Motor cutting out 25hp Johnson

I had my motor out for a 10 min test ride last week and it ran great. Went fishing last night and after about 5 min it start to cut out. If I pump the bulb it it would then run fine for a min then repeat the same process. The gas line is new (and yes it was on the motor last week when it ran fine), the only thing that is different from last week is I added some gas and seafoam to the tank. After we stopped to fish the motor would start fine but when I gave it some gas it would kill. I had to just play with the throttle to get it going then it would open up and start cutting out again unless I pumped the bulb. Any ideas? This is a 25hp Johnson

Thanks DW

Sounds like the check valve in your primer bulb went out. May be easy as replacing the primer bulb.

Also;
Check your fuel filter. If the filter is clogged, fuel will bypass at idle. However, at “crack open” of the throttle, it will starve out. It will also starve out at high speed operation.

By pumping the bulb, you increase the pressure, “squeezing” fuel through the clog, enough to keep it running. If the filter is clean, I would check the carb, to ensure any debris did not pass the filter and block the fuel jets.

(I’m talking from personal experience )

I’d put money on the check vavle.

Gator Hunter

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I’d put money on the check valve.

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Primer bulbs can work fine one day, the next they are shot. I have even had them come out of the box new and not work correctly. I do keep a spare in the boat.

The percentages are high that the problem lies from the check valve back to the gas…although a leak or clog anywhere in the line will cause what you’ve described.

The primer bulb would be the first place to check. But there is a small chance that the tube that goes into your tank (and gas) may have a crack also. If you would have your tank sitting so that the crack portion of the tube was out of the gas…it wouldn’t run. If it was full or sitting so that the gas was covering the complete tube…you didn’t even know there was a problem….

Good Luck!

I agree with briank, I’d bet the fuel line inside of the tank has a crack in it. And you said outside line has been replaced,but its what inside that gets neglected,and forgoten. Out of curiosity let us know what you find please.

Your tank could not be vented properly. If the vent is plugged it will suck until the pressure builds up to much.

Your fuel pump could be shot. When you prime the bulb it fills the carb bowl but it’s the pump’s job to keep it full. If it fails you will have to keep priming it like you do to keep it running.

Deep water ,I totally agree with Jon on this one… same thing happened last year with my 25 mariner. Frustrating feelin for sure!!!

make sure the vent is open on tank , look for pinched gas lines or partally pinched under the hood , this will allow the float to fill slowly and when float is empty the motor is done , untill it filles again . or the sea foam could have loosend a small dirt particle and is cloging the small gas holes on the connector fitting

Another thing to check is the part of the hose that connects to the motor and the part where it connects to the gas tank. It might not be holding it tight to where it connects to the tank or motor. Had that happen one time years ago on a 25hp motor. Had to be towed to the boat landing and then hauled to boat to Smittys Marine and they replace the hose connecter and then it ran perfect. Somnetimes its something simple like that.
Thanks, Bill