Truck started stuttering again

[IBMobile]

Was this the injection pump relay or the ASR relay?   I'll try it with my truck and see what the spikes look like, may be swap relays to see if pattern changes. 

 

Test condition:

• Engine cold
• Ignition switch on 
• engine RPM 0
• battery voltage 12.4V  
• Injection pump fuel temperature 84°F

Test guideline:

• FPR (fuel pump relay) out and pins 30 and 87 jumped, ASR (automatic shut down relay) in place.
• FPR in place, ASR pins 30 and 87 jumped.
• FPR out, ASR in.
• FPR in, ASR out. 

Result observed:

• Injection pump voltage constant 12.2V during testing
• ECM voltage constant 12V during testing
• Injection pump shutoff circuit, OFF with random ON spikes
• fault codes 1689 and 1693 induced  
• faults cleared and engine started with no problems.

Conclusion:            

• Both the FPR and ASR have no control over the fuel shutoff circuit between the ECM and injection pump.  

• The ECM is responsible for this OFF/ON condition.  The ECM power is supplied by unswitched fuse #3 in the PDC. 

   

           

Edited June 24, 2020 by IBMobile

[IBMobile]

Testing if relays cause Off/ON spikes in injector pump fuel shutoff circuit 

 

Test condition:

• Engine cold
• Ignition switch on 
• engine RPM 0
• battery voltage 12.4V  
• Injection pump fuel temperature 84°F

Test guideline:

• FPR (fuel pump relay) out and pins 30 and 87 jumped, ASR (automatic shut down relay) in place.
• FPR in place, ASR pins 30 and 87 jumped.
• FPR out, ASR in.
• FPR in, ASR out. 

Result observed:

• Injection pump voltage constant 12.2V during testing
• ECM voltage constant 12V during testing
• Injection pump shutoff circuit, OFF with random ON spikes
• fault codes 1689 and 1693 induced  
• faults cleared and engine started with no problems.

Conclusion:            

• Both the FPR and ASR have no control over the fuel shutoff circuit between the ECM and injection pump.  

• The ECM is responsible for this OFF/ON condition.  The ECM power is supplied by unswitched fuse #3 in the PDC.