Attention Motor Mechanics....my 5 year old 6 HP Merc. ML has developed a problem. I can only keep it running my putting on full choke. The bulb seems to lose some hardness if I do not set full choke and then the motors dies. Might something be amiss with fuel pump? I priced replacement unit at $ 35 and will replace if someone can pin down problem as likely. Most appreciate your response.
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Scott Davis
Outboard motor
I am guessing that this is a 2 stroke outboard, but sounds to me that you are NOT getting enough fuel, as keeping the choke on, helps the eng to pull fuel and less air. Look for some kind of fuel clog, change filter if you have one. Not sure about fuel pump/type. Try to blow out fuel lines, clean carb out, look for stuck needle valves in carb. Pull spark plug after the eng dies and see if its Rich/excess gas, or lean/little or no gas. This should give you some idea whats going on. I would guess it also dies if you try to go faster or increase the load on the motor. Most outboards are still pretty simple eng's so keep the old air/fuel in mind. Scott
I am guessing that this is a 2 stroke outboard, but sounds to me that you are NOT getting enough fuel, as keeping the choke on, helps the eng to pull fuel and less air. Look for some kind of fuel clog, change filter if you have one. Not sure about fuel pump/type. Try to blow out fuel lines, clean carb out, look for stuck needle valves in carb. Pull spark plug after the eng dies and see if its Rich/excess gas, or lean/little or no gas. This should give you some idea whats going on. I would guess it also dies if you try to go faster or increase the load on the motor. Most outboards are still pretty simple eng's so keep the old air/fuel in mind. Scott
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Rick Webb
I Have the Same Outboard
Mine was doing the same thing you mentioned when it was cold. Last time I changed the impellor and the oil in the lower unit I also put new plugs and fiddled with the mixture screws now it starts on the first pull every time. May want to try that before the fuel pump. I will ask a buddy who is a Service Manager at the local Mercury dealer he knows these things real well. If he has anything to add I will post it here.
Mine was doing the same thing you mentioned when it was cold. Last time I changed the impellor and the oil in the lower unit I also put new plugs and fiddled with the mixture screws now it starts on the first pull every time. May want to try that before the fuel pump. I will ask a buddy who is a Service Manager at the local Mercury dealer he knows these things real well. If he has anything to add I will post it here.
Don't know if this might help, but...
I had a similar problem with a Tohatsu 5hp. If your outboard has a mechanical fuel pump (it's mounted on the side of the carb), you might want to check the neoprene diaphragm. Apparently, additives in the gas attack the neoprene and make it lose its elasticity. The diaphragm goes limp and can't pump like it's supposed to (ouch), so the engine gets starved for fuel. If I recall correctly, the diaphragms were about $15 each. That's a little pricey, so I suggest you look at the ones you've got before you order replacements. Good luck. Peter S/V Raven
I had a similar problem with a Tohatsu 5hp. If your outboard has a mechanical fuel pump (it's mounted on the side of the carb), you might want to check the neoprene diaphragm. Apparently, additives in the gas attack the neoprene and make it lose its elasticity. The diaphragm goes limp and can't pump like it's supposed to (ouch), so the engine gets starved for fuel. If I recall correctly, the diaphragms were about $15 each. That's a little pricey, so I suggest you look at the ones you've got before you order replacements. Good luck. Peter S/V Raven
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R.W.Landau
hose seal
I have seen this problem on other motors. The first thing to check out is the "o" ring in the quick connect on the fuel hose. A small crack, or piece of dirt will affect the fuel moving due to air leak breaking the vacuum in the fuel line. r.w.landau
I have seen this problem on other motors. The first thing to check out is the "o" ring in the quick connect on the fuel hose. A small crack, or piece of dirt will affect the fuel moving due to air leak breaking the vacuum in the fuel line. r.w.landau
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Rick Webb
R. W. Reminded Me (By The Way, Cool Initials)
The fuel fitting on my motor once was hit by the starting handle and cracked I did not notice it untill on my way out of the channel the engine quit. It was not a cheap part and none of the Mercury places around carried it. After replacing it I realized it could have been jury rigged and bypassed and I would not have missed a week of sailing. That is one more place to check.
The fuel fitting on my motor once was hit by the starting handle and cracked I did not notice it untill on my way out of the channel the engine quit. It was not a cheap part and none of the Mercury places around carried it. After replacing it I realized it could have been jury rigged and bypassed and I would not have missed a week of sailing. That is one more place to check.
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John Larsen
Took a class
I took a small engine class last year at the local vo tech. Cost $85 but I learned a lot. Saved me the cost of getting my motor repaired and I'm more confident that I could make temporary repairs on the open water should that ever occur.
I took a small engine class last year at the local vo tech. Cost $85 but I learned a lot. Saved me the cost of getting my motor repaired and I'm more confident that I could make temporary repairs on the open water should that ever occur.
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