Reman 1997 Chevy 5.0 bad gas mileage


Asked by May 20, 2014 at 12:17 PM about the 1997 Chevrolet C/K 1500 Cheyenne Extended Cab SB 4WD

Question type: General

I just had my mechanic install a Jasper remanufactured Engine in my 97 Silverado 2wd. I
just did a direct changeout (same size engine) 5.0 to 5.0. While this was being done I sent
my ECU out to be "tuned". With my old engine I was able to achieve 15 mpg average and
at its worst at the end we were looking at 13mpg. I now have about 5000 miles on the
reman engine and I havent got any better than 11.5 mpg since the changeout. Any ideas?
Could the tune be my culprit?  I also have a K&N intake, 3" catback exhaust, and a 3
chamber flowmaster. All of these I had for 5 years before I changed the engine. I also had
a new cat installed after the engine changeout too. Any help would be awesome! At this
point I can't afford to keep my truck or to get rid of it.

7 Answers


What did you do to the ECU? Tuned as in more performance? If so, you will use more fuel. Also a new engine will get worse gas mileage due to it being new and tighter internal tolerances. Once you get over 5K, you should see some improvement once the engine is broken in.

1 of 1 people found this helpful.

No, I wanted good fuel economy. I put a lot of miles on my truck.


OK, are the tires at the right pressure? Try cleaning the MAF, I see you put a K&N filter in, and if the oil from the filter gets on the MAF element , it could effect the MPG. Go to to see how. If so that checks out, then I'd wait a couple more thousand miles to see if the MPG improves before you get rid of it.

1 of 1 people found this helpful.

Yea everything is good. Having ac problems all of a sudden now. Could my ecu be bad?


check your fuel pressure/leakdown rate. Its a vortec engine with the spider injectors. The fuel pressure regulator is a known problem to fail and start leaking a little. Early sign is poor fuel economy. Just a thought, do you know what year 5.0 you swapped to? I'm wondering the cam it has

1 of 1 people found this helpful.

I have no idea what year they changed it out with. I will ask my mechanic to check the fuel pressure stuff as I do not have a Guage or knowledge to do so. Thank you for your help!


check your ecu the ac system works thru the ecu if your ac is malfunctioning is probably a good sign that theres an internal ecu issue I work on this models all the time goodluck godbless

Your Answer

Add photo

Related Questions

  • Gas Mileage 3 answers

    I have a 1994 Chevy K1500. I seem to only be able to get 10 mpg city. I have a singlestraight pipe, 3" from the headers to a 5" tip. I dont drive very far all the time but the little miles add up. ...

    1994 Chevrolet C/K 1500 Silverado Extended Cab SB 4WD



  • It would be interesting how many miles everyone is pushing. I have a 1992 chevy ext cab 100000 miles. on my chevy... 106 answers

    Chevrolet C/K 1500



  • How to Increase Fuel Mileage on '88 Chevy P/U? 4 answers

    I have an '88 Chevy Single Cab 1500 2WD with a 350. Basically stock. It was short blocked at 100K with a tranny rebuild at 130K, and currently has 180K. I put it in the garage 8 years ago and basic...

    1988 Chevrolet C/K 1500



  • Gas mileage 2 answers

    How far can i get in my 96 silverado 5.7L with a full tank of gas?

    1996 Chevrolet C/K 1500 Silverado Extended Cab LB



  • Gas Mileage 37 answers

    I have a 95 Chevy ext. Cab right now. Is there anything that I could possibly do to increase the gas mileage on my 5.7 liter gas Engine??? Cold Air Intake? New Air Filter? New Spark Plugs or any hoses...

    1995 Chevrolet C/K 1500


    Car Customization

C/K 1500

Looking for a Used C/K 1500 in your area?

CarGurus has 892 nationwide C/K 1500 listings starting at $2,500.


Search Chevrolet C/K 1500 Questions

Chevrolet C/K 1500 Experts

#1 Andrew Olsen
Andrew Olsen
Reputation 3,340
#2 John Saffrahn
John Saffrahn
Reputation 2,500
#3 Rowefast
Reputation 2,050
View All

Related Models For Sale

Used GMC Sierra 1500
822 Great Deals out of 68,199 listings starting at $2,484
Used Ford F-150
2,194 Great Deals out of 206,316 listings starting at $1,499
Used Chevrolet C/K 2500
214 listings starting at $2,250
Used Dodge Ram 1500
453 Great Deals out of 11,151 listings starting at $700
Used Chevrolet Tahoe
550 Great Deals out of 29,235 listings starting at $1,699
Used Chevrolet C/K 3500
237 listings starting at $4,995
Used Chevrolet Camaro
225 Great Deals out of 30,943 listings starting at $1,217
Used Toyota Tacoma
544 Great Deals out of 40,814 listings starting at $2,495
Used Chevrolet S-10
10 Great Deals out of 1,345 listings starting at $1,395

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.