Hey everyone new member here,

I bought a 94 s10 Blazer a little over a year ago and love the truck. Besides doing my usual tuneup stuff like plugs and wires and oil changes it didn't need anything for awhile. Last winter it had a hard time starting so I ended up changing the fuel pump which fixed it. Truck has around 150k and hasn't needed much done to it at all. I started having issues with highway driving where it was hard to keep it at speed. I ended up replacing the spider injector unit and fuel inlet lines as well. A month or so ago the truck became increasingly harder to get up any kind of hill and power had decreased. My first suspicion was a plugged cat and the exhaust looked pretty rough. Upon further inspection I found that my exhaust manifolds has cracks as well. Fast forward and I have replaced the whole exhaust from new manifolds all the way back to the tailpipe including the O2 sensor in the y-pipe. After all this I still cannot get this truck running right and it has only gotten worse. Now it seems like after it has warmed up it just flat out loses all power and I am literally crawling up hills. It also seems to want to die on me if I give it gas from a dead stop.

I have replaced:

1. Whole exhaust including manifolds, y-pipe and o2 sensor, new cat and muffler and piping.
2. fuel pump and filter as well as spider injector unit and fuel return lines.
3. TPS sensor
4. Knock sensor
5. EGR valve
6. Coolant temp sensor
7. Plugs, wires, distributor cap and rotor, and ignition coil.
8. Have replaced and checked vacuum lines

I may be missing some stuff as well but I am at the point of giving up myself. My next steps will be to change the plugs again and check fuel pressure. The truck doesn't have any engine light as well. Other thoughts I have had may be the crack position sensor or the actual computer/ecm in the truck but I figured those would at least throw me a code.

Any ideas or thoughts out there? thanks.

 

Checking fuel pressure is good. Also check engine at night for sparks on your wires. I found two on my vehicle that were jumping to ground at different times. I had ac wires with not very many miles on them. You also mentioned the miles at 150,000. You might have a timing chain issue of stretch that allows the timing to be a bit off which will decrease power.

 

While checking on the plugs again it might be worth doing a compression test and if possible and all the plugs are out a leak down on the cylinders as well.
Just to do complete diagnostics and might not even be too expensive or hard to do.

 

Not sure if you're still having issues, but did you do both knock sensors? The one on the back of the engine is tricky. Also, there is an ignition module in the distributor. I had to replace that one mine.

I haven't had your same exact issues, but on the 88 C1500 I used to have I went through a couple fuel pumps and several filters before I realized the fuel tank was full of rust. Ended up installing a brand new tank, along with pump and filter to fix the issues I was having with it. Perhaps your fuel tank is the same way.

One other stupid thing I did on my 1500 was getting the firing order wrong when doing new cap, rotor, and plug wires. . . I was sure I had it right but I didn't. It didn't run horribly, but was way down on power. Once I figured it out and got the wires on correctly it ran great. Might double check your firing order as well.

 

I have got the truck running good again. I ended up replacing the whole distributor and finally the MAP sensor. I also took off all the sensors, like the EGR and IAC, and cleaned all intake ports and throttle body again. I suspected I may have had a battery on its way out so switched to a different one. Still getting a bit of surging at startup but the truck will hold and idle good now. Going to run some fuel cleaner through it next tank to smooth out the rest but its got all its power back and no check engine lights.

 

Glad to hear you got it mostly sorted out, and got all the power back. I'm jealous of no CEL lol. I need to take my intake apart and fully clean everything too. . . Can't seem to get rid of my EGR code.

 

If it makes you feel any better my ABS light is on lol Just want to get through winter so I can start my suspension upgrades in the spring!

 

Aw man. . .lol. . stupid idiot lights. They can never all be off for long. . . Pretty sure I've fought them on every car I've ever owned.