{youtube}CEjmo_qT4yQ|615|345|0{/youtube}

This vehicle has an intermittent misfire that we are trying to locate. Here we will be focusing on the injectors, making sure they do not have any flow problems (restrictions or leaks) An external timer tool will be used to fire the injectors at exact intervals while watching fuel pressure drops on a pressure gauge. Since we cannot get to the injector connectors directly, we will be using a main bulk connector to access the injector control wires. This same procedure can be applied to many different systems.

Engine Performance Diagnostics chapter 16 pages 9-16

symptoms 50

  • fuel pump fuse keeps blowing
  • intermittent no start
  • fuel pump relay buzzes
  • when heater is turned on the fuel pump relay fuse blows

fix 50

  • repair loose main block ground

test shown enh 50

  • fuel pump current measurement using a low amp probe and scope
  • GM fuel pump relay diagram breakdown
  • fuel pressure test
  • fuel pump relay control circuit test
  • fuel pump relay ground test
  • fuel pump relay load side test

Tools used

  • lab scope
  • low amp probe
  • wire piercing probe
  • jumper wires
  • back-probing pins

end faq

{accordionfaq faqid=accordion15 faqclass="dotluvfaq help2 aligncenter headerbackground headerborder contentbackground contentborder round7" active=item0}

Playlist

(Chapters 14, 15,16) Fuel Delivery and Fuel Pressure Testing

Related videos:

Low Fuel Pressure from a bad fuel pump ground (Ford Ranger):

{youtube}rQ7tvIxQSt0|615|345|0{/youtube}

Poor running, flashing CEL, no codes (bad computer ground) Toyota:

{youtube}44dP6X3QS5A|615|345|0{/youtube}

Fuel pump electrical circuit diagnosis (no fuel pressure testing) GM:

{youtube}ZgNY3ZpjSsU|615|345|0{/youtube}

How to test an electric fuel pump (no fuel psi testing) Ford:

{youtube}F2ZXhai-x9k|615|345|0{/youtube}

How to identify a bad main relay on a Honda (PGM-FI):

{youtube}6CMZ4g8n0FQ|615|345|0{/youtube}

end faq

{accordionfaq faqid=accordion3 faqclass="darkhivefaq defaulticon headerbackground headerborder contentbackground contentborder round5" active=item0}


For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available as an eBook or paper book.

Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium. There is a 14 day free trial.

On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!