83 s10 code 4-4 (running lean)

Hello,since I love this Blazer I would like to fix my problem.
1983 2.8 California model. Rebuilt about 30,000 miles back.

When I start to accelerate from a stop or increase my speed it bogs down like the accelerator pump isn't working.(manually depressing the acc pump will make fuel go into the carb.) When driving at a normal speed it also seems to randomly miss.
No backfiring or spitting back through the carb.
10,000 miles back I replaced the carb (rebuilt unit) Replaced the O2 sensor, fuel filter, pvc valve. cap and rotor, plugs and plug wires, air filter, vacuum lines.
I have rechecked the vacuum lines, checked for loose wiring and/or connectors being loose.
If I someone would provide me with a list of the most likely things to check it would really, really be appreciated.

thanks,iamsnakebit

-connect carburetor fuel feed line to empty bottle, crank engine for 15sec.

-fuel pump should supply 1/2 pint or more in 15 seconds, if below 1/2 pint check for restrictions.

-disconnect fuel line at the carburetor, connect low pressure gauge, start engine. Pressure should be between 4 and 6.5 psi if not check for restrictions in fuel tank sender filter, lines or hoses

-disconnect inlet hose at the fuel pump and connect a vacuum gauge, then crank engine or run engine until maximum vacuum is reached. If your reading is less then 15in Hg replace fuel pump.

thanks 3100, I'll check this out this week.
thanks again, iamsnakebit

I have a 1996 LS with the 4.2 engine. Have same problem and I replaced the fuel pump. No change. Mine seems to be affected at speeds over 55 but not at all if you accelerate.

I have a 1996 LS with the 4.2 engine. Have same problem and I replaced the fuel pump. No change. Mine seems to be affected at speeds over 55 but not at all if you accelerate.


totally different engines and fuel pumps :)

I understand that there is a difference in the engine, I was hoping for some common ground on a similar problem. I guess it's time to start replacing sensors.:frown: