Repairs Scag TT engine running problems. Need suggestions please.

deamer1

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  • / Scag TT engine running problems. Need suggestions please.
I have a SCAG TT with a 27hp Kawasaki Engine.
Problem is that it will not continue to run after starting.
I was mowing for a hour or so, shut the engine off for a few minutes. Attempted to restart it and it started, but shut down within 30 seconds. Upon multiple attempts to start, it continued to do the same thing. The cranking was normal, the engine started and ran to the throttle setting, then the rpm's decreased rapidly and the engine quit. Multiple attempts to start using more/less choke and more/less throttle. Nothing helped, the engine continued to do the same.
I have went through much trouble shooting and came up with nothing definite as to the cause.
Checked battery (good), checked plugs and spark (cleaned plugs, spark good), measured fuel pump output (correct per the specs), Fuel filter (clean),
Fuel level (half tank), fuel shutoff (open ) Tested Carb fuel shutoff relay (tested via tech support method, tested good)Throttle linkage and choke linkage operating normal with the controls. tested seat switch (good), Cleaned carburetor (No changes, run same) clean air filters (no change) Poured low amount of fuel into carburetor and it ran for a longer time, but then quit running upon the fuel being used up.
The engine will start each time using normal starting procedures, but will only run for a very short time, (30 seconds max.)
Wondering about the Carb primary jet being dirty, but have no experience with the jets and don't want to create additional problems messing with it. Wouldn't know what to attempt with the jets.

I'm running out of ideas. Would love to have any and all ideas/experiences with this problem.

I appreciate any and all input.
Deamer1
 

Luffydog

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  • / Scag TT engine running problems. Need suggestions please.
You can’t deliver fuel if it’s not there when needed is what I am thinking. Take the fuel line after the shut turn it off and disconnect. Take fuel cap off with a bright light look down inside the tank. There should be a orange plug there look and see if it is clogged up. Blow air back Thur the line into the tank with cap off and shut off open this will allow all debris to be blow out but down fall is it is in your tank. After cleaning the line and plug run tank dry as possible then take something to suck the tank clean of all the grass clippings. Or if you have a small tank hook directly to the carb and see if it runs normal without the shut down. If it doesn’t you have another issue. Is this engine dfi? If so it might be a fuel regulator. I would think the line is blocked and not getting the fuel delivery when needed. Seen it many times on these. Check the fuel flow before you blow it back then check it after it bet you see a big difference in the flow. It should be the same flow as your hose dia. Nothing smaller. Double check that and let us know what you find.
 

mcdonell

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  • / Scag TT engine running problems. Need suggestions please.
Just trying to add to the conversation what I would do, but Luffydog is already giving top notch advice.

Sounds like a fuel delivery problem. Some fuel is getting through but not enough all the time especially when it is running. When the motor dies, I would immediately pull off fuel lines and check to see if fuel supply is sufficient. I bet it aint. I would also change the undependable $10 fuel pump and filter, then carefully inspect the fuel pump vacuum hose for leaks.

It sounds like your saying the motor will crank and start every time. But it will just not run very long. Can you get the motor to run a little longer by applying the choke and by shutting down the mower blades. That would help confirm the fuel issue. If the mower starts easily and mows fine for ten minutes, I would not mess with the jets.
 

deamer1

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  • / Scag TT engine running problems. Need suggestions please.
Mcdonell,

Thanks for the input for my mower problem.
This starting problem is happening with the blades disengaged. I have attempted to use the choke to keep the engine running, but it has no effect. It always dies. Presently looking into your reply and the other also.
I do appreciate your input and will respond with any results upon completion.
Deamer1
 

ILENGINE

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  • / Scag TT engine running problems. Need suggestions please.
Deamer1 I sent you a PM, I have an idea what the issue is but is complicated to explain what you need to look for in words.
 

deamer1

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  • / Scag TT engine running problems. Need suggestions please.
This is Deamer1 and I want to give a huge "Thank You" to Luffydog, Mcdonell and ILENGINE for the good input to my problem with the Scaq Mower.
Each of your suggestions helped me to finally get the machine running like a new one.

Some update on the machine: I dismantled the machine and pulled the carburetor three different times.
While working on the engine/carburetor I also did a lot of testing and cleaning connectors, grounds etc. etc. etc.
The carburetor really boggled me for some time. I cleaned, soaked, sprayed and tinkered with it for a long time. Spent lot's of time studying the carb in the Mikuni manual. Called mikuni about the proper testing of the fuel shutoff solenoid, found out I was correct in my testing, it was good. They then referred me to a mikuni carb. dealer, that they did not provide further tech support to the public, only Mikuni carb dealers.

I made a replacement fuel supply from a plastic bottle, hoses, extra fuel filter and hooked it up to replace the original fuel supply. Symptoms were the same. It ran for a very short time and quit. Dismantled the carb. and checked the main jets, pilot jets, air passages, pulled the float and checked the installation, it seemed correct. Finally I took a multistrand cable apart and used one of the wires to go into the fuel bowl seat bottom. I was careful with it and ran it completely through the seat up and out of the top of the carburetor. I did this several times. Then I reassembled the entire machine and checked for gas coming from the fuel pump into the carburetor and into the fuel bowl. I had fuel reaching the fuel bowl!
Set the throttle to full, set the choke to full, turned the key to start and it started instantly! What a relief that was!

I spent a lot of time working on this problem, but it was worth it. I learned a lot about fuel/air mixtures and carburetors.
Again a special "Thank you" to everyone that offered advice, it all helped.
 
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