ZR-1 Maintenance Tips

General Maintenance

by Jim VanDorn


The most common call we receive by far is from a confused ZR1 owner. After years of reading everything from which thermostat to use, to what type of spark plug is best, the average owner is totally and completely confused...and for good reason. There are many varied opinions of what is best for our cars but that may depend greatly on how you use your ZR1.


After seven years plus, many ZR1's are finally accruing some mileage. We have had the opportunity to closely inspect many engines with a variety of types of use from normal street driving to severe "weekend" use (track time). Compiling this information we can now offer the ZR1 owner some observations. One rule we've adopted after hearing so many owners say the same thing is the "DIMWIT" or "Darn, if I didn't Mess With IT" rule. In other words, if you didn't have a problem, then what are your intentions in the first place? To date, the only company known to have a fleet of engineering ZR1's to test with was GM and it's affiliates.


Therefore, we must ask ourselves if their suggested procedures and parts recommendations should have a considerable amount of merit. Obviously they do, but on the other hand, there are no doubt areas for improvement. Although we will begin our segment discussing the routine and normal maintenance of the ZR1, there are many areas where an upgrade will be suggested.


Please understand that these are personal opinions and experiences and are not intended to conflict with service procedures outlined in the appropriate service manual.


The fuel gauge on the ZR1 varies significantly from car to car but we have done some testing and made several observations. Most ZR1's will run empty after approximately 18 gallons of fuel are used. We once verified this using three different cars. The vehicles actually ran out of gas within feet of each other and all took between 17.6 and 17.8 gallons when filled to capacity. It is believed that the other two gallons of the 20 gallon tank's alleged capacity either doesn't exist or remains in the valley of the bottom of the tank.

The ZR1 has two fuel pumps located within the fuel tank. The lower pump is the primary and supplies fuel constantly. The secondary pump, located above the primary, is activated by the power key and will run dry when only 3-5 gallons of fuel remain. This starvation will also be felt at just below a half tank indicated when the vehicle is used in aggressive cornering maneuvers.

Note #1: Today's fuel pumps are lubricated and cooled by the fuel itself, therefore, a pump that is allowed to run dry may experience a much shorter service life.

Note #2: '93 ZR1's produced between January 1 and mid-February were equipped with a slightly longer filler hose to reduce the filling capacity by 2 gallons. This was a quick fix to remedy a slightly overweight car which did not adhere to Federal certifications. After mid-February, the heavy front and rear rubber bumper absorbers were replaced with much lighter Styrofoam units. This upgrade continued for the entire production of all C4 Corvettes through '96. By removing the sender, an owner can restore the fuel tank to it's full capacity by simply removing the clamp and added rubber hose extension.

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