2015 Suzuki 30 hp bogs as soon as it warms up, but works fine at low speed

[Ingmarz]

Hi all, we are into our 3rd year of regular daily use of our Suzuki DF30A and have not had a single problem until recently. We love this little motor! Now, the engine has started to bog at full throttle after about 10 minutes of running. It works just fine at low speed. I've got clean gas, new Raycor filter, checked the fuel lines, bypassed the Raycor, so now I'm stumped. Any suggestions? Cheers, Ingmar, Bella Bella, BC

[2014DF25ARS]

Is your motor tiller-control, or remote control? I have a DF25ARS with remote control about the same age, which is essentially the same engine. I had a fuel problem a year ago. My problem was not same as yours; my motor simply would not start...

You know there is an internal plastic fuel filter which is also a water-separating filter, and when I had problems I found that the internal filter was full of water, so I changed the internal filter. (Later I added an external Racor filter similar to you.)

I also found that one of the plastic valves inside my primer bulb was broken when my motor was about one year old. In my case, when I squeezed the bulb, I could feel something inside it, so I cut the bulb open and found one of the valves floating around inside! There should be a plastic valve fixed at either end of the bulb. You should not feel anything in the bulb except fuel. You say you have checked the fuel lines, but if you haven't done it already I suggest you try changing the primer bulb, or try removing the bulb entirely for a test.

You say your motor "bogs". What exactly happens? Does it start running rough? You know that several "error conditions" will cause your motor to limit the RPM, and I believe it does this by eliminating spark to one of the three cylinders, so it begins running very rough. In this condition, one of the "idiot lights" on the front of the motor should light, and if you have an NMEA2000 display (SMIS), it should display an error message.

[Moonlighter]

The other thing to check would be your fuel tank vent - it does sound like the engine may be starving for fuel after running at high rpm, and a tank vent that is blocked or not working properly will make it do that very much as you described.

You can test this theory by loosening the fuel tank cap and seeing if the problem goes away.

Also I would expect that the primer bulb would be sucked flat too when the engine bogs down.

[Ingmarz]

Thanks so much, Moonlighter! Problem solved! The motor was suffering from "teenageritis" -our 19-yr-old, -who, of course, has got nothing to learn from me, did the oil change recently and decided to re-route the gas line "to make it lay better" and used a zap-strap which put a kink in the line. I removed the zap-strap, and voila! Works perfectly now. He wasn't entirely wrong to do that, - the new gas filter he put in was slightly different than the original one, and the fuel line doesnt quite sit right. I solved this problem by rigging the zap strap in such a way that it doesnt kink the line now... Thanks for your help though! Glad to know this forum is here, although this Suzuki outboard has been flawless for nearly 3 years now!

[Hoosmatroos]

Haha, teenageritis. Once I was clueless with an engine, all new gas lines but at high throttle it bogs down. Owner already replaced all the gas lines but with a to small diameter. At high rpm's there wasn't enough fuel to feed the engine. Took me a while to figure that out

[Moonlighter]

Yeah, what would us old bast a r d s know hey!

The fact we had to fugure stuff out or ask our fathers for guidance rather than google the solution I think makes us better problem solvers (and avoiders) - I worry that the next gen havent learnt to solve problems themselves.....

Well done on picking up the fuel restriction!!

Cheers!