Long story short: long battle with this 2000 Blazer, thought I had it reliable and suddenly started bucking at Hwy speeds and stalled. Wait a few minutes and starts back up, drive a few miles and repeat. Fuel system pressure / leakdown at the test port was fine (static and running) (didn't check it at filter).

A little research indicated Cam sensor. Replaced cam sensor and ICM for good measure.

Now the dang fuel pump won't activate ...... what the heck is going on?

 

So went back to it and rechecked .. fuel pump is good and pressure is good.


Reinstalled Cam sensor, rotor, cap, ICM. Does start but feels / sounds like hitting only one cylinder.
No Codes or Check Engine light.

Baffled here ......... Help Please .....

 

Some options:

Fuel pressure while driving (tape gauge to windshield).

Injector leak down/pulse test.

Strength of spark with gap tester or probe tip.

Cylinder drop out test (pull plug wires one at a time).

Fuel trim readings with live scanner.

Does anything change when the fuel system goes closed loop?

What do the o2 sensor graphs look like while running?

George

 

Perhaps I didn't make it clear enough . It was running OK but occasionally stalling. Changed the Cam Sensor and ICM. Now hardly runs at all as though only on one cylinder.