2002 df40 wandering rpms at 3000rpm

[iisinc]

I am working on a 2002 DF40 EFI. when the throttle is raised to 3000rpm, in nuetral, then the engine RPMs fluctuate from about 2800 to 3200. Below this setting and it seems to smooth out. To me is seems like it could be a fuel pressure problem. No codes are present. Does not seem to be an electrical problem. Has anyone seen a fuel pressure regulation problem like this. Any suggestions from the experts would be deeply appreciated. Thanks, I will be watching for a reply.

 

[clanton]

Re: 2002 df40 wandering rpms at 3000rpm

It is suppose to do that.

 

[iisinc]

Re: 2002 df40 wandering rpms at 3000rpm

I've been working on engines (carbs,EFI's, DFI's etc...) for quite some time and have never come accross this in normal operation. Could you elaborate on your answer. To clarify, the engine fluctuates rapidly from about 2800 to 3200 rpm over and over again. Thanks again.

 

[clanton]

Re: 2002 df40 wandering rpms at 3000rpm

The ecm is programed to not allow the engine to turn over app 3000 rpms in neutral, to turn over 3000 rpm must be in farward or reverse gear. You can find this information in the service manual section 2 or 3. The neutral switch is the control that turns the ecm on or off, for this function.

 

[iisinc]

Re: 2002 df40 wandering rpms at 3000rpm

Thank you very much. I learn at least one new thing everyday. Once again, thank you.

 

[clanton]

Re: 2002 df40 wandering rpms at 3000rpm

If you have a no code driveable problem these injected 4 stroke engines, check the fuel filter between the pump and injectors. If the inside of the hose nipple is rusted and trash comes out of the bottom nipple of the vapor seperator most likely will have to come off and be cleaned, check fuel pressure regulator.