If you own
an older car, be advised. The high ethanol-content gas
in use today can cause problems when fed to engines not made
to use it. Not so much burn it ethanol fuel has some
advantages, including octane enhancement.
arise when alcohol-laced fuel comes into contact with and
eats away at rubber and plastic parts, including gaskets,
rubber diaphragms, seals, o-rings and so on. The alcohol in the
fuel also accelerates the rusting out of steel parts such as fuel
lines and (in older cars) steel fuel tanks (most modern cars have
composite plastic tanks).
gas doesnt keep as well which isnt
a problem for regularly used cars but can most definitely become
a problem for occasional-use older/antique cars (and motorcycles)
that might not burn through a tank of fuel for several months.
I got an object
lesson about all this the other day, when I spent some time over
at my friend Graves shop. He has a 63 Buick Special
which he stores on a lift in one of the not-used bays. We
took it down to take it for a ride. The engine would fire, but stall
out when you gave it any pedal. So, we popped the hood and looked.
Peering into the carburetor while pulling the throttle arm revealed
a weak-looking squirt of fuel into the venturis. Faulty/sticking
accelerator pump, we reasoned.
unlike fuel injection, works off negative pressure. The vacuum created
by a running engine draws the fuel from the carburetor into the
intake manifold, and from there to the cylinders. But, theres
a catch. When you stab the gas, the vacuum signal momentarily decreases
which would ordinarily result in a stumble or stall
exactly the problem we were experiencing. The accelerator pump
assuming it is working shoots gas into the engine to ward
off the stumble that would otherwise occur due to temporary fuel
pump was clearly not working. But, why?
old Buick has the 215 aluminum V-8 and Rochester dual-jet (two barrel)
carb, so its an easy job to access/repair the accelerator
Well, it should
We pulled the
carb off the engine and took it apart. It was filled with the debris
of decomposing fuel and rubber. The accelerator pumps
flexible rubber diaphragm was shriveled up and physically dissolving.
The goop inside the carb was likely the admixture of
the remains of the rubber, in solution with the ethanol-laced gas.
I wish I had thought to bring my camera. But what was really startling
is that my friend Graves had put a fresh accelerator pump in this
carburetor just three years previously! The 10 percent ethanol in
virtually all modern gas needed only that long to chew
the thing to ruin. The carbs internal passages were also partially
occluded with crud and goop. Amazing the car even started. We cleaned
the whole bugger out, put in a new (ethanol compatible) accelerator
pump cup, gaskets and bolted everything back together. Car ran perfectly.
But for how
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automotive columnist and author of Automotive
Atrocities and Road Hogs (2011). Visit his
© 2012 Eric Peters
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