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I've been having this problem recently. Most of the time when I got out on the big lake. I can get out just fine engine runs great. Coming back after a 4-5 salmon troll at 600-800 rpm. Coming back at 2500-3000 rpm. I will just be able to get it up on plan. Then she sputters and starts to miss and will die if I'm not fast enough to throttle her down. I've put new points, condenser, plugs, plug wires, carb has been rebuilt. I don't know what it could be. Maybe fuel related. Haven't checked. But looking for opinions. Thanks in advance.

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We just had a boat act like that and it was fuel related. Port engine would cut out at 3500rpm. We rebuilt the carb and it helped the problem. We also routed a second vent so both tanks are vented properly also helped but not solved yet. Finally ended up being the check valve coming out of the tank was getting plugged with debri. We took the check valve out and now it runs great and holds 4000rmps.

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check your fuel filters, at higher rpms you are going through a lot more fuel than at low rpms. I have seen the same the same thing you are talking about several times and almost always its dirty filters. if you have a oil like type filter cut it open with a hack saw and you will be surprised how black they are, i have done that with many car filters and the same thing black inside.

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I second the filters. Not an expert, but I've heard a lot of people nowadays complaining about fuel with the new ethanol regs and such.

Luckily I've had good times running premium through my 125 2 stroke

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I'll third filters...try running Seafoam through it and see if that helps. Also, check your fuel line. I just had this same problem and found out my fuel line was rotted out and starving the engine of fuel.

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I also say filters then put seafoam in ur tank cleans everything out and works great. It worked on my big boat and 90 horse 2-stroke merc

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Where do you fish out of? I answered your other post as well. Put a volt meter on the coil check the voltage drop across the coil and the voltage to the points. My bet is it runs great when cold and trolls fine just will not run fast after getting warm.

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Run pure gas no ethanol that helped me I had the same problem with mine this season. But what really fixed it was a timing adjustment at the sport center now it runs the best it ever has since I've owned it, plus check your plug gap, the gap is almost never true out of the box, and that makes a difference on marine motors. And what type of motor is it? ?

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I have had the same issue a couple of times. Check the anti siphon check valve in your fuel line. On my Sea Ray its in the fuel supply line near the top of the gas tank. The small spring operated ball check valve had crud trapped in it and would not allow enough gas to pass through. It would idle fine all day but wouldn't run at higher RPM. I removed the check valve and blew the crud out with an air hose, problem solved. The crud looked like bug parts, likely from using a 5 gal can that sat in the garage all winter.

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I've had gas problems this last month, getting algae like crude in the fuel filter...seafoam seafoam seafoam, did not use it this summer and I think that is why I had the problem. Pumped the gas out and filtered it and solved the problem. Also keep your tank full between uses to help reduce condensation when it's so humid with extreme temp changes. I had a check valve problem a couple years ago that caused similar problems and solved that by repositioning it so it was facing in the up position so gravity could assist the check ball, won't fall in place if it's facing down. My first look would be bad gas and or the filter though.

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I'm having the same problem. No anti siphon valve near my gas tank though. Have changed fuel filter/water separator's 3 times. Changed coil. Changed cap, contacts, confenser, plugs, wires. Switched carbs between both engines. Same engine still gives me ****. Under power no problem until 3000 rpm then fouls out unless I can throw it into neutral. If/when I get mine figured out, I'll post the resolution.e

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I'm having the same problem. No anti siphon valve near my gas tank though. Have changed fuel filter/water separator's 3 times. Changed coil. Changed cap, contacts, confenser, plugs, wires. Switched carbs between both engines. Same engine still gives me ****. Under power no problem until 3000 rpm then fouls out unless I can throw it into neutral. If/when I get mine figured out, I'll post the resolution.e

I got a new ballast resistor. Gunna try it tomorrow. See if that fixed it.

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we had the same problem, new coil, points, condensor cap and rotor, we also put in new plugs. Still have to test it out. Our boat runs good on the way out, trolls good but on the way in it wont go over ten mph. SPudders and runs rough. Ours is a 351 for. 1977 century raven.

I will let you know if i turns out. Or pm me. Havnt been able to go cuz of wind.

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If all the above recommendations don't work make sure you don't have water in your gas it doesn't take much.

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If all the above recommendations don't work make sure you don't have water in your gas it doesn't take much.

It's not water when you're running 2 engines off the same tank and one engine is fine while the other can't get over 3k rpm

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Check voltage at the coil on the points side should be under 10vdc at idle some will only run about 6v at idle. As you increase rpm the voltage should rise slightly but you should never have full voltage at the points. So every 12v points system either uses a resister coil or a ballast resister to trim voltage to the points. Some boats came with a resister coil and the coil got swapped for a non resister one by mistake. Mine came with a resister coil but the ballast resister was bypassed so we had to have a ballast resister added to fix the issue. Hall's in Muskegon was never able to figure this out and the result is I have hundreds of dollars in new parts I likely never needed because they could not see the problem.

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Check voltage at the coil on the points side should be under 10vdc at idle some will only run about 6v at idle. As you increase rpm the voltage should rise slightly but you should never have full voltage at the points. So every 12v points system either uses a resister coil or a ballast resister to trim voltage to the points. Some boats came with a resister coil and the coil got swapped for a non resister one by mistake. Mine came with a resister coil but the ballast resister was bypassed so we had to have a ballast resister added to fix the issue. Hall's in Muskegon was never able to figure this out and the result is I have hundreds of dollars in new parts I likely never needed because they could not see the problem.

Would this happen all of the sudden? Boat ran fine first 2 years I've had it? No resistors on either engine. Port runs fine, starboard has the issues

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It could you also have a 12v non resister wire coming from the starter that gives full voltage when starting. I have seen them stay hot all the time if the starter solenoid goes bad or has been under water in the bilge. If the voltage at the points is too high the coil will get extremely hot and begin to break down. The last time my boat failed the coil was so hot you could cook with it. we actually pulled the coil and laid it on a bag of ice on top of the motor and was able to run in with it.

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It could you also have a 12v non resister wire coming from the starter that gives full voltage when starting. I have seen them stay hot all the time if the starter solenoid goes bad or has been under water in the bilge. If the voltage at the points is too high the coil will get extremely hot and begin to break down. The last time my boat failed the coil was so hot you could cook with it. we actually pulled the coil and laid it on a bag of ice on top of the motor and was able to run in with it.

Wow, interesting. I guess ill.install a resistor and hope.for the best. Thx

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