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2006 4.3 mpi issue

M

mark123

Member
Will start cold but idles low and rough
Won't start warm unless give throttle
Runs perfect up to 3600 then intermittent bog above
Fuel pressure only 30 at idle 28 at higher rpm
Spark plugs covered in carbon
Changed IAC, iac filter, new cap rotor button. No improvement. Stalls sometime when brought back to idle.
I'm assuming need new fuel pump and regulator. But couldn't that cause sparks to get carboned up (not wet) I'd assume low fuel pressure would cause lean if anything. Coil looks a bit rusty and slightly swollen, could that cause weak spark? Is it the same coil as on early 2000s 4.3 trucks. Thanks
 
mark123 said:
Fuel pressure only 30 at idle 28 at higher rpm
Spark plugs covered in carbon
Changed IAC, iac filter, new cap rotor button. No improvement. Stalls sometime when brought back to idle.
I'm assuming need new fuel pump and regulator. But couldn't that cause sparks to get carboned up (not wet) I'd assume low fuel pressure would cause lean if anything. Coil looks a bit rusty and slightly swollen, could that cause weak spark? Is it the same coil as on early 2000s 4.3 trucks. Thanks
Click to expand...
There is most likely more than a fuel pump or Reg issue, but need the pressure to spec in order to determine what other issues there might be.

Could be some of the parts you changed are causing more issues, need to test first to determine what the problem is

What is your serial number?
 
Thanks
Motor needs to be scanned for codes and look at the numbers to see where issues are

Until then, measure voltages of TMAP and TPS note their changes as throttle is increased

Look at the shift plate and see if the in-gear switch is adjusted correctly. Disconnect it and measure ohms and see if it changes closed (zero ohms) to open. Also with drive in gear giggle switch contact it some to see if it has intermittent contact

If you have an Alpha drive also check adjustment of interrupter

Gear and Shift Switches.jpg
 
Bt Doctur said:
if its a laminated coil where the lamination's are showing rust , replace it
Click to expand...

AllDodge said:
Thanks
Motor needs to be scanned for codes and look at the numbers to see where issues are

Until then, measure voltages of TMAP and TPS note their changes as throttle is increased

Look at the shift plate and see if the in-gear switch is adjusted correctly. Disconnect it and measure ohms and see if it changes closed (zero ohms) to open. Also with drive in gear giggle switch contact it some to see if it has intermittent contact

If you have an Alpha drive also check adjustment of interrupter

View attachment 35730
Click to expand...
 
There was a code 75 something about fuel level circuit high? No misfire codes etc...
Steel lamination of coil are rusty and outter ones are seperating
 
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