignition problem on my 1995 Evinrude 9.9 2Cycle I also received some good help from "iboats"... I had to change the ignition module, go figure, a fully electronic ignition failing : (

 

[Jerry_NJ]

Re: 1995 Yamaha 9.9 HP low hour, too low?

Just got a telephone call from the seller of the package, 1995 Discovery 14' fishing boat (flat interior with deck/carpet/live-well/nice) and the rarely used Yamaha 9.9 HP. He said he put in fresh gas/oil and the engine started right-up. I expressed concern about he parts that age without use, e.g., the water pump. He said he can demonstrate the pump has good pressure with rabbit ears on the water intake - does a good solid stream out of the "pilot" hole on the engine indicate a good pressure? I know to always check when starting an engine that there is water flow, or shut down pronto. Buying the boat m short Evinrude can not be used on the boat, and they are selling as a package anyway - see Craigslist sale below.

1995 14ft Discovery Voyager fishing boat with New 9.9 Yamaha

I'm beginning to "feel" the engine which looks new, is a good buy if it starts easily and if there is a solid water stream out of the water jacket indicator hole/pilot. I'd think a bad/weak fuel pump diaphragm or problem carburetor would not start easily... even if it had just been started before I arrive to make a test.

Off topic, but still boating, can one get a good indication of the state of marine plywood under decking by tapping with a ball-peen hammer? Is there a better check? One risk one has buying a boat out of the water is leaks, but this boat has a very good looking aluminum hull - not to mention Yamaha which is shown mounted in one of the listing pictures.

 

[Jerry_NJ]

Re: 1995 Yamaha 9.9 HP low hour, too low?

Made another visit to the used boat sale as they got the 9.9 Yamaha running. Said fresh gas and oil did the trick and that the water pump was delivering water to the test output at the lower rear of the engine compartment. He had it hooked up to a garden hose and the clamp on earmuff like engine water supply. These earmuffs were camped across the lower part of the engine drive shaft just above the prop area. Very little water was coming out, he said I should feel the air stream coming out.. in my experience with OMC (johnson and evenrude) there is a very visible stream of water when the engine is running. He pointed out the water intake on the Yamaha is facing downward toward the prop, and is not on the sides where the earmuffs were clamped. He ha opened a small hole on the side for water to get in, and that's the reason the pilot/check stream was so anemic. He said we'd have to put the lower engine housing into a drum full of water to get a true test of the water pump. Any views on this for the Yamaha? It appears the Yamaha requires a different type of water supply adapter if it is to be feed from a garden hose.

The engine was smoking quite a bit, I assume it is a 50/1 gas/oil mix... seems to me that is typical and the smoking drops back whtn the engine reaches operating temperature.. right?

 

[Jerry_NJ]

Re: 1995 Yamaha 9.9 HP low hour, too low?

I purchased the used boat package including the 9.9 HP Yamaha. It appears to be a 1993, and may need a impeller replacement. It will not see any in the lake use for a few months. The seller said he had the oil at 32:1 and that may be best for now, and that will produce some very visible smoke when the engine is cold.