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Engine problems 90 hp johnson 2 stroke

J

Jmeyer73

Member
I hope someone can help me. I have a 2000 90hp Johnson 2 stroke, The guy I bought the motor from said he took off the carburetors and cleaned them then put them back together, The issues im having is when you run above 3700 RPM’s to me it fills like it’s not getting the gas like it should. The motor will surge up and down almost like a fouled out plug. I put new plugs, new primer ball, new filter and still the same thing. IF i stay under 3500 RPM’s it runs like a champ im not sure on the gas milage this older motor is suppose to get but I went 35 miles and only burned 10.5 gallons of gas with 3 people and all our fishing gear. Any help to point me in the right direction would be greatly appreciated thank you.
 
Perhaps run with a timing light and observe the flashing of the light on each lead.-----Checked for water in the fuel ?----Oil injection in service and working properly ?----What happens if an assistant operates the manual fuel pump ?-----What happens when you test with a seperate / different fuel tank and hose.
 
Surging and that nice fuel economy indicates fuel starvation. Check to see that the main jet in bottom of float bowls is completely open and cleaned to correct size. Many will look open and take air and carb cleaner through them, but in reality are lined with a thin film, restricting flow. I use a welding tip cleaner and CRC brand throttle body cleaner. Careful with the stuff.....don't get it on your hands or even on plastic....it's strong.
 
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Thats what im thinking its the carburetors. Maybe he didn’t set the floats or like you said he didn’t clean them out all the way. Could the fuel pump be going out ?
 
racerone said:
Perhaps run with a timing light and observe the flashing of the light on each lead.-----Checked for water in the fuel ?----Oil injection in service and working properly ?----What happens if an assistant operates the manual fuel pump ?-----What happens when you test with a seperate / different fuel tank and hose.
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It has all fresh gas with new line and primer ball, fuel filter clean also, guy took off the oil injection so I have to mix gas & oil 50:1
 
timguy said:
Surging and that nice fuel economy indicates fuel starvation. Check to see that the main jet in bottom of float bowls is completely open and cleaned to correct size. Many will look open and take air and carb cleaner through them, but in reality are lined with a thin film, restricting flow. I use a welding tip cleaner and CRC brand throttle body cleaner. Careful with the stuff.....don't get it on your hands or even on plastic....it's strong.


Thats what im thinking its the carburetors. Maybe he didn’t set the floats or like you said he didn’t clean them out all the way. Could the fuel pump be going out ? Should I do that on all 4 carburetors?
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I know this is an old thread, just thought I'd post it to possibly help someone searching. The problem could be the vro fuel pump if you have one. The seals go bad and stop pumping exactly like they should. eventually it will get so bad you can't start or start getting a lot of oil being pumped. Your exhaust will be thick all the time. And beware, there aren't any oem rebuild kits available anymore. All that's out there is very cheap import stuff. Some people complain that they only last an hour or so before going bad. They're very hit or miss. I'd buy 2 from 2 separate vendors just to make sure. The imports aren't expensive.
 
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