Small outboard bad running tip

Pirate Lady

Pirate Lady

Well-Known Member
Jun 2, 2020
7,553
Chesapeake Bay, Middle River
Boat Info
Sundancer 250 ‘91
Engines
7.4 Bravo 1
Posting this as info in case you ever encounter this. Last Friday i ran the zodiac all over. Got back and filled the in-motor tank as i always do after a run. Wednesday i plan to go for a ride.
Engine will only run when choke out on full, push choke in it dies.
Well we have an OB shop at marina so i walk up, tell the guys what going on and before i can finish the sentence he says water in gas.
Well that makes sense cause after the ride I empty the gas can into engine tank. This motor dont use much gas so the can got condensation.
Today, I drained the engine tank, ran it til it died from using all the bad gas in carb.
Filled fresh gas with stabil. After 20 mins it finally settled down and ran like a new motor.
Bottom line. I wont fill my 1.5 gallon gas can full and keep in dock box anymore. Will get .5 gal at a time which is good for 2 refills of motor tank.
Fresh Gas Matters.
 
The little things we don’t consider until they happen.
 
Pirate Lady said:
Posting this as info in case you ever encounter this. Last Friday i ran the zodiac all over. Got back and filled the in-motor tank as i always do after a run. Wednesday i plan to go for a ride.
Engine will only run when choke out on full, push choke in it dies.
Well we have an OB shop at marina so i walk up, tell the guys what going on and before i can finish the sentence he says water in gas.
Well that makes sense cause after the ride I empty the gas can into engine tank. This motor dont use much gas so the can got condensation.
Today, I drained the engine tank, ran it til it died from using all the bad gas in carb.
Filled fresh gas with stabil. After 20 mins it finally settled down and ran like a new motor.
Bottom line. I wont fill my 1.5 gallon gas can full and keep in dock box anymore. Will get .5 gal at a time which is good for 2 refills of motor tank.
Fresh Gas Matters.
Click to expand...
I have had the exact same experience last summer and this summer. The outboard starts to run like crap and turned out to be water in the gas. My marina guys dumped and flushed the tank for me for no charge the two times, but I wanted to prevent it. So I started to take the tank and put it in the boat cockpit (under cover) at the back near the door when I am away from the boat. There is enough air flow under and over the door that I don't get any fume build-up and it seems to reduce the water absorption from leaving it in the dinghy or on the swim platform while at the dock.
 
1A21D4C9-7E15-44F1-AE08-7BFC21F108C9.jpeg

Buying alcohol free gas and treating it goes along way toward eliminating water in your gas can. I can keep a 6 gallon can for most of the summer without water issues.
 
All gas in MD is ethanol. But i thought about this. Last time i got gas in this can may have been last winter. I use stabil, but cant honestly say how old this is. But no matter. Will get smaller amounts now. Took a nice ride this morning on a glass flat river with a smooth running outboard. Loving life.
 
Last fall I took the gas tank from the dinghy home and emptied it bit by bit into a clear 2Ltr soda bottle. The gas had been disturbed enough that it kind of looked like a urine sample - probably water in the gas. Capped it and turned it upside down. Left it overnight in the garage. The next day, in the bottom was water then clear gasoline. I kept the bottle upside down and took it to the driveway and began unscrewing the cap slowly until the water began to leak out of the loosened top while squeezing the sides of the bottle slightly until a bit of gas came out. The remaining gas was transferred to an empty jerry can. I've used that gas without issue all last winter and this summer for my snow blower and lawn mower. I didn't believe you could save old water soaked gas, but it would seem that you can!
 
NotHerDecision said:
Avgas is non ethanol. 100LL. Get it and you’re good.
Click to expand...

;) 100LL (100 octane low-lead) Avgas (aviation gas) for those who don't know. I used to buy 5 gallons at a time for home use when I used to putt around in a Cessna 172. My lawn mower and dirt bike LOVED it! Pretty much cleaned up the carbs on whatever motor had an issue. I have been thinking about going out to my local muni airport in the evening and swiping my CC and buying some again but its been a while and don't know if the protocols will let me do it. But definitely a good idea for storing some good gas long term as that is precisely what its for.

EDIT: Im not recommending anyone use 100LL Avgas in anything besides an air-cooled piston engine, such as an airplane. I have used it myself in chainsaws, weedeaters, lawnmowers, various 2 stroke and 4 stroke dirt bikes, etc. I would use it on occasion, sometimes to clean up something that was running rough or had been sitting a while and had bad gas. But it does seem to be very stable for long periods of time, unlike these modern ethanol blended gasolines. Please do your own research.
 
Last edited:
We have regional airport very near my marina. Are you saying i can go there and buy good gas a gallon at a time for the outboard? It uses 87 octane. What happens when i feed it 100 octane. Does it go on an acid trip? Serious.
 
See, I KNEW after I posted that (and thus the EDIT) I would regret it.

I am not the one who should give anyone advice on this. Have I done it myself, yes. Did I have any problems, no. But I really only used it occasionally.

The only real advantage I can see with using 100LL is that you can store it for long periods of time. Its really expensive, currently $4.59 gallon at my closest FBO in Northern CA. you can check your local price here: local.html
Your won't see any performance enhancement, in fact your outboard probably runs better on 87-93. Like I said above, I would run a tank or 2 on occasion through a small motor that had been sitting a while to clean up the carb, whether it actually did or not, who knows. But it felt like I was treating the thing to a nice expensive glass of champaign and maybe that is all it was.
 
Pirate Lady said:
We have regional airport very near my marina. Are you saying i can go there and buy good gas a gallon at a time for the outboard? It uses 87 octane. What happens when i feed it 100 octane. Does it go on an acid trip? Serious.
Click to expand...
You only need as high of an octane number as the engine requires, based primarily upon its compression ratio. Also, contrary to a number of opinions out there, a higher octane fuel does not run any hotter, nor does it burn faster or slower than other fuels. It only means that it's less likely to detonate prematurely (ping/knock).
That being said, you won't cause any problems with running a higher octane than what's required by the engine. Besides, avgas smells really good (as much as hydrocarbon fuel smell goes). Even my wife likes the smell of it!
Granted, it's been many years, but I was able to simply buy it at a small local airstrip and pack it away in jerry cans. Since your outboard requires 87 octane, load it up with a gallon of 80/87.
 
Our marina has nothing but ethanol free gas (mid grade and high grade), so for me it was not that. I think it was dew/rain and damp night air being sucked in the vent over time while the tank sat in the dinghy. Storing it in the cockpit seems to have solved it. I also add Startron to it when I think of it. Not always.
 
Creekwood said:
I think it was dew/rain and damp night air being sucked in the vent over time while the tank sat in the dinghy. Storing it in the cockpit seems to have solved it.
Click to expand...
You bring up a very good point. While storing during the off-season, I always try to have the tanks as full as possible in attempts to reduce their "breathing" during temp/weather changes.
 
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