i just bought this 95 blazer 165k off my cuisin and it runs rough he gave up on it. with code 300 on it, fuel injector, plugs, wires, intake gskt, all replaced. egr is not clogged, no unusual carbon build up. it seems to be fine but has anybody have any idea why it missfires? i hear the fuel pump running. it starts after the 2nd 3rd try. bought for 500 bucks im willing to throw 1k to make it run fine.

 

When the CPI spider was replaced, were the internal fuel lines (called the nut kit) also replaced? If not, mostlikely you still have a fuel leak internal to the intake. This will cause random misfires.

You can check for a leak by testing the fuel pressure leak down. If you see the pressure drop after the pump has shut off, then there is a leak in the system somewhere. Barring an actual leak in the fuel pump check valve and no external leaks, it has to be in the intake somewhere.

 

ive taken the upper plenuem out it did smell like fuel and no, the internal fuel lineswerent replaced, they look old.i cant see why i couldnt change them, im going to try that, but im really starting to think its at internal problem bent valve or broken springs.

 

I had to replace those when i had other blazer. make sure u if change them u put in the same kinda of hose in or better. or u will have problems.

 

Hey Kyle,
What is the nut kit?

 

CPI Line Kit - typically referred to as the 'nut kit'.

They are the internal fuel lines running from the outside of the lower intake on the CPI motor to the CPI spider inside the plenum.

 

Ok, thanks.
While talking to the dealer about my missfire issues one of the parts guys mentioned they sell alot of Nut kits for the blazers. I thought that was strange since my nut kit seems to be nothing more then two fuel lines bolted to the gas tank on one end and bolted to the spider assembly ont eh engine side. As far as I can tell they are just plain old fuel line, nothing fancy other then the shape and flares. I am having trouble visioning htem being faulty. Maybe if they had jets or moveable parts in them, yea, but mine seem like empty tubes.

 

well ive finally got aroundto install the nut kit and it still runs rough code 300 still present as well as the knock sensor code. what kind of dist. cap does this blazer take vin code w? hor. or vertical? im lost to what the problem is