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Suzuki df50a

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Ahooo

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Engine reach full rpm if suddenly put throttle handle maximum but automatically it dropping rpm it drop 6000 to 3000,2800 like. And again if suddenly put throttle maximum not increase rpm. After stop and start again it and put throttle suddenly it reaching 6000 but dropping…
New fuel pump
New spark plugs

Any help please?
 
Sounds like your fail safe system is activating, the engine ECM will limit the RPMS to 3000rpms. Do you have a Suzuki tachometer installed? If so it should be generating an error code assuming it’s operational. Could be a sensor acting up, could be a component acting up. You didn’t provide much information. What year is the engine? How many hours on the engine? When was the last time the water pump was serviced? Any error codes?
 
William01 said:
Sounds like your fail safe system is activating, the engine ECM will limit the RPMS to 3000rpms. Do you have a Suzuki tachometer installed? If so it should be generating an error code assuming it’s operational. Could be a sensor acting up, could be a component acting up. You didn’t provide much information. What year is the engine? How many hours on the engine? When was the last time the water pump was serviced? Any error codes?
Click to expand...
Suzuki df2013
Diagnostic tool didn’t show any fault.
Fuel pressure 39psi
After engine start disconnected neutral switch so no safety, it can accelerate 6000 but dropping.
Engine overhaul due to this problem but same.
engine temperature 41c
I have diagnostic tool reading pictures but cannot uploaded
Thank you
 
William01 said:
Sounds like your fail safe system is activating, the engine ECM will limit the RPMS to 3000rpms. Do you have a Suzuki tachometer installed? If so it should be generating an error code assuming it’s operational. Could be a sensor acting up, could be a component acting up. You didn’t provide much information. What year is the engine? How many hours on the engine? When was the last time the water pump was serviced? Any error codes?
Click to expand...
If tps removed then rpm stay 4000
 
A TPS should generate a 2-1 code. Wonder why it didn’t? I don’t think you can replace the TPS separately Suzuki will want to sell you the entire throttle body assembly.
 
To me it sounds like your fail safe system is limiting your rpm to 3000rpms, usually there is an associated code. I have read that some issues will not generate a code, fuel system issues is one of them. If you are having injector issues I would THINK your rpms wouldn’t be limited to 3000 by the ECM they would be whatever the engine can muster. I guess it could be injectors but can’t say for sure. Your fuel pressure is 39psi, from my 2009 DF90A Service Manual fuel pressure should be 36psi, close enough? Your engine temperature is 41C, specs for my engine is 58-62C.
 
Check your “mail” thru this forum. Don’t know if I’ll be able to evaluate the diagnostic report but try sending via this forum.
 
Fuel injected amount 22mcc rpm 3200
If removed tps fuel injected amount increase 25mcc rpm 4000.. I think problem is not increase fuel amount due to some reason
 
I have no idea if thats the correct amount of fuel per injector pulse at that rpm. A Suzuki technician would likely know if those numbers make sense.
With the work done on the engine I’m assuming you have replaced the low and high pressure fuel filters?


Try asking your questions on the above link. There are some very knowledgeable people on that forum that will be more help than me.
 
I checked with my service manual and nowhere does it discuss the amount of fuel per pulse, duration of the pulse. Below is an overview of the fuel system.

IMG_7411.jpeg
 
William01 said:
I have no idea if thats the correct amount of fuel per injector pulse at that rpm. A Suzuki technician would likely know if those numbers make sense.
With the work done on the engine I’m assuming you have replaced the low and high pressure fuel filters?


Try asking your questions on the above link. There are some very knowledgeable people on that forum that will be more help than me.
Click to expand...
I changed throttle body ( taking another engine) but problem not solve… throttle handle put maximum rpm 6000 but automatically decreasing to 2800
 
What troubleshooting have you done? I’d strongly suggest you get a genuine Suzuki service manual. Depending on the age of your engine you might be able to find a pdf online for a decent price.
 
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