P0420 truck not starting:

Did that when it used to sometimes start but no longer starts at all. But it will definitely not start if fuel is not getting to the lines no?

@Dm93 has helped me narrow it down to a possible electrical issue since the fuel pump works but when connected to truck fuel does not reach the lines.

 

If it was fuel, regardless what the pump or lines are doing...
You spray brake cleaner down a port in the intake without removing the air snorkel tube, it will start & run...

We use to drive vehicles with bad fuel pumps to our stalls from the tow drop off area, using a can of brake cleaner...

 

So you have no power to pin 5 of the COPN relay with the key on?

 

No power with key on when reading with the multi meter on the port and the actual pin.

@slater ok I will try that tomorrow thank you

 

Is your EFI fuse (20A) good?

 

Tried the break cleaner trick and it didn’t work but I did have engine suction, so I checked the spark plugs again for spark and there was no spark from any of the plugs (ig that’s what I get for having someone else check for me).
The plugs seemed a bit damp I assume from fuel or break cleaner?
Im going to check all the sensors and maybe force restart the computer.

 

Did you check your EFI fuse?
We need to address the no power to Pin 5 of the COPN Relay because that same power feed also feeds the ECM, if the ECM is offline your not gona have anything so no need to be checking sensors right now.
It comes from the EFI Relay which is fed by the EFI Fuse.

 

Efi fuse was blow and switched out, got spark again and the truck started after gassing it and spraying the break cleaner in it for a minute. Black liquid was spewing from the tail pipe for a while but stopped and the truck starts usually buy the second time trying to crank it.
We drove it and three pending codes popped up:
p0171 (system too lean)
P2195 (indicates an issue with the oxygen sensor signal on Bank 1 Sensor 1, specifically that it's stuck lean)
And P0304: cylinder 4 misfire.

We erased them and drove for about an hour and none came back except P0420:Catalyst System Efficiency Below Threshold (Bank 1)


We checked again for an exhaust leak, found nothing. I’m going to take the 02 sensor off and maybe even clean one of the old ones but don’t know if i should keep driving to see if the computer is still adjusting to new parts or check for exhaust clogs somewhere.

 

So the truck starts, runs, and drives normally now?

If so we still need to look a fuel trims and AFR/O2 sensor data and see if we have an issue or if the cats are just not working anymore.

 

Well, you driving it around with a p0304 & ignoring it, caused a very expensive p0420, but what do I know.....

 

@slater the p0420 has been persistent and was there before and after changing cat converter and can be caused by something up stream right?

@Dm93 im testing the crankshaft position sensor because it can explain the rough idling, trouble starting, and maybe even the slight power drain problem? The camshaft was a little dirty but was working when testing with the multimeter so that just leaves the crankshaft and if that is fine where do you suggest I look next?

 

Found a test online for the crank shaft position sensor:
Resistance Test (engine off):

• Set multimeter to ohms (Ω).
  
  
• Measure between Yellow (signal) and Black (ground).
  
  
• Expect ~950–1250 ohms.
  

AC Voltage Test (engine cranking):

• Set multimeter to AC voltage.
  
  
• Probe Yellow (signal) and Black (ground).
  
  
• Have someone crank the engine.
  
  
• You should read ~0.5 to 1.5V AC or higher.
  
  
  When testing the ohms I got a 1 on my multimedia which I assume means open line meaning that it’s faulty but decided to do the volt test anyways and got a reading of -1. Is this the right way to do this?

 

I highly doubt the cam or crank sensors are your issue with the rough idle, those will nearly always set associated codes.

We already suspect we have an issue with fuel control being we have a P0171, like I said we need to look at fuel trims, MAF, and AFR/O2 sensor data and see whats going on there.

The truck runs and isn't setting a P0335 code so that tells me the crank sensor is most likely good, in any case the signal output can only be effectively checked with an oscilloscope.

 

If the meter is auto ranging a 1 would mean a near short circuit as in 1 ohm an open would be indicated by an OL in the display.

Voltage reading a negative 1 would mean that the leads are reversed.

 

Here is the playback data of a drive.

https://files.fm/u/6efurshure