My 98 Blazer LT has 180k miles.
Fresh: plugs, wires, cap, rotor, fuel filter.
All vacuum lines replaced last year (dry-rotted: looked like a wild animal chewed them all up)

It starts up instantly, runs great at WOT.

Under light acceleration though I feel a pulsing when taking off from a stop.

Any ideas where to go next ?

Thanks.

 

Sure plenty of ideas. Start with a fuel pressure leak down.
The instructions are all over the board.
If all that passes then IMO it's time to look electrical.


If your willing to take the time you can fix it.


By the way everyone here will help till you get it straight, just don't get frustrated.

 

Fuel pressure seems fine to me.
Turn key on without starting and I get 61-62.
I let it sit for 10 minutes off and it went to maybe 58.
At idle it flickers between 52-54.
Rev it up a little and it stays steady on 52.
Sudden blip of the throttle sends it never higher than 64.


I also checked the PCV while I was there. It was fairly clean and rattled; and when running you can hear it "buzzing" as it should.


Today we drove a little further away than my normal daily commute. Once it was COMPLETELY warmed up I never noticed any issues at all.
Did seem a little chuggy when cold.


I originally wondered if I had water in the gas due to our crazy weather changes; but I've put 2 bottles of Heat through it over the last 3-4 tanks of gas. (my wifes car had starting troubles a few different times and the Heat fixed it every time this winter)


Whats next ?

 

Fuel pressure #'s are a bit hincky.
Do you know how to take the plenum off, it's 10mm deep socket bolts. If you see shiny clean spots you have a leak. If you decide to take it off snag some pic.s and post them.

 

What are you referring to as "plenum" the intake off the top of the motor ?


From what I read on a "how-to" those numbers seemed good.

 

Did some more digging on google. I see you are referring to the top half of the intake plenum.
Are you referring to a "fuel" leak, or a coolant leak in the plenum ?


I'm pretty sure that my intake has been off before.
1- I have 180k on the clock with no major issues.
2- not long after I bought the the truck I had a steamy underhood leak; which ended up being somebody forgot to slide the clamps back down on the coolant hoses on top of the engine.
3- It's been flushed out to the green coolant.

 

Could I look down the throttle body, or stick a mirror down there and see any of what I need to look for ?

 

Anyone else have any input ???


Still seems to be a "cold" thing. It's not real severe, but I can feel pulsing usually before it gets ready to shift. (mild acceleration)

 

Well that's disappointing. "Everyone here will help till we get it straight"

 

I think some people are pretty busy these last several weeks. When you say pulsing what do you mean?


Seat of the pants feeling? exhaust pulsing? Anything shaking?