1985 Suzuki 4 hp

[bcguy]

1985 4 hp 2 stroke engine: Will not start except at near full throttle. Once there if you try to slow down the engine quits. Anyone have a similar problem with an older 2 stroke. I will be doing the usual thing like clean out carb, change the fuel ...all the typical stuff. If the problem is still there I am defaulting to the fuel pump diaphragm unless there is something I might be missing.. thanks

[liquidice]

Originally Posted by bcguy

1985 4 hp 2 stroke engine: Will not start except at near full throttle. Once there if you try to slow down the engine quits. Anyone have a similar problem with an older 2 stroke. I will be doing the usual thing like clean out carb, change the fuel ...all the typical stuff. If the problem is still there I am defaulting to the fuel pump diaphragm unless there is something I might be missing.. thanks

Low speed jet clogged. Carb clean for the win. I like to spray a little carb cleaner, then cover the choke intake with the meat of my palm , put the throttle low (so it doesn’t start) and pull the starter rope a few times. Sometimes you can suck the fuel through without disassembling the carb. It has worked for me many times.

[NoTies]

Originally Posted by liquidice

Low speed jet clogged. Carb clean for the win. I like to spray a little carb cleaner, then cover the choke intake with the meat of my palm , put the throttle low (so it doesn’t start) and pull the starter rope a few times. Sometimes you can suck the fuel through without disassembling the carb. It has worked for me many times.

Or choke it at high revs a few times. Often does the same thing.

[Lake-Effect]

Originally Posted by bcguy

1985 4 hp 2 stroke engine: Will not start except at near full throttle. Once there if you try to slow down the engine quits. Anyone have a similar problem with an older 2 stroke. I will be doing the usual thing like clean out carb, change the fuel ...all the typical stuff. If the problem is still there I am defaulting to the fuel pump diaphragm unless there is something I might be missing.. thanks

Owner of a 1983 Suzuki 5 HP 2-stroke. It runs really well, but I'm fairly religious about using fresh ethanol-free gas with gas stabilizer or SeaFoam. I also like to squirt carb-cleaner down the throat while the engine's running - once or twice a year.


So my first recommendation would be to focus on the carb.

[BruceS]

If that doesn't help then suspect the seal under the flywheel.
Being a vertical crank sometimes the upper seal get's a lot less lubricating, especially on low revs & short runs. Eventually that bearing also will 'rumble in the jungle'.

[alansmith]

some great advice there gentleman...i'll have to put those in my bag of tricks. I inherited a 4 hp 2 stroke Johnson. It had similar problems so i rebuilt the carb, fuel pump, new hoses....etc...

[liquidice]

Originally Posted by bcguy

1985 4 hp 2 stroke engine: Will not start except at near full throttle. Once there if you try to slow down the engine quits. Anyone have a similar problem with an older 2 stroke. I will be doing the usual thing like clean out carb, change the fuel ...all the typical stuff. If the problem is still there I am defaulting to the fuel pump diaphragm unless there is something I might be missing.. thanks

What’s the choke situation? Are you starting with the choke pulled on? What about after you warm up? If a 2 stroke motor can be started and run, in my experience, it’s performance issues can be improved by twiddling with the throttle and choke, with a fresh tank of carefully oiled gas. Start it, bring the throttle down until it it almost dies, and then try to “save “ it by slowly pulling on the choke. Repeat this, slowly stepping the throttle down just to try to get some fresh gas flowing through the jets. Sometimes it can save you a carb clean.