• Got the Contributing Memberships stuff finally worked out and made up a thread as a sort of "How-To" to help people figure out how to participate. So if you need help figuring it out, here's the thread you need to take a look at -> http://www.corvetteflorida.com/forums/showthread.php?t=3581 Thank you, everyone! Rich Z.

C4 Gas Milage

B

budammo

New member
I recently installed new Fuel Injectors, Fuel Pressure Regulator, EGR Valve, Spark Plugs, Wires, Distributor Cap, etc in my 1989 Corvette. After the installation of these new parts, my Gas mileage decreased from 24 highways and 20 city to 18.5 both in the city and highway. I am at a loss of why the gas mileage has decreased. Cannot understand why there is a decrease in the highway mileage. What can be the cause the decrease in highway mileage? Any help would be appreciated. Thanks.
 
Assuming you replaced your injectors with the same flow rate replacements....Check and make sure you didn't leave the vacuum line for the fuel pressure regulator off. Also check your fuel pressure to make sure its OK. If its set with a higher base pressure, it may take the computer a while to 'learn' the new characteristics of the system and adjust the fuel trim. If you're running a higher baseline pressure and don't want to lower it to the stock setting, disconnect your battery for 10-15 minutes and then reconnect.
 
gsdave said:
Assuming you replaced your injectors with the same flow rate replacements....Check and make sure you didn't leave the vacuum line for the fuel pressure regulator off. Also check your fuel pressure to make sure its OK. If its set with a higher base pressure, it may take the computer a while to 'learn' the new characteristics of the system and adjust the fuel trim. If you're running a higher baseline pressure and don't want to lower it to the stock setting, disconnect your battery for 10-15 minutes and then reconnect.
Click to expand...

:iagree:
 
gsdave said:
Assuming you replaced your injectors with the same flow rate replacements....Check and make sure you didn't leave the vacuum line for the fuel pressure regulator off. Also check your fuel pressure to make sure its OK. If its set with a higher base pressure, it may take the computer a while to 'learn' the new characteristics of the system and adjust the fuel trim. If you're running a higher baseline pressure and don't want to lower it to the stock setting, disconnect your battery for 10-15 minutes and then reconnect.
Click to expand...

Thanks for the help. The replacement injectors had the same flow rate has the original injectors. The vacuum line to the fuel pressure regulator was not all the way pushed on, but it was partially on. My vette has the original fuel pump and the fuel pressure checks out OK. Could the fuel pump be going bad? I disconnect the the battery tomorrow and see if the mileage improves. Again, thanks for the assistance and help. I sincerely appreciate your advise.
 
Check that vacuum line on the fuel pressure regulator for cracks as well. I would not expect the fuel pump going bad to cause poor mileage.
 
Thanks gsdave for your help. As you suggested, I disconnected the battery for 15 minutes and then reconnect. After that I took the vette for a 50 mile drive and the highway gas mileage increased to 21 miles per a gallon and was still increasing when I drove in the driveway. I appreciate your assistance.
 
Those chips are pretty hit and miss. Some of them are junk, but even the good ones can only help so much. I'd recommend checking out some of the stuff from TPIS if they still carry TPI parts anymore. They have a good reputation, but are expensive. Unfortunately, there's not a lot of aftermarket support for the older TPI cars anymore.
 
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