I had to replace the fuel tank on my '97 Lumina 3.1 150k miles as it
developed rust holes 1/4 inch above the pinch weld in the back where the
weld is bent up some to allow for the straps. Apparently this area holds
road grime (and moisture) quite well.
Symptoms were a fuel smell, yellow stain on the tank exterior, plugged fuel
filter, fried fuel pump, high long term fuel trims under load (+19.5%), and
a bad surging misfire when first restarted hot that made my aftermarket tach
swing between 500 and 1500 RPM about 3 times per second. Revving the engine
once usually cleared this up but then it got worse to the point that when
put in gear the RPM fluctuated so rapidly it made the serpentine belt chirp
and a couple times even caused a flashing MIL and a P0300 random misfire
code. Oddly no EVAP leak codes were present. This is per an OTC 4000
Enhanced scan tool and the Pathfinder '96 software.
Post mortem teardown inspection of the pump revealed that it was made in
'03, the commutator was fine, but the copper flex wire from the positive
terminal to the carbon brush was completely gone so the current had to go
through the spring instead which acted as a resistor and slowed the pump
down and the heat both made the spring lose its tension and discolored the
plastic top of the pump around the terminals. I can't believe the pump
assembly costs over $300 new.
For now I have in a salvage yard tank and I cleaned off the surface rust in
the areas that rusted through on the other tank and smeared on some good
grease to hopefully protect the metal. I plan to install a new tank in the
My question is why if a '91 Caprice 9C1 (with approx 300k miles when junked,
VSS went bad along with the cluster) can have a plastic fuel tank why is the
Lumina's (thin) steel?