Yamaha 30 bogging down

[Buckin Bronco]

I think I know what the issue is but I want to see what some of the more knowledgeable people have to say.

Haven't run the motor since May and it ran fine, ran all the fuel out of the carbs when I put it up.

Put new gas and seafoam in the tank although there was still a little bit of old gas left in the bottom. Ran it on Friday and it once it warmed up it idled fine no problems. Ran up river 1/2 - 3/4 throttle. Went to full throttle and after about 5 seconds it bogged down and died.

Cranked it back up and let it idle. Headed back to the landing at 3/4 throttle, made a sharp turn back up river and it started bogging. Kept revving through the turn and made it. Hit full throttle and it died again. Cranked it then idled back to the landing.

What is the issue? Trash in the jets? Water in the fuel?

[RazMaTaz]

Possibly a clogged high speed jet.

[Phone Man]

Trash in high speed jets. Mine did same thing. I had brand new mercury grey fuel line and the inner layer broke down. Bought black rubber fuel line from NAPA and ran a bottle of mercury power tune through motor and works fine now for 2 years

[KRT]

Most of the time when you have a carb bogging it’s the jets or the actual nozzle the jet goes into.

[Buckin Bronco]

Just drained the new gas and its pretty milky. Bout to try a clean tank with fresh gas.

[Will1982]

I’d replace that grey ethanol fuel line if you have it. Mine was doing the same thing and finally figured out that’s what it was. Found it in the screw off filter and it feels like a clear grit. I replaced with black fuel like from an auto parts store like phone man said. I also replaced the motor side fuel lines with tygon lines that you can buy on amazon. Just take a piece of yours off and take an inside and outside measurement so you know what to order. I cleaned my carburetors too. It has ran great ever since.

[Buckin Bronco]

I’d replace that grey ethanol fuel line if you have it. Mine was doing the same thing and finally figured out that’s what it was. Found it in the screw off filter and it feels like a clear grit. I replaced with black fuel like from an auto parts store like phone man said. I also replaced the motor side fuel lines with tygon lines that you can buy on amazon. Just take a piece of yours off and take an inside and outside measurement so you know what to order. I cleaned my carburetors too. It has ran great ever since.

Already has black fuel line and tygon lines. The gas looks terrible, I'm about to start over with a different tank.

[Will1982]

If you park it outside I’d consider one of those water separator filters that goes on the gas tank side. My brother had trouble out of his 4 stroke mercury and put one on and it has ran great for years.

[willyworm]

I've suggested this before, and I don't think it's your problem but keep it mind. Most tanks have a manually vented gas cap. I'd close mine all the way when I'd store the boat so the moisture in the air doesn't enter the tank and eventually the gas. If you don't open that vent cap up the fuel can't flow into the carbs as fast as the air can come into the tank to replace it and it disrupts fuel flow. I had a similar problem happen one day where I could run at idle all the way to half throttle but not wide open. Didn't figure out till I was done and loaded up to head home.

That's yet another reason to store your gas tank at full.

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[FishSticker]

Try manually choking the motor when it bogs/stumbles...if it pick's back up than you have a carb situation, more than likely clogged jets. On those 3 cylinders it is more than likely the bottom cylinder. If you are going to let those motors sit for an extended period of time, open the drain screw at the base of each carb...10mm IIRC.

[Buckin Bronco]

Try manually choking the motor when it bogs/stumbles...if it pick's back up than you have a carb situation, more than likely clogged jets. On those 3 cylinders it is more than likely the bottom cylinder. If you are going to let those motors sit for an extended period of time, open the drain screw at the base of each carb...10mm IIRC.

I normally do that, last time I ran it, it slipped my mind. Can you clear the jet without taking the carb apart? I ask bc I’ve never taken one apart and don’t want to mess something up.

[willyworm]

I normally do that, last time I ran it, it slipped my mind. Can you clear the jet without taking the carb apart? I ask bc I’ve never taken one apart and don’t want to mess something up.

Only way is to take em apart. It's easy. I'm sure there's a Youtube video of it out there.

[Buckin Bronco]

Took the carbs apart. Was able to get the small jets out. Couldn’t get the big jets out however. There were no blockages in the main hole of the big jets but since I couldn’t get them out I’m not Sure if the holes on the sides were blocked. Will get new gas tomorrow and run test it.

[Redleg Camo]

Make sure to re sync carbs. Believe air mixture screws are 2-2.5 turns out.

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[Buckin Bronco]

Make sure to re sync carbs. Believe air mixture screws are 2-2.5 turns out.

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I don’t think I touched the air mixture screws? Re sync the carbs? This is why I don’t do this shit.

Also this has had the oil injection removed.

[KRT]

The side holes are the nozzle the jet goes into. Those are the holes that I see clog. I blow them out with compressed air and use a needle to run through them.

[Buckin Bronco]

The side holes are the nozzle the jet goes into. Those are the holes that I see clog. I blow them out with compressed air and use a needle to run through them.

How do you get the big jet out?

[Buckin Bronco]

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Is this the air mixture screw?

[Redleg Camo]

yep, thats it. you really should pull the carbs completely off and clean them all. used to do mine about once or twice a year. 5 times for the zuki i had. it's been a couple years so im a little rusty on all the innards.

to re sync, you have to loosen the screws that connect the accelerator lever (the rod that connects all carbs). when all carbs are completely closed, tighten screws. Youll want to back out idle screw first. after you sync, reset idle.

something like that...

[Gone South]

The side holes are the nozzle the jet goes into. Those are the holes that I see clog. I blow them out with compressed air and use a needle to run through them.

While this is important to check cause it's usually the first to stop up, that's the slow speed jet not the main jet. Sounds like a main jet fuel delivery issue to me.