I have a performance issue with my engine. There is a point in about
the middle of the throttle range, just about the point where the second
barrel starts to open, where the engine acts as if the mixture is too
lean (hesitation, loss of power, difficulty climbing hills, sometimes
backfiring through the carb). When the engine is cold, it doesnąt
exhibit this problem if I press the accelerator all the way to the
floor. But after the engine warms up, flooring the accelerator doesnąt
cause the engine to go any faster.
It's a 1982 Chevrolet S-10 pickup with the original engine (over
200,000 miles, but with oil pressure still around 30 PSI at warm idle)
and a łnew˛ stock Rochester 2SE carburetor (a VaraJet II without the
electronic feedback components).
- Instead of the stock mechanical fuel pump, it is running a universal
inline electric fuel pump running 6-8 PSI. The fuel pump is brand new.
- Aftermarket true dual exhaust which was added before I bought the
truck. A pipe going from each exhaust manifold to a muffler and
tailpipe. No catalytic converters.
- The charcoal canister for venting and emissions is bypassed.
Maintenance and Troubleshooting:
The fuel pump is brand new
- The carburetor was purchased rebuilt by Champion brand and replaced
less than a year ago.
I replaced the gasket/adapter plate between the carb and intake when
the carburetor was replaced.
I've checked for air leaks, blocking all the vacuum stems at the
carburetor, and checking around the intake with a stethoscope.
I replaced the vacuum distributor advance a couple of years ago. It
is connected, and checking with a timing light reveals that it is
Any ideas where to look next?
Many thanks in advance.
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