Weird fuel issue with my 4 stroke

Have a newish Yami 4 stroke that has been flawless but yesterday it was starting and killing. I pumped the ball which I have not done all year and made sure the line was not kinked and the air thing was open. When the ball was finally firm it ran far a while and killed again. Seemed to run if I kept pumping the ball which I should not have to do with fuel injection. Then at the end of the day for the last hour it was fine, ran evenly, started right up, idled well. What happened? Should I have it checked out?
Thanks

We are missing a little info, when did you pump the bulb? At the start of the day, middle of day after it had run, while it was running? Does the bulb run out of fuel while you are running? With the information given I would guess it is the bulb in the fuel line or the pickup pump.

Did not pump the bulb until it killed-last year do not think I pumped it once. Should the bulb feel full when running? I would pump that thing every time with my 2 stroke.
Thanks

Is it a portable or built in tank? A friend has a newer portable tank with a “safer” venting system. He has problems with it not venting properly and the motor stalling because it can’t draw fuel. His fix is to remove the cap and hit it a few times with a wrench or other handy object. He’s talked about drilling a hole in the tank and installing a tire valve stem so it can get enough air but I don’t know if he did it.

Pat K wrote:

Is it a portable or built in tank? A friend has a newer portable tank with a “safer” venting system. He has problems with it not venting properly and the motor stalling because it can’t draw fuel. His fix is to remove the cap and hit it a few times with a wrench or other handy object. He’s talked about drilling a hole in the tank and installing a tire valve stem so it can get enough air but I don’t know if he did it.

That is a good point, the newer portable tanks don’t come with a open/close vent, they have a relief valve in the cap. You can buy a cap with the old style vent screw in it still, better solution than drilling a hole in the tank.

The bulb should be hard when running, if not it could be leaking back into the tank.

The cap has a plastic thing that tightens and loosens, it is in the center of the cap. I’ll check that ball next time I go out when it is running. Irritating, was on a lake where all my spots are a couple of miles from the launch, fishing with a guy I have not fished with in over a year.
Thanks

check and I mean check every connection from the fuel tank to the motor, if you see any of them that look damp from a tiny fuel leak that means the primary pump can suck air there as well.
In the same sense you cant suck soda through a straw with a hole in it neither can your motor draw fuel through a leak in the fittings or hose.

depending on what size your motor is there is a cam driven primary fuel pump on the rocker box that pulls fuel from the tank and supplies the secondary or high pressure fuel pump, if it is getting air it will run like crap as its running lean.
another thing I want you to check is the tell tale hose, is the stream weaker than normal??
if it is weak the fuel cooler is not getting enough cool water through it and you will be boiling the fuel causing vapor lock and rough running.

you may think I am nuts suggesting an air leak in the fittings that mysteriously went away towards the end of the day but I have seen where the heat of the later part of the day can and will go cause the leak to go away when the fitting warms up and starts sealing correctly.

My motor is a 50 and only 4 years old pretty sure the pump is electric. The motor never ran rough it would just kill. I was not paying too much attention to the stream but I did think it was stronger when it started running better. wonder too if that hose could have gotten pinched. Lots for me to check thanks a bunch Iowa

Replace the primer bulb. Yhey go bad loose pressure and let fuel back flow. 20 bucks and 3 minutes of work.

And yes new tanks suck. I though I had serious issues with my erude, ended up being this new tank with no real vent. It expands and contracts like no other. I pull my line now every time I’m not fishing. Or even if I’m trolling with the electric motor

Not sure what you mean by ‘pull my line…’ Can replace that bulb easy fix, thing is only a few years old. Tank should be ok the vent seals and opens. Thanks Bear

tim hurley wrote:

Not sure what you mean by ‘pull my line…’ Can replace that bulb easy fix, thing is only a few years old. Tank should be ok the vent seals and opens. Thanks Bear

I pull my fuel line off the motor is what I meant.
It could be the on the motor side but I would replace the primer bulb first and try to run it. Then go deeper after that. Is the fuel filter clogging up ?

Is the vent off the cap still functioning properly.

Cheap & easy first, sounds good.

Replace the spark plug if you haven’t since new.

Iowaboy1 wrote:

depending on what size your motor is there is a cam driven primary fuel pump on the rocker box that pulls fuel from the tank and supplies the secondary or high pressure fuel pump, if it is getting air it will run like crap as its running lean.

tim hurley wrote:

My motor is a 50 and only 4 years old pretty sure the pump is electric.

As Iowaboy said, this motor has two fuel pumps. Only one of which is electric. The other is a mechanical fuel pump.

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Don’t start replacing fuel pumps until you’re done what Iowaboy said:

Iowaboy1 wrote:

check and I mean check every connection from the fuel tank to the motor, if you see any of them that look damp from a tiny fuel leak that means the primary pump can suck air there as well.

Air leak would always be my #1 suspect with those symptoms. Don’t be fooled into thinking an air leak in a hose is always easy to spot. I’ve seen them where the crack was so small that it was leaking air at a hose clamp without any visible fuel bleeding out. The leak was so small the fuel would evaporate so check very carefully at every joint or fitting.

Keep in mind, you can also have an air leak inside the tank with a crack in the fuel pickup tube. So even if you don’t have a leak in the hose, the tank needs to be looked at as well.

If there is any way you can find an fuel hose and extra tank that fits your engine, this is always a fast and easy way to see if an air leak or some other issues with the hose or tank is the problem. Start with the different hose and tank. If you don’t replicate the problem, try the old hose with new tank. Old tank with new hose, etc. Test each piece to see if you can identify which is the culprit.

I had that happen with my F250. Would stay running if I pumped the fuel line bulb. It was the low pressure fuel pump. I would start and sputter out. Low pressure fuel pump replaced on warranty.

Thanks! (did not know I had 2 fuel pumps) will check what IB said first.

This time the first part of my trip was fine but I had problems at the end-guess it did not fix itself (always my dream)Good thing I picked a small lake.

Sounds like you either are sucking to much air. Or your venting on fuel cap could be bad. Do you ever pull the line off, crank it over and re plug it in. If it’s expanding and over fueling it could be flooding it self

Update?

Called the dealership, glad I did because my warranty for that stuff is almost over, like in a few days, but the problem has been reported so I should be good as long as this is not my fault (like-how??) They are concerned because they are not sure they can easily replicate the problem, so it has happened twice, once right away and yesterday it was several hours into the trip, they would like me to go several more times to get more of a pattern-NO! Yesterday was ok because I was on a small lake, anyway maybe I will see If I can use a line from them to rule that out. Plus this Fs up my trip to Big Sandy, hope it can be rescheduled, and I hit a deer yesterday! Minor damage, insurance should cover it.

They replaced the fuel filter and are letting me try a new tank and line.

Ran perfectly did not need the tank and line-keep those fingers crossed.