I got me a Tahoe!

[j91z28d1]

I've already hit my first head scratcher. How am I missing the fuel pump relay but the vehicle fires up fine?

it's a common head scratcher. the newer ones have a fuel pump module under the truck that runs the pump. the older ones had a relay.

pull the fuse.

 

[Nutro]

Ok so there is no fuse there haha. What the heck

 

[j91z28d1]

my software shows fuse 56 ecm-ign fuse sends power to the ecm and the fuel pump module.

you can also unplug the injectors if it's easier.

 

[Nutro]

So cyl 4 has around 170psi

 

[Nutro]

So I check compression on number two as well and it was right at about 168 also. I pulled the valve cover and had my dad spin it over and all of the rocker arms are moving like they should. Even number four that has a cylinder misfire the intake and exhaust Rockers are both moving up and down as it Cycles through the start. I don't see any evidence of a broken valve spring or at least I don't see any cracks

 

[OR VietVet]

You have no compression problem on those cylinders. Problem is elsewhere.

 

[mountie]

You have no compression problem on those cylinders. Problem is elsewhere.

What about replacing the #4 coil & wire??

 

[OR VietVet]

What about replacing the #4 coil & wire??

In post #1 he said he tried that.

 

[OR VietVet]

I never asked. Can you see/feel a misfire at idle? Can you feel a misfire when driving? What exactly was the code or is the code? P0304?