Yamaha 4-Stroke Not Getting Gas

[pahagen]

2000 9.9 Yamaha 4-Stroke runs no longer than 5 minutes at a stretch without killing -- Unless at full throttle. Pumping bulb allows restarting, but same problem repeats. This is a "kicker" and not operated by tiller, so this is very annoying when trolling. Any ideas or suggestions?

[Guest]

I'm guessing the fuel pump went.
Any gas hose that's kinked, or poor ventilation from tank to motor?

[Ely Lake Expert]

Pahagen, I had a similar problem and all the only thing wrong was a bad connection between the gas tank and gas line. Take a look at that.

Ely lake expert

[pahagen]

We've had the darned thing serviced twice already in 2 years. Each time the dealer "resolved" the problem but they were wrong. If it was a fuel pump problem, would the motor work running at full throttle? We checked the fuel line and saw no obvious problems with the exception that the line itself is, in our opinion, exceptionally long with a big loop.

Thanks for all the suggestions, we're getting frustrated.

[Ely Lake Expert]

Pagagen,

Did you check both connections? The one to the tank and the motor. I would also try hooking it up to a different gas tank if at all possible. The gas tank itself could be bad. That is all I could imagine would be causing this problem.

Ely lake expert

[pahagen]

Our boat is a 2000 Alumacraft with only one gas tank. The 175 hp works perfectly fine and the "kicker" works perfectly fine when at full throttle. When we use the kicker at less than full throttle it constantly chokes. Could it still be a gas line, gas tank or fuel pump issue?

[wishing for walleyes]

could it possibly just be the breather screw on the tank is shut?

------------------
Dan

[pahagen]

Thanks everybody... We have a 19' boat with a built in tank, approximately, a 40 gallon capacity. We suspect this may be a fuel pump design issue or problem. (Fuel efficiency so high motor doesn't draw fuel fast enough to create adequate suction).

What's bugging us is that we're sure there are a lot of 2000 Yamaha 9.9 4-stroke engines out there. Are we the only ones having this problem? If not, has anyone heard about a fuel pump retrofit or some other solution to this problem?

Thanks again...

[Ely Lake Expert]

Pahagen,

In an earlier post you said that you are running your 9.9 on the boat 40 gallon built in tank and I think that is the problem. Unless I am mistaken, I think a 2000 yamaha 9.9 hp four stroke is supposed to run on a 100:1 gas to oil mixture. I could be very wrong, but I would definately take a look at this if i were you.

Ely lake expert

[Guest]

I run a kicker on my Alumacraft TP 170 and I had to splice a shut off valve on my main gas line. If you are running any other system, other than a seperate gas tank for the kicker, that may be your problem right there. If you don't have the proper fuel supply to that kicker, you are starving it with fuel and there is your problem (?).

What kind of fuel line system do you have running to that kicker?

Other than that I have seen fuel pumps do the wierdest things. That might be another option.

And, no, don't mix any oil with the gas on a 4 cycle engine!

[Scoot]

I'm with CD and a previous post. I've heard that not putting in a shut-off valve can be a common problem as it doens't allow for adequate suction to a smaller 4-stroke. I run mine just like yours with no suction problem, but I've heard many people have problems without the valve in there. I'd look into this. If this is the problem it would act exactly like you are saying yours is.
Scoot

[Guest]

When you prime the bulbb after stalling is it soft?

If so, you have a bad check valve in your primer bulb.

I would replace it with a regular OMC primer bulb rather then the Yamaha primer. OMC seems to hold pressure better.

PCG

[pahagen]

CD and Scoot,

I'm not sure I understand what you mean when you said you had to splice a shut off valve to your main gas line. We do have some sort of valve that we turn whenever we switch motors. I believe that it is cutting the gas off to the motor not in use because the bulbs go flat.

Also, you asked what kind of fuel line system we are running to the kicker. I don't know the answer to that either. Sorry. I did however, post pictures of our motor setup to the web. If you get a chance would you take a look? Maybe you will get the answers you're looking for.

I'm still crossing my fingers that someone out there will know what's going on and appreciate any advice offered.

www.imagestation.com/album/?id=4291492385

[WarrenA]

If the bulb goes flat then I would say that the problem is between the bulb and the tank.I would start with the switch valve. You may be able to get one a auto supply store. They used to sell auxillary tanks for pickups and they had a switch valve simular to the one in your pictures.

[Valv]

Don't take it as an offense, but what do you look at the fuel switch, the long "handle" or the small tip?
Open line should be the small tip of the switch.
Also can it be possible to switch lines while in water (with quick connector) or it's direct into motors ?
This might help deciding if it's motor or fuel line.

[Scoot]

Sorry, I don't know what to tell you beyond the suggestions you've been given. As suggested above, try figure out if it's fuel/fuel line or motor. I think it's in the supply area- aka. fuel/fuel line. Try the suggestions above and if they don't work start asking for the most reputable boat mechanic in your area.
Good luck,
Scoot

[Guest]

pahagen-
Great pics!
To answer you questions the best I can:
I had to literally cut my fuel line and splice in a shut off valve (identical to yours) on the outside of the boat, about 1 foot from where the hose enters the motor. It was the only way I could get it to work. It is a 3 way valve (3 ports off of it, one to the left, right and one on the bottom of the valve.
Is yours a three way valve?

On my boat....my valve MUST be turned so the little arrow on the valve points towards the kicker motor....that will give all the fuel to the kicker and shut off the fuel to the main motor. The arrow on the valve must be pointed to the left for the main motor.
In your close up picture you provided of the valve, then that will be to the kicker....granted I am viewing a pic looking from inside the boat, towards the motors. You will forsurely know which is which because either motor will run out of fuel in a hurry!

Is your fuel line for the kicker spliced off the main fuel line to the 175hp? Follow the main gas line and find out the path of all your fuel lines. Make sure it isn't sliced off the tank itself...some boats do that (no real need for a shut off valve).

[LundExplorer]

Try a separate small tank with shorter line, this might help in isolating whether its a fuel tank/line or motor problem.

TL

[kwkfsh]

sorry to hear about your problems with your 9.9. I have one also and and it has always run great. I am not using it currently but had it on an IB jetboat with a built in tank and had the fuel line from the tank run to a water seperating fuel filter. the filter had an inlet and 2 outlet ports. I ran 1 fuel line to main engine and 1 to the kicker. this eliminates the need for a valve.(nothing to fail or forget)Plus this can save much trouble should water get in the fuel. (bad gas or condensation) It sounds like you have an air leak in the fuel line. It could also be some water in the tank. It would not hurt to put a bottle of ISOHEET in the tank. The isoheet in the red bottle is isopropyl and is easier on rubber and gaskets than the heet in the yellow bottle which is methanol and has a tendancy to dry that stuff out. Racor has the best filter as it has a drain on the bottom to check for and remove water. (about $60) or OMC has a kit with no drain or bowl just a spin on filter. (about $30) hope you get it figured out!

[Bob O]

You said the main motor's primer bulb goes flat when you are using the kicker motor (and vice versa)? Your switch valve should also act as a shutoff valve, so one motor cannot suck gas from the other. It sounds like your valve is not designed that way and may need to be replaced with a different design. I believe it is also possible to replace the valve with a special T-connector that has built-in check valves so you don't have to manually throw the switch. A knowledgeable dealer could answer that question and sell you the connector.

I live in NE Plymouth. If that is close enough for you, you can borrow my 3 gal tank with a Yamaha fuel line and try it with your kicker (I have a 4 stroke Yamaha 8 hp kicker). That will confirm whether the problem is with the motor or fuel system.

Following up on one of CD's comments: Does the valve really switch between the two motors or is it simply a shutoff valve for the kicker? It should have 3 hoses connected to it. Is there one coming into the bottom of the valve from the fuel tank? We can't tell from your pictures. The two lines coming out the sides of the valve should each lead to a motor. If that is not the case, then you may have been shutting off the fuel supply to the kicker.

However, I still expect the problem is with the design of the switch valve. The main motor primer bulb should not be able to go flat because there is no place for the gas in it to go if the valve has properly isolated it from the tank and kicker motor.

As a side note, someone else pointed out that the primer bulb has a built-in check valve (intended to prevent gas from draining back into the tank whenever the motor is shut off). I expect that valve is between the bulb and the engine and thus does not prevent something from sucking the gas backwards out of the bulb, which I think is what your kicker motor is doing to the main motor's fuel supply.

[This message has been edited by Bob O (edited 08-23-2002).]

[Fireguy]

My dealer told me you need an anti siphon t valve to connect a kicker to your main tank.

[MnIceman]

I'd check every fitting back to the tank. A very small air leak can be the cause to lose suction at low consumption. Nothing should be even a little loose (hose clamped on the barb,threaded fittings,etc.).Do you have to prime the big motor after it sits for an hour or so? Then it is an air leak somewhere or a leaky check valve in the primer bulb for the big motor. Which I'm assuming that the switching valve does not seal 100%, so the air leak would be the primer bulb check valve on the big motor. Which would be why you could re-prime the small motor because of the larger pumping action. Good Luck !

[This message has been edited by MnIceman (edited 09-01-2002).]

[pahagen]

Wow! Thanks everyone for your responses. We haven't had a chance to look into anything as my Grandma recently passed away (97 wonderful years). Anyway, we will be checking out all of your theories soon.

One question asked that I DO know the answer to is that the primer on the big motor does not go soft when the valve remains pointing to the big motor. It only goes soft when we switch the valve to the small motor, then we need to reprime when going back to the big motor.

Lots to look at, but really appreciate all of your responses. This is more information than we received from our boat dealer.

[Guest]

K.I.S.S.

Keep It Simple, Stupid.

First thing to do is get a 6 gallon can, and a seperate fuel hose, and run the 9.9 that way.

That will narrow your field of possibilities in a short matter of time.

PCG