Help us before my husband throws our Mercury outboard in the water!

May 17, 2004
5,032
Beneteau Oceanis 37 Havre de Grace
hmm, we don't know how to check it, but it seems the flapper is closed even when it is sitting there. Not sure if it is
The choke should be closed when the engine is cold and open as it warms up. If yours is staying closed that would cause the engine to run too rich and run badly.
 
Aug 2, 2018
96
Beneteau Oceanis 40cc Little River, SC
Please excuse my ignorance and this is not meant to be critical...but are you motoring a Bene 40CC with an outboard? Curious minds need to know. Coils should be checked for cracks in the polymeric encapsulant, as well as wire connection being loose. Extreme temperature swings can have a prolific impact on the plastic coating, as well as high humidity or rain ingress upon the coil. I still think this is a fuel flow issue.
HAHAHAHAHAAA! Good Lord NO, Our Beneteau has a 56 Yanmar.
But thanks for the great advice about the dinghy motor!
And for the chuckle.
 
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capta

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Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
The ends of the hoses where they fit on the tank (there's a spring loaded ball valve in there) or motor can get some contamination at that point. This would reduce fuel flow and could be at least part of the problem. Can you borrow a fuel line from someone?
 
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Dec 2, 2003
751
Hunter 260 winnipeg, Manitoba
Have you tried pumping the primer ball while it is starting to die? - also checked arrow on bulb to ensure it’s pointing to engine? I have had a motor with a small air leak in the hose that would die at heavier throttle and recover if primer bulb was pumped. Also had one that would idle/run at low speed with the hose reversed - primer bulb required replacement and hose rotation in this case.

Is there a fuel filter anywhere in the hose/tank - check for air leaks at hoses/seals. Any possibility of a slightly cracked line in the engine itself? - I’ve come across many hoses that have cracks right where they push onto fittings.
 
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Nov 30, 2015
1,337
Hunter 1978 H30 Cherubini, Treman Marina, Ithaca, NY
I had to make sure. 15 HP is a big motor for any dink! Guess a BU masters grad misses stuff like that in post #1, occasionally. LOL. I guess my training was in writing...not reading comprehension. Sorry, I’m watching the Buffalo Bills in pre-season and my focus is a bit off. Go Bills!
 
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Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
Yeah but skip the dual wheels. It causes too much stress.
 
Feb 10, 2004
3,919
Hunter 40.5 Warwick, RI
Well Cara, after reading through these two pages of posts, I can't think of any idea that has been left out. In my experience, fuel and ignition problems present with very similar symptoms. This makes it hard for us to figure out the exact problem. So I would do a test to try to determine if the problem is fuel or ignition.
It sounds like the problem is persistent and that you can observe the poor running by just opening the throttle under a load. The test is simple- Remove the cowling so that you can see the intake of the carb. Put some of your fuel mix into a small spray bottle. Run the engine so that it starts to die and then spray a short burst into the carb. If the engine continues to die then the problem is likely to be ignition. If it recovers and runs strong for a few seconds, then the problem is likely to be fuel.
Once you have the problem diagnosed to either ignition or fuel then you can concentrate on the answer.
I suspect that you will find that the problem is fuel-related. After you spent $300 for a mechanic to rebuild the carb and it still ran poorly, did you return and tell him that his repair was not effective? What response did he have?
Regarding the use of E0 gas, my experience is that all of my small engines (outboard, string trimmer, blower, chainsaw) are happy to run on this fuel with no problems. I have no experience with TruGas which also has no ethanol. So my opinion is that if it runs badly on E0, it will probably run badly on TruGas. But YMMV.
If the problem turns out to be ignition, a possible cause that hasn't been mentioned is a bad ignition module. These small engines often have a ignition module that fires the coil but also adjusts the spark advance depending upon engine speed. A faulty module that does not advance the spark will also cause the symptom you describe. But I still put my money on fuel being the culprit.
 
Jun 11, 2011
1,243
Hunter 41 Lewes
Just because a mechanic bolted in a new carb doesn't mean he checked the float adjustment which is critical to both idle and Wide Open Throttle. Idle can be fudged but WOT can't. An air leak does sound plausible also.
 
Aug 13, 2012
533
Catalina 270 Ottawa
Just to be sure...

if this is a 2-stroke - you do use the right mixture of gas and oil, don't you? I have seen a 2-stroke die when getting hot, when the oil to gas ratio was too low (the engine was seizing).

I would also triple check the fuel filter (I know that you mentioned that you did replace it, but the fact that the symptoms went away after replacing the gas tank and lines (new gas!) could point in this direction). I had very similar symptoms when the filter was clogged.
 
May 24, 2004
7,129
CC 30 South Florida
Rather than put $300 into the old carburetor, he should have replaced it with a new one. Some of these gummed up carburetors cannot be repaired. I'm not saying this is the problem but the carburetor should not be eliminated as a possible source of the problem during diagnostics. Kloudie mentions a good point, check the coils as the symptoms are consistent with fouled coils.
 
Jan 27, 2008
3,045
ODay 35 Beaufort, NC
Believe it or not but the fuel line squeeze bulb should be mounted in a vertical orientation with the arrow pointing up. A few zip ties on the hose will help mount it this way.
"by choogenboom » Aug Tue 25, 2009 9:34 pm

I have been experiencing occasional (twice in last year) situations where when its really hot (95 degrees) and I run the boat, moor it for an hour, and then run the boat again one engine dies of fuel starvation. Yamaha customer support clued me in to looking at the primer bulbs, and the continuous wave web site had an article that confirmed my suspicions that primer bulb orientation matters. I finally (hopefuly!) traced the problem to the primer bulbs having a horizontal orientation. In fact they were oriented with a slight downhill slope, when referenced to the fuel flow direction. The check valves need gravity to operate so if the bulbs are pointed downhill the valves will stay open and allow fuel to flow back into the tank and air to get into the fuel lines. The result is the engine dies of fuel starvation. So moral of the story - check the orientation of your fuel primer bulb and make sure the fuel flow arrow is pointing skyward.
2004 330 Express w/ twin Yamaha F225
1994 228G w/ Yamaha 250
2008 Boston Whaler Ventura w/ 150 Verado
choogenboom
Posts: 101
Joined: Sep Fri 19, 2008 1:43 pm
Location: Beaufort SC"
 
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Aug 2, 2018
96
Beneteau Oceanis 40cc Little River, SC
I had to make sure. 15 HP is a big motor for any dink! Guess a BU masters grad misses stuff like that in post #1, occasionally. LOL. I guess my training was in writing...not reading comprehension. Sorry, I’m watching the Buffalo Bills in pre-season and my focus is a bit off. Go Bills!
You are forgiven :biggrin:;)
 
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Aug 2, 2018
96
Beneteau Oceanis 40cc Little River, SC
Well Cara, after reading through these two pages of posts, I can't think of any idea that has been left out. In my experience, fuel and ignition problems present with very similar symptoms. This makes it hard for us to figure out the exact problem. So I would do a test to try to determine if the problem is fuel or ignition.
It sounds like the problem is persistent and that you can observe the poor running by just opening the throttle under a load. The test is simple- Remove the cowling so that you can see the intake of the carb. Put some of your fuel mix into a small spray bottle. Run the engine so that it starts to die and then spray a short burst into the carb. If the engine continues to die then the problem is likely to be ignition. If it recovers and runs strong for a few seconds, then the problem is likely to be fuel.
Once you have the problem diagnosed to either ignition or fuel then you can concentrate on the answer.
I suspect that you will find that the problem is fuel-related. After you spent $300 for a mechanic to rebuild the carb and it still ran poorly, did you return and tell him that his repair was not effective? What response did he have?
Regarding the use of E0 gas, my experience is that all of my small engines (outboard, string trimmer, blower, chainsaw) are happy to run on this fuel with no problems. I have no experience with TruGas which also has no ethanol. So my opinion is that if it runs badly on E0, it will probably run badly on TruGas. But YMMV.
If the problem turns out to be ignition, a possible cause that hasn't been mentioned is a bad ignition module. These small engines often have a ignition module that fires the coil but also adjusts the spark advance depending upon engine speed. A faulty module that does not advance the spark will also cause the symptom you describe. But I still put my money on fuel being the culprit.
So much GREAT info here. wow, thank you thank you thank you
 
Aug 2, 2018
96
Beneteau Oceanis 40cc Little River, SC
Just because a mechanic bolted in a new carb doesn't mean he checked the float adjustment which is critical to both idle and Wide Open Throttle. Idle can be fudged but WOT can't. An air leak does sound plausible also.
good point, we are checking that out.
thanks!
Cara