88 4x4 running rough at best

[Dave884x4]

I have an 88 s-10 Blazer 4x4 with the 2.8 Tbi. I was driving to work and it felt like some one turned off the car, it wouldn't even get across the intersection without pulsing the gas, got it to the office and it died, and wont stay started. Trouble codes make no sense, said it was o2 sensor, replaced it against my better judgment, it did not fix anything. I was checking the sensors and I unpluged the vacuum side of the map sensor, it stayed running, of course it threw a low vacumm code, can I get some ideas on whats going on, I had another map sensor, stuck it on there without any change in results, throw me some ideas guys, alot of you are much smarter than me, I have seen your posts.

[MT-2500]

Any codes or check engine lights?
How is the basic tune up end?
When was you last tune up?
Is the secandary ign system and fuel pressure good?
Any missing cylinders?

[Schrade]

Any loping at idle when warm?

[Dave884x4]

Any codes or check engine lights?
How is the basic tune up end?
When was you last tune up?
Is the secandary ign system and fuel pressure good?
Any missing cylinders?

Since I cleared the O2 sensor code, the only code I got was when I was playing with the map sensor, basic tune up is good, plugs were done a few months back, wires also, just past emissions about a month ago. As far as I know the ignition system works fine, don't have a pressure guage for the fuel, but it is sure getting fuel, I loosened the lines and lost about 3 bucks worth on the intake manifold, not the best way to check I know, but I am confadent its not the pressure to the TBI, now, what about the pressure after the regulator, how do I test that. I do have the throttle body from my other blazer, it is off a 4.3, but the regulator is the same , i think. No missing cyl. If I pulse the throttle, I can get it up to about 4k rpm, it seems to run steady, but not for long.

[Dave884x4]

It lopes very bad, like a top fuel dragster with a cold

[Dave884x4]

Problem solved, turns out that the fuel pump started to go out, when I checked the fuel pressure the first time it was at 9 psi, which is within limits, I decided to check it again when it wouldn't start at all, it barley showed up to 2 psi, replaced the pump, problem solved, thanks for the help.

[Schrade]

Originally Posted by Dave884x4

Problem solved, turns out that the fuel pump started to go out, when I checked the fuel pressure the first time it was at 9 psi, which is within limits, I decided to check it again when it wouldn't start at all, it barley showed up to 2 psi, replaced the pump, problem solved, thanks for the help.

9??? I'm surprised it would start with 9psi.

You said it loped like a dragster. That's more like missing fires. When I say loping, I'm meaning, do the rev's go up and down 150 - 250 rpm's all by itself when warm, sitting at idle?

[Dave884x4]

no, it acted as if it was starving for gas, the book says 9-13 psi. the new one only tests at 11 psi. There was plenty of spark, and fuel volume, just not enough pressure. it has been about 60 miles so far, no problems, I guess evey car has its own attitude.

[MT-2500]

Originally Posted by Dave884x4

Problem solved, turns out that the fuel pump started to go out, when I checked the fuel pressure the first time it was at 9 psi, which is within limits, I decided to check it again when it wouldn't start at all, it barley showed up to 2 psi, replaced the pump, problem solved, thanks for the help.

You are welcome.
Yes always test when no start.
Thanks for posting back the fix.
Good Luck