Hi all,

With the help of a friend I did a little redneck body work on my '94 Blazer (W) and I'm going to run it to Eastern Washington this weekend. Now that I'm driving it again I've noticed just how sluggish it is. Since the accident in February I've been driving my '93 Sonoma or my wife's '93 Jimmy. The Sonoma, Jimmy and Blazer all have the same drive train: 4.3 Vortec and 4L60E. The Sonoma, being a lighter vehicle, is faster and more powerful than either the Jimmy or Blazer. The Jimmy, however, is also much faster and more powerful than the nearly-identical Blazer.

When I take the Blazer out on the highway it doesn't like to accelerate very quickly. When I mash the pedal the engine waits about two seconds before it starts to increase in RPMs and then it will wind up slowly and gain some speed. It has to shift up and down repeatedly to get up a long hill at about 50mph. The engine seems like it's straining and really working hard to move the Blazer.

I checked the compression and all cylinders are at 110. The #1 spark plug had a carbon trail on the side of the insulator and some other indications of poor running so I replaced it with another AC-Delco. I gave the Blazer a complete tune-up last fall with all genuine AC-Delco parts from Sunset Chev in Sumner. The oil level is normal and doesn't look milky or show any signs of coolant contamination. The transmission fluid is nice and pink and at the correct level. The exhaust doesn't smell bad and there's no other indication of a bad catalytic converter. I replaced the spider and nut kit in January just before the emissions inspection which it passed.

I'm stumped on this one. What should I check next? I'm going to take the Blazer to Eastern Washington even if I have to push it over Snoqualmie Pass because it can carry three accordions and a tuxedo plus everything else I need while I'm away.

As always I appreciate your suggestions!

 

Hey everybody—I drove the Blazer to Wenatchee and then back home. It barely made it over the mountains. It was *VERY* difficult driving it over the mountains because of the lack of power. I've parked it for now while I get my van ready to go to Montana later this week. However, I'm hoping to get to work on the Blazer in a couple weeks when I get back from road gigs.

Currently I'm wondering if there's excess exhaust back pressure. Anybody have any other ideas or suggestions?

 

Typically extra exhaust pressure (from something like a clogged cat) will make the exhaust red hot when you run it up a hill. Keep in mind that other things can do this too (like running lean), but run it up a hill and then try to look at the cat when you reach the top. If it's bright red, this may be the source of your problem.

Otherwise, it could be things like:

Poor Spark
Low Fuel Pressure
No Timing Advance (Timing Wire Disconnected or Broken)
EGR Valve Stuck

to name a few....

 

possible vaccum leak somewhere??

 

Thanks Cadaver666; those are some good suggestions. I've already checked vacuum and there are no leaks. I also know that fuel pressure is good. I replaced the spider and nut kit in January and did the requisite fuel pressure tests as a part of the diagnostic process and it's holding steady at 60psi.

I hadn't considered timing advance. I'll be sure and check that out!

 

Sounds good. You should be able to just set a timing light up and look for the marks. If the timing is right, you have no advance. If the timing is wrong... then your advance is working like it should (sounds like a funny way to test, but if its not advancing then it should be at factory spec all the time).

 

Hey all– just thought I would post a follow-up to this thread. I got busy with various other projects over the summer including getting a new roof on my garage. With that done I took a moment to go back to my '94 Blazer and check things out. The timing was good; it was advanced properly with the wire hooked up and at 0 with the wire disconnected. After swapping the fan clutch out on my '93 Jimmy and getting a noticeable increase in performance I decided to do the same to the '94 Blazer and BINGO! With a different fan clutch it had all the power it used to and ran a lot quieter at high speeds. With that problem solved I can go back to rebuilding the front end of my '98 Jimmy and doing some transmission work on it to get it ready for the winter.

Thanks everyone for your help!

 

So Toby did you put a direct drive fan blade on it or just replace the clutch and fan?I wanted to do this on my 96 but as far as I know the autopart stores near me dont carry the adapter for a direct drive for 96 vortec.

 

What I did for testing purposes was to take the fan clutch I removed from my '93 Jimmy and put it on the '94 Blazer. Back in July I replace the water pump and fan clutch on the Jimmy. The new Hayden clutch I installed had seized up so I returned it to O'Reilly's for a warranty exchange. I had saved the original clutch I removed and I put that one on the Blazer for testing purposes. I wouldn't run the Blazer long-term with that clutch on it because it's a little wobbly. For testing purposes, though, it gave me the answer I was looking for.

If I were you I wouldn't put a direct-drive fan on your rig. The fan clutch is an important part of the cooling system. It kicks in only when it's needed which reduces engine load: a lesson I learned in reverse.