Dumb question from new-to-outboards

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Apr 21, 2011
4
Bristol 27 Baltimore
After many years on the water with diesels I downsized to a b27 and am coming up to speed on my 80's vintage Yamaha F9.9 four stroke outboard. Question is about the primer bulb. This spring the engine started and ran fine after the layup but the primer bulb disintegrated in my hand. Ethanol I guess or maybe they just do that after a few years.

I bought a new bulb and connected it to my plastic 6 gallon tank. The bulb pumps up firm but goes back to soft. The engine idles but stalls when turning up the throttle. There is no evidence of gas or gas smell so there doesn't seem to be a leak above the bulb.

Should the bulb stay hard? Is the new bulb defective? Does this mean an air leak in the fuel line below the bulb?
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Could be a couple of things.. If the strainer inside of the tank is fouled it would do something like that.. Generally, you can take out the pick-up tube and clean it and the tank to make sure everything is clean.. It could be a vacuum leak above or below the bulbcheck the o-rings and cleanliness of the connections to tank and to outboard.. Most of the time gasoline will not leak out but air can leak in.. Check the strainer and the lines inside the engine cowl to be sure they aren't cracked and leakiing air.. and last, check the fuel pump for cleanliness and springs and diaphragm in good shape.. Next is the carburator .. It may have dirty high speed jets/orifices, and or a dirty accelerator pump. If the fuel tank pump/lines clean-up doesn't fix it, then do the carb.. If ya not comfortable with clean-up of that, it is best to take the whole engine to a shop and get them to clean the carb.. After she is running OK, put detergent in with the fuel and consider finding a source of non-ethanol fuel.. Just went through this whole sequence with a friend's Yamaha 9.9.. She runs beautifully now..
 
Dec 11, 2008
1,338
catalina C27 stillwater
Is the new bulb connected in the proper direction? I know my question can be seen as insulting, but I have done it... :redface:

The symptoms you describe point to the bulb being installed backwards, such that the motor is sucking against the check-valve in the bulb.

Take a look at your new bulb and make sure that the arrow, (there should be one on it) is pointed towards your motor and not you tank.
 
Apr 21, 2011
4
Bristol 27 Baltimore
Not insulted. I wondered the same thing but the bulb is pointed toward the engine. Too bad because it would have been an easy fix.
 
May 24, 2004
7,129
CC 30 South Florida
The fact that bulb gets hard tends to indicate that it is working properly. Check for an air leak in the hose connector and tank pick up tube. It sounds like the engine gets enough gas to start but soon dies from fuel starvation. If the loss of pressure in the bulb occurs before the engine is started then it is an air leak but if it happens only after the engine starts then it is an obstruction. Clear fuel lines, fuel pump and carburator bowl.
 
Jan 22, 2008
423
Catalina 30 Mandeville, La.
I had some issues with my Nissan 8hp 2 stroke that hadn't been started in 5 years. I replaced the fuel line and tank and cleaned the carb and spark plugs. It would run but wouldn't idle well. I figured it would run a little better as I used it more. I could just rev it slightly and keep it running. I launched and couldn't keep it running well enough to get out of the launch. Luckily, it wasn't crowded. I had replaced the fuel filter with a basic lawnmower filter ( pretty much what Nissan uses anyway). It was slightly longer than the original and when tucked into position, it caused a bend in the fuel line. It wasn't kinked but bent about 60 degrees. That was enough to starve it for fuel. I moved it and straightened out the line and it ran like a champ and even idled smoothly. Hopefully, you have something simple like this.
 
Apr 21, 2011
4
Bristol 27 Baltimore
I think/hope the problem is solved. I basically followed the recommendations but not in the right order. I cleaned the carb first then the problem was unchanged so might have been able to skip this step but it was good experience. Made some adjustments to the idle which was higher after cleaning the carb then moved on to the tank.

The bulb came with two plastic hose clamps. Broke the first one putting on which should have been an indication. The connection at the tank was made with tie wrap. Those are both gone and the engine works like it should.

One lingering question. I could see the starter/choke plunger going up and down before cleaning the carb but now it doesn't move. I took off the sight glass and checked to be sure it is free but it doesn't move when starting the motor. The weather also got warmer. Is it a sometimes thing or should it move all the time?

Thanks for the advice.
 
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